Cannabinoid hyperemesis syndrome

In brief

A vomiting illness of heavy cannabis use: what it is and how it is defined

Cannabinoid hyperemesis syndrome (CHS) is a pattern of repeated, stereotyped bouts, each closely resembling the last in how it starts, how long it lasts and how it feels, of severe nausea and vomiting, usually with abdominal pain, in people who have used cannabis heavily for a long time, which stops when they stop ^5,12. Hyperemesis simply means excessive vomiting. The word cannabinoid names the family of compounds in the cannabis plant, of which delta-9-tetrahydrocannabinol, usually shortened to THC, is the one that produces the high and the one the syndrome is attributed to ^34,35. Between bouts most people feel well, and that rhythm of illness and recovery is why the syndrome is classed beside cyclic vomiting syndrome, a disorder of recurrent, stereotyped vomiting episodes separated by weeks of ordinary health ^12,36.

It became an official diagnosis in 2016, when the Rome IV committee, the international panel that defines the disorders of gut-brain interaction (conditions in which the gut and its nervous control misbehave without a visible structural cause), divided the nausea and vomiting disorders into three: chronic nausea and vomiting syndrome, cyclic vomiting syndrome and cannabinoid hyperemesis syndrome ¹. The Rome IV definition has three parts: stereotyped episodes of vomiting that resemble cyclic vomiting syndrome in onset, length and frequency; onset after prolonged, excessive cannabis use; and relief of the episodes by sustained cessation of cannabis ¹². Pathologic bathing, meaning prolonged hot baths or showers, is listed only as a supportive feature, and the criteria must have been met for the last three months with symptoms beginning at least six months before the diagnosis ¹². The Rome V revision published in 2026 kept the syndrome as one of the same three nausea and vomiting disorders ².

The third criterion is the strange one, because it makes the cure part of the definition ^12,37. A person can be suspected of having the syndrome at the first visit, but it can be confirmed only afterward, by watching the episodes stop and stay stopped once cannabis does ³⁷. Rome IV did not say how long that watch should last, so in 2019 the committee writing the adult cyclic vomiting guideline proposed firmer numbers: at least three episodes a year, cannabis use for more than a year at more than four times a week on average, and resolution after at least six months without cannabis, or after a span equal to three of the person's usual cycles ¹². A German psychiatrist who has written repeatedly on the condition argued in 2026 that twelve months is the diagnostically reliable interval, and that most cases in the literature were never followed that long and so remain suspected rather than proven ³⁷.

That distinction matters for everything that follows. When the 2019 committee applied the Rome IV criteria to 376 published cases, only 59, or 15.7%, qualified, almost entirely because the authors had not followed their patients after they stopped ¹². Most of what is known therefore describes a syndrome that is suspected in emergency departments and confirmed in a minority ¹². Its typical portrait, pooled from 183 articles in a 2017 systematic review (a study that gathers and grades every report on a question by a stated method), is regular cannabis use in every case, at least weekly use in 97.4%, abdominal pain in 85.1% and relief from hot baths in 92.3% ⁵; a 2025 review put the usual history at daily or near-daily use for more than two years ⁴. Since 1 October 2025 the United States has had a diagnosis code of its own for the condition ¹⁸.

South Australia, 2004, and the history since, including its reversals

The syndrome was first described in 2004 by J. H. Allen and colleagues at Mount Barker Hospital in South Australia ³. They had identified 19 chronic cannabis users with a cyclical vomiting illness; five refused consent and five were excluded because something else could explain their symptoms, leaving nine, whom they counseled to stop and followed with urine drug screens ³. In every case cannabis use had begun before the vomiting; stopping ended the illness in seven; three people who started again after a period of abstinence became ill again, and two of them recovered when they stopped a second time ³. Nine of the ten patients they discussed showed what the authors called an abnormal washing behavior during attacks, the first description of the compulsive hot bathing that became the syndrome's signature ³. Ethan Russo's later account dates the index case to 1996 ³⁴.

The tenth patient was the first reversal. Allen's group set beside their nine a case that had already been published as psychogenic vomiting, vomiting attributed to the mind, and concluded that cannabis had caused it too ³. That case was probably one published in 1996 from the department of psychiatry at Westmead Hospital, New South Wales, by G. M. de Moore, the second author of the 2004 paper: a 22-year-old man whose vomiting was attributed to anxiety, with marijuana use noted, who developed air in the center of the chest and under the skin (pneumomediastinum and subcutaneous emphysema) ⁵⁰. The 2004 abstract does not name the reassigned case, so the identification rests on the matching year, author and diagnosis ^3,50. The habit of looking elsewhere first has not gone away: published cases suggest an average of three to six years between the first episodes and the diagnosis ²².

For several years the reports came one or a few at a time ¹². A 2008 case from Arkansas described a man whose nurses watched him shower compulsively and whose vomiting, pain and showering all stopped after drug rehabilitation ⁵¹. In 2010 a Michigan group described eight patients who averaged 19 years of use before the vomiting began, vomited every three hours during attacks and spent about five hours a day bathing; four of the five who stopped recovered, the three who continued stayed ill, and one relapsed on resuming ²⁶. A 2011 review divided the illness into prodromal, hyperemetic and recovery phases ²⁵, and in 2012 the Mayo Clinic published 98 patients, the largest series then, though follow-up was available for only 10 ⁵².

Codification followed: the Rome IV category in 2016 ¹ and a systematic review in 2017 that graded the evidence and found the mechanism unclear and cessation the best treatment ⁵. Codification did not end the doubt. In 2016, the year of Rome IV, a review whose senior author was Thangam Venkatesan, later first author of the 2019 adult criteria and of the 2026 JAMA review, called it a 'purported condition' that was 'indistinguishable from' cyclic vomiting syndrome, treated by abstinence 'despite scant evidence that marijuana use is causative' ^12,53,54. The next reversal was one of confidence rather than of cause. In 2019 the cyclic vomiting guideline committee showed that only about one published case in six met the criteria, proposed that the syndrome might be a subset of cyclic vomiting syndrome unmasked by cannabis rather than a separate disease, and warned that the label was being applied too quickly and could lead clinicians to withhold care ¹². Since then the field has acquired its first randomized trials, in which chance decides who receives which treatment ^13,55, emergency medicine guidance in the United States and the United Kingdom and a gastroenterology practice update in 2024 ^14,56,57, a pediatric guideline in 2025 ⁵⁸, a dedicated United States diagnosis code in October 2025 ¹⁸, the Rome V revision in 2026 ², an emergency medicine review in 2026 ⁵⁹, and a clinical review in JAMA in August 2026 ⁵⁴.

How an episode unfolds: prodrome, hyperemesis, recovery

Clinicians describe the illness in phases ^25,36. A 2011 review set out three: the prodromal phase, the hyperemetic phase of relentless vomiting, which usually settles within 48 hours with supportive care, and the recovery phase ²⁵. In Russo's description the prodrome is prolonged, with morning nausea, often with anxiety, sweating and flushing; the hyperemetic phase adds abdominal pain and bathing that becomes compulsive; and recovery after stopping cannabis may take a long time to become complete ³⁴. Later reviews add a fourth, interepisodic phase of baseline health, the same four-part rhythm used for cyclic vomiting syndrome ³⁶.

The prodrome is the phase in which the trap is set, because its early-morning nausea is often treated with more cannabis, which seems to help ²³. In an anonymous online survey of 1134 people who identified themselves as having diagnosed or suspected cannabinoid hyperemesis syndrome, recruited in late 2024 from social-media groups devoted to it (a self-selected sample), prodromal symptoms clustered in the morning in 63.1%, nausea and stomach pain were the main complaints, and women reported more frequent and longer symptoms than men ²⁴. The hyperemetic phase is what brings people to hospital: in the Michigan series patients vomited every 3.0 hours on average, bathed or showered five times a day for a total of about five hours, and seven of eight described intense thirst ²⁶; abdominal pain was recorded in 86% of the Mayo Clinic patients ⁵².

Tests mostly exclude other things ^27,28. A six-year audit of 142 presentations by 67 adults at a Melbourne hospital found a raised white blood cell count with neutrophils (the white cells that rise with stress and inflammation) in 75.8%, mild hypokalemia (low blood potassium) in 57.9%, a normal lipase (the pancreatic enzyme that rises in pancreatitis), a C-reactive protein (a general marker of inflammation) that was usually only mildly raised, and largely normal imaging ²⁷. In a pediatric cohort, a group of 125 patients whose hospital records were reviewed, those with the syndrome were older than those with cyclic vomiting syndrome (18.1 against 14.5 years) and had a positive urine drug screen in 86% against 2.9%, slightly lower potassium and higher creatinine (a marker of kidney function); imaging was done in 36% of the cohort and showed abnormalities in only 2.4% of patients ²⁸.

Delay is the rule ^22,34. Published cases suggest an average of three to six years between the first episodes and the diagnosis ²²; in Russo's survey 61% waited more than a year ³⁴; and of 18 patients enrolled in a 2025 emergency department study, 72.2% had had a computed tomography (CT) scan in the previous five years ²⁹. A German case report describes a diagnosis made on the fourth presentation, after a normal abdominal CT and gastroscopy (a camera examination of the esophagus, stomach and duodenum, the first part of the small intestine), with complete resolution six months into abstinence ⁶⁴. In people with type 1 diabetes the syndrome can imitate diabetic gastroparesis, a stomach that empties too slowly, and older age, longer diabetes, female sex and nerve damage point toward gastroparesis instead ⁶⁵. The reverse error happens too, as in an adolescent whose weight loss was blamed on her known hyperemesis until superior mesenteric artery syndrome, a compression of the duodenum by an artery, was found ⁶⁶.

How common it is, and the rise that followed legalization

The first numbers came from Colorado ⁶¹. After medical marijuana was liberalized there in 2009, cyclic vomiting presentations at a Denver emergency department rose from 41 per 113,262 visits to 87 per 125,095, a prevalence ratio (the ratio of the two rates) of 1.92, and patients were more likely to have cannabis use recorded; the authors could not say whether use or reporting had changed ⁶¹. At a Colorado academic hospital between 2012 and 2016, emergency visits attributable to inhaled cannabis were more often for the syndrome than visits attributable to edibles, 18.0% against 8.4% ⁶⁷. In France it first appeared in 2015 in national addictovigilance reports, the official monitoring of drug-related harm, and accounted for 87, or 2.8%, of the cannabis adverse events recorded between 2012 and 2017 ⁶⁸.

Canada, which legalized recreational cannabis in October 2018, produced the sharpest test ⁶. In Ontario, Daniel Myran and colleagues counted 12,866 emergency visits by 8140 people from January 2014 to June 2021; the monthly rate rose 13-fold, from 0.26 to 3.43 visits per 100,000 people, but legalization itself was not associated with a change, while commercialization, the expansion of stores and products that coincided with the COVID-19 pandemic from March 2020, was associated with an immediate rise (incidence rate ratio, the ratio of rates after and before, 1.49) ⁶. In Alberta, emergency visits for vomiting with a cannabis code rose from 15 to 21 to 32 per 100,000 across the year before legalization, the year after and the first pandemic year ⁶⁹. Nationally, Health Canada counted 7533 hospitalizations between 2016-17 and 2024-25, a rise from 1.5 to 3.8 per 100,000 that happened mostly before 2020-21 and then leveled off ¹¹.

The United States data tell the same story at larger scale ^7,18. In a national emergency sample of 188.6 million visits, a proxy for the syndrome (a cannabis code together with a cyclic vomiting code) rose from 4.4 per 100,000 visits in 2016 to a peak of 33.1 in the second quarter of 2020 and stood at 22.3 in 2022 ⁷. In Massachusetts it rose from 0.729 to 10.6 per 10,000 emergency visits between 2012 and 2021 ⁷⁰; among people aged 15 to 24, suspected visits rose by an average of 28.1% a year from 2006 to 2020 ⁷¹; among adolescents aged 13 to 21 in children's hospitals it rose from 160.4 to 1968.3 per million emergency visits between 2016 and 2023, in states with and without recreational legalization ⁸; and in electronic records covering 248 million emergency encounters from 2016 to 2024 it accounted for 134,059 visits, at a mean age of 32 ⁷². In emergency departments reporting to the National Syndromic Surveillance Program of the Centers for Disease Control and Prevention (CDC), a near-real-time monitoring system of emergency records, the share of visits involving the syndrome stayed mostly steady from January 2023 to September 2025 ¹⁸. With the national peak in 2020 ⁷ and the Canadian leveling after 2020-21 ¹¹, the national all-age data describe a steep rise to about 2020 followed by a plateau, not a continuing climb ^7,11,18. When the first specific diagnosis code took effect on 1 October 2025, that share jumped from 3.35 to 11.26 per 10,000 in a month and stayed at 3.7 times its earlier average, which the CDC authors said might partly reflect better recognition and coding rather than more disease ¹⁸.

How common it is among people who use cannabis depends heavily on how it is defined ¹². A 2018 survey at a New York public hospital found that 32.9% of patients who smoked on at least 20 days a month met a definition based on relief from hot showers, which would mean about 2.75 million Americans ⁷³; the 2019 guideline committee judged that an overestimate, because the definition did not even require the vomiting to come in episodes ¹². In a 2023 survey of 10,255 United States cannabis users, about 6% reported past-year symptoms, more often among users of edibles and concentrates and among those who used cannabis to treat nausea or headache ¹⁰. In a nationally representative survey of 7034 adults in 2025, 2.7% of all respondents and 17.8% of daily users reported symptoms consistent with it ⁹, and in the preprint version only 11.5% of those with such symptoms said a clinician had ever diagnosed it ⁷⁴. In an online support-group survey of 1052 people with self-reported cannabinoid hyperemesis syndrome, heavy daily use and starting in adolescence were associated with more frequent episodes ⁷⁵. The surveys disagree on age at first use: starting in adolescence went with more frequent episodes in the support-group survey ⁷⁵, but in the 2023 national sample an older age at first use was associated with higher risk ¹⁰; neither followed people forward from their first use. The Colorado figures, in turn, count what share of each route's emergency visits were for the syndrome, not each route's risk among its users, which may explain why they seem to conflict with the survey's higher risk among users of edibles ^10,67. These are symptom reports, not confirmed diagnoses, but they agree that the syndrome is a frequent experience among daily users and an uncommon one in the population as a whole ^9,10.

The age pattern is consistent: this is a disease of young adults ¹². The Ontario patients averaged 27.4 years ⁶; national United States risk was highest at ages 18 to 25 (relative risk ratio 3.59) ⁷; and Canadian hospitalization rates were highest at ages 20 to 24, though they rose fastest at 45 to 64 ¹¹. The sex pattern is not consistent, and that is a reversal. The case literature was about seven-tenths male, 72.9% in the 2017 review ⁵, and was read as describing a male disease; but 51.5% of the Ontario patients were female and the rise during commercialization was larger in women ⁶, 63.2% of the adolescents were female ⁸, and both the 2025 national survey and the 2026 surveillance report found women more affected ^9,18. Other large United States datasets still found men at higher risk, though in the national emergency sample the difference was small (relative risk ratio for women 0.92) ^7,10,70,71. The 2019 committee had already attributed the male excess of the case series to men's heavier use rather than to biology ¹².

The paradox: a drug licensed to stop vomiting

The syndrome is strange because THC is an antiemetic, a drug that prevents vomiting ²⁰. In a randomized, double-blind crossover trial published in 1975, in which each patient received THC and a placebo in turn, in random order, with neither patients nor doctors knowing which was which, oral THC produced an antiemetic effect in 14 of 20 courses of cancer chemotherapy and placebo in none of 22 ⁶⁰. A 2001 systematic review of 30 randomized comparisons in 1366 patients found the oral cannabinoids nabilone and dronabinol, and injected levonantradol, more effective than the older antiemetics of the day for complete control of nausea (relative risk 1.38, meaning complete control was 1.38 times as common with cannabinoids, about one extra person helped for every six treated) and of vomiting, at the price of dizziness, dysphoria (an uneasy, unhappy mood) and paranoia ¹⁹. Dronabinol and nabilone capsules were first approved in the 1980s and remain approved in the United States for chemotherapy nausea that conventional drugs do not control, and an oral dronabinol solution was added in July 2016 ²⁰. A 2020 randomized crossover trial of a THC and cannabidiol capsule added to modern antiemetics raised the share of patients with a complete response, the trial's main measure of control over the five days after chemotherapy, from 14% to 25% ⁷⁶.

Yet the labeling of the 2016 dronabinol solution already warned that patients may develop new or worsening nausea, vomiting and abdominal pain, which require the dose to be reduced or the drug stopped ²⁰. In animals the picture is the same double one: stimulating the CB1 receptor, the main cannabinoid receptor in the brain, suppresses vomiting in species that can vomit, blocking it reverses the effect, and drugs that push the receptor below its resting activity, called inverse agonists, provoke nausea and vomiting ³⁹. Most of that work is necessarily in ferrets, shrews and rats that 'gape' when nauseated, because rats and mice cannot vomit ^12,39.

The usual reconciliation is dose and duration ¹². Reviews describe a biphasic effect, antiemetic at low or occasional doses and proemetic, provoking vomiting, at high or sustained ones ^46,77, and the 2019 committee framed it explicitly as a hypothesis ¹². It is an inference from pharmacology and case series, not a dose-response curve measured in people ¹². What has been measured is that potency has risen: THC in cannabis seized in the United States climbed from about 4% in 1995 to about 12% in 2014, and the ratio of THC to cannabidiol from 14 to about 80 ⁷⁸; cannabidiol is a non-intoxicating cannabinoid that itself suppresses nausea and vomiting in animals within a limited dose range ³⁹. A later analysis by the same laboratory of 14,234 seized herbal samples found mean THC rising from 9.75% in 2009 to 14.88% in 2018 and 13.88% in 2019, while the ratio of THC to cannabidiol peaked at 103.48 in 2017 and then fell to 24.58 in 2019 as higher-cannabidiol strains appeared, a reversal of the earlier trend ⁷⁹. Seized illicit flower says nothing about the licensed concentrates and vape cartridges now widely sold ⁷⁹. In the 2024 online survey, vape cartridges, a concentrated form, were associated with a shorter time from first use to symptoms ²⁴. Rising potency fits the rise in cases; it has not been shown to cause it ^4,78.

The paradox also explains why the diagnosis is resisted ⁴. Between 40% and 80% of people with cyclic vomiting syndrome use cannabis, by one review's estimate, and many say it eases their nausea and stress ⁴; most users in a specialist clinic said it helped ⁸⁰. In 24 interviews, people with the syndrome contested the diagnosis on exactly that ground, that cannabis treats nausea, alongside the belief that claims of harm were part of a conspiracy ²¹.

Why it happens: the hypotheses, at their strength of evidence

No mechanism is established, and each hypothesis below should be read with its evidence class attached ^5,48. The oldest is tolerance turned upside down. Positron emission tomography, a scan that can image receptors in the living brain, showed in 2012 that chronic daily cannabis smokers have fewer CB1 receptors in the cortex, in proportion to their years of smoking, and that the receptors return to normal after about four weeks of monitored abstinence ³⁸. That downregulation is real and human ³⁸. The step from it to vomiting has not been measured: the 2019 committee speculated that different degrees of CB1 downregulation in genetically predisposed people could flip cannabis from antiemetic to proemetic, and pointed out that THC stored in body fat takes two to three months to clear and that receptor recovery may take longer still ¹². The four-week recovery that the imaging study observed is much faster than the six to twelve months clinicians wait to confirm remission, a mismatch the downregulation hypothesis does not yet account for ^12,38.

A second idea, that attacks come when THC or its breakdown products build up to toxic levels, has been tested and has not held up, a reversal of what many clinicians assume ^47,48. In a Canadian case-control study (one that compares people with a condition against similar people without it), scalp-hair THC was similar in 16 patients, 16 recreational users without vomiting and 14 unrelated emergency patients, and only the ratio of THC to cannabinol, a minor cannabinoid, differed, which led the authors to conclude that heavy use is necessary but not sufficient ⁴⁷. In a 2026 study of 35 patients in an attack and 15 with acute intoxication, mass spectrometry, a laboratory method that identifies molecules by their mass, found no difference in serum THC, its breakdown products, cannabidiol, and two minor plant cannabinoids, cannabigerol and cannabinol, or their ratios ⁴⁸. In ten adolescents, 11-hydroxy-THC, the active compound the liver makes from THC, was actually lower during symptoms (median 0.6 ng/mL) than at a well visit (4.2 ng/mL) ⁴⁹. Whatever triggers an attack, it is not simply a higher blood level ^48,49.

A third hypothesis involves the hypothalamic-pituitary-adrenal axis, the hormonal stress system that runs from the brain to the adrenal glands and releases cortisol ⁴⁴. In 22 people with cyclic vomiting syndrome, salivary cortisol and alpha amylase, a marker of activity in the sympathetic nervous system, the body's fight-or-flight wiring, were higher during attacks in those who used marijuana than in those who did not, from which the authors suggested that chronic use enhances the stress response ⁴⁴. Russo's 2024 review describes the syndrome as frequently accompanied by activation of this axis, with stress and weight loss ⁴⁵, and a 2025 review argues that prolonged cannabis use dysregulates both the endocannabinoid system (the body's own cannabinoid messengers, such as anandamide, with their receptors and the enzymes that make and break them down) and the stress systems ⁴⁶. The human data behind this are a subgroup of one small cyclic vomiting study; the rest is animal work and reasoning ^44,46.

A fourth involves TRPV1 (transient receptor potential vanilloid 1), a channel on sensory nerves described in the next section; its main support is that heat and capsaicin, both of which open it, seem to relieve attacks ^40,43. A fifth is genetic. In 2022 Russo's group genotyped people recruited online through cannabis networks: of 99 patients who agreed, 28 returned kits, against 12 controls ³⁴. They reported variants in COMT, a gene for an enzyme that breaks down dopamine (in 57.1% of patients against 10% of controls; odds ratio, a measure of how much more common the variant was in patients, 12), ABCA1, a cholesterol-transport gene (8.4), TRPV1 (5.8), DRD2, the dopamine D2 receptor gene (6.2), and CYP2C9, the main liver enzyme that breaks down THC (7.8) ³⁴. CNR1, the CB1 receptor gene the authors had predicted, was not significant; no correction for testing many variants at once was stated; the confidence intervals (the range within which the true value probably lies) ran as wide as 1.3 to 88.1 (98.1 in the paper's own table); and two of the five authors listed a commercial genomics company while the paper proposed the variants as a future diagnostic test ³⁴. That makes it a hypothesis-generating candidate-gene association in 40 people, unreplicated as of October 2026; a 2024 review by the same authors restated it without new data ⁴⁵. A separate study of cyclic vomiting syndrome, which did not examine this syndrome, found a CNR1 variant associated with it ⁸¹.

Three further observations sit beside these. THC slows the emptying of the stomach in rodents and in healthy volunteers, which may contribute to the vomiting ¹². Plasma endocannabinoid levels are altered in cyclic vomiting syndrome itself, with higher 2-arachidonoylglycerol, one of the body's own cannabinoids, in ten patients than in eight controls ⁸². And clinicians who follow patients for years describe sensitization: each cluster of attacks after a relapse comes stronger and longer than the last, even at low doses, which has produced a hypersensitization hypothesis that so far rests on case observation ^37,83.

The hot-shower sign, and why heat might help

The hot shower is the detail patients and clinicians remember. Nine of the ten patients Allen discussed washed abnormally during attacks ³; 52 of 57 Mayo Clinic patients asked about it, 91%, reported relief from hot showers or baths ⁵²; the 2017 systematic review counted it in 92.3% ⁵; and in the Michigan series patients bathed five times a day for about five hours in total ²⁶. In Russo's survey, which admitted only patients whose symptoms eased with hot showers or baths, all reported that heat helped and heat was the remedy cited as most effective ³⁴, and in an analysis of 2683 Reddit posts hot water was the remedy mentioned most often ⁸⁴. An early review called it a learned behavior, because the relief is real and temporary ²⁵.

It was once called pathognomonic, meaning diagnostic on its own, and that has been reversed ¹². In a specialist clinic study of 111 people with cyclic vomiting syndrome, 73% bathed in hot water during attacks and more than 80% of them found that it markedly relieved nausea, vomiting, pain and panic; regular cannabis users chose very hot water more often (50% against 16%) and took longer to feel better ⁸⁵. The 2019 committee noted that about half of cyclic vomiting patients who do not use cannabis describe the behavior, 48% against 72% of those who do in one comparison ¹², and a 2025 review repeated that about half do ⁴. The sign points toward a cyclic vomiting illness; it does not tell the two apart ^4,12.

The leading explanation is TRPV1, the transient receptor potential vanilloid 1 channel, a pore in the membrane of sensory nerves that opens in response to heat above about 43 degrees Celsius, to acid and to capsaicin, the hot compound in chili peppers ⁴⁰. The body's own cannabinoid anandamide also opens it, which was shown in 1999 in isolated arteries and in cells carrying the cloned receptor, an early link between the endocannabinoid system and this channel ⁴¹. The hypothesis is that heat on the skin, like capsaicin, activates and then desensitizes TRPV1 and alters signaling by substance P, a messenger of nausea, in the brainstem's vomiting circuitry, the area postrema and the nucleus tractus solitarius ^42,43. Others suggest that heat resets a disordered thermoregulation, the brain's temperature control, in which the endocannabinoid system takes part, or shifts blood from the gut to the skin ^77,85. Some authors have proposed that chronic cannabinoid use downregulates TRPV1 itself ⁸⁶.

The evidence class is low. No study has measured TRPV1 in people with the syndrome; the support is pharmacological reasoning, the apparent response to capsaicin and an unreplicated genetic association ^34,40. The bathing also has a cost. The combination of relentless vomiting and constant hot showers can dehydrate a person enough to cause acute kidney failure; the authors of one such case in 2014 found five others among 55 published case reports ³⁰, and in 2026 a Colorado group that included a county coroner's office reported two men with long-standing disease found dead in bathtub or shower settings ¹⁷.

Treating the episode: every trial, at its size

In practice, emergency departments reach first for ondansetron, a blocker of the serotonin 5-HT3 receptor that is the standard antiemetic for most vomiting; in records of 134,059 United States visits it was given in 58.7%, with haloperidol second at 32.6% ⁷². Supportive care means intravenous fluids and replacement of potassium, and the 2017 review found some benefit from fluids, dopamine antagonists (drugs that block dopamine receptors) and capsaicin and advised avoiding narcotic painkillers ⁵; a 2025 pharmacy review holds that opioids and benzodiazepines should not be first-line ⁸⁷. No randomized trial found for this page has tested intravenous fluids or potassium replacement for the syndrome; they are given because vomiting and hours of hot bathing dehydrate and deplete potassium, and their support is case series, observational reviews and expert consensus ^5,27,30. Hot water itself is offered as an abortive measure, one meant to cut an attack short, at home and in hospital ⁸⁸.

Haloperidol, an older antipsychotic that blocks the dopamine D2 receptor, entered with a single 2013 case report ⁸⁹. It is the only drug tested against another active drug in a completed randomized trial for the acute attack ^13,90. In HaVOC (named for Haloperidol Versus Ondansetron for Cannabis hyperemesis syndrome), a triple-blind trial, meaning that neither the patients, the clinicians treating them nor those measuring the results knew which drug had been given, at Queen's University in Kingston, Ontario, 33 cannabis users with active vomiting were enrolled and 30 were treated, 13 with intravenous haloperidol (0.05 or 0.1 mg per kilogram) and 17 with ondansetron 8 mg ¹³. Haloperidol reduced pain and nausea by 2.3 cm more on 10-cm visual analog scales (lines on which the patient marks severity) at two hours (95% confidence interval 0.6 to 4.0), and its patients left the emergency department earlier (3.1 against 5.6 hours; 95% confidence interval for the difference 0.1 to 5.0 hours) ¹³. Fewer haloperidol patients needed rescue antiemetics, extra drugs given when the first does not work (31% against 59%), but that difference was not statistically certain (95% confidence interval -61% to 13%) ¹³. Two patients returned with acute dystonia, a painful involuntary muscle spasm, both from the higher dose ¹³. Thirty patients is a small trial, but it reversed the default: ondansetron, the drug most patients still receive, did worse ^13,72. Haloperidol also prolongs the QTc interval, the heart's electrical recovery time on an electrocardiogram corrected for heart rate, and in two adolescents given haloperidol, one with low potassium and magnesium, the QTc reached 528 and 476 milliseconds ⁹¹.

Droperidol, a close relative, has only observational evidence, from studies that look back at how patients given it in ordinary care fared rather than assigning treatment by chance ⁹⁰. In Melbourne, the 37 of 76 presentations treated with droperidol, usually 0.625 mg, had a median stay of 6.7 hours against 13.9 hours ⁹²; in Atlanta in 2024, droperidol in 77 of 211 encounters was associated with a stay of 409 against 641 minutes and less opioid use, with two mild adverse reactions ⁹³; and a single-arm study of 47 patients given droperidol with diphenhydramine, an antihistamine that is also sedating, found nausea scores falling from 8.3 to 1.4 over two hours, with 12.9% returning within a week, but had no comparison group ⁹⁴.

Capsaicin cream, rubbed on the abdomen to mimic the hot shower, has the most studies and the weakest single result ⁹⁰. After earlier single case reports, among them a 2016 Spanish case letter ^5,40,95, a 2017 case series described 13 patients at two academic centers, all reported to improve after other treatments had failed ⁴². A Colorado cohort of 43 found no significant difference in length of stay but fewer additional doses and less opioid ⁹⁶; a Michigan cohort of 201 found that 55% against 21% needed no more than one rescue drug and left sooner after it, without a shorter total stay ⁹⁷. The one randomized trial, a 2020 pilot in Detroit of 30 patients, found nausea at 30 minutes, its primary outcome (the one result the trial was designed to test), not significantly better than placebo (4.1 against 6.1 cm), nausea at 60 minutes 3.2 against 6.4 cm, and complete resolution in 29.4% against none; one patient stopped because of skin irritation ⁵⁵. A 2021 meta-analysis, a statistical pooling of studies, combined 7 studies and 106 patients ⁹⁸, and the 2024 guideline evidence review called the capsaicin data mixed across five studies and 386 patients ⁹⁰. A search of PubMed for this page found no larger randomized trial of capsaicin for the syndrome through October 2026; newer reports are single cases ^86,99 and a pediatric before-and-after study in which a treatment algorithm raised capsaicin use from 2.7% to 22.2% without changing admissions or length of stay ¹⁰⁰.

Benzodiazepines, sedatives such as lorazepam, were the drugs most often reported effective for the acute attack in a 2017 systematic review of 205 patients, followed by haloperidol and capsaicin, though most of its 63 articles were case series or case reports and high-quality evidence was limited ¹⁰¹; a 2025 review of 63 individual cases likewise found capsaicin, antipsychotics and benzodiazepines reported to work better than the usual antiemetics ¹⁰², as did a pediatric chart review ¹⁰³, and in a series of six adolescents, four given haloperidol with lorazepam and one given haloperidol with capsaicin had full acute relief ¹⁰⁴. Aprepitant and fosaprepitant, which block the neurokinin-1 receptor for substance P, have at least four published successes, three of them after other drugs failed ^91,105,106. A nerve block beside the thoracic spine ¹⁰⁷ and sniffed isopropyl alcohol ¹⁰⁸ have one case each.

Guidelines reflect that thinness honestly. The Society for Academic Emergency Medicine's 2024 guideline suggests haloperidol or droperidol, and offering capsaicin, in addition to usual care, each at very low certainty of evidence, the lowest grade in the GRADE rating system, meaning the panel has little confidence that the true effect is close to the estimate ¹⁴; the Royal College of Emergency Medicine's guidance includes haloperidol and capsaicin among its recommended options ⁵⁶; and the American Gastroenterological Association issued an expert clinical practice update the same year ⁵⁷. A 2025 review adds that patients deserve nonjudgmental care and an agreed emergency care plan ⁸⁸, and the 2019 committee warned that people with possible cannabinoid hyperemesis syndrome should not be denied the treatments that help cyclic vomiting syndrome ¹².

Stopping: the only cure, and the relapse data

Every source agrees on one treatment that ends the illness rather than the attack: stopping cannabis ^5,35. In Allen's series cessation ended the vomiting in seven of nine ³; in Michigan four of five who stopped recovered while all three who continued stayed ill ²⁶; at the Mayo Clinic six of the seven followed patients who stopped had complete resolution ⁵²; and the 2017 systematic review counted resolution after stopping in 96.8% of reported cases ⁵. A 2025 pediatric review puts it flatly: since 2004 the only known treatment has been complete cessation of all THC-containing products ³⁵.

Two cautions apply to those numbers. They come from small series in which follow-up was the exception, so they describe the people who were followed ¹². And because cyclic vomiting illnesses can remit on their own (half of children with cyclic vomiting syndrome are well and off medication after four years of illness), a spell without episodes after stopping is not, by itself, proof that cannabis was the cause ¹². That is why the proposed criteria ask for six months or three cycles, why Bonnet asks for twelve months, and why he defines cure as full remission for at least five years ^12,37,83. One German patient's symptoms resolved completely six months into abstinence ⁶⁴. The opposite error is possible too. Withdrawal, which begins within about a week of stopping, can bring vomiting of its own: in a 2025 case, intractable vomiting with frequent hot bathing began five days after the last use and was treated as withdrawal ¹⁰⁹, and in a 2026 pregnancy, vomiting in a woman who had recently cut down her use, attributed partly to suspected withdrawal, settled within a day on gabapentin, a seizure and nerve-pain drug used here outside its licensed indications ¹¹⁰. Vomiting soon after stopping does not by itself show that stopping failed; these are single cases ^109,110.

Relapse is common and well documented ³⁴. In Allen's series three people who resumed became ill again ³. In Russo's survey 79.4% of patients had resumed cannabis and had their symptoms return, often after increasing their intake ³⁴. In the Melbourne audit 29 people re-presented, most within three months ²⁷; 16.7% of 18 emergency patients in Washington, D.C., returned within 30 days ²⁹; and 12.9% returned within a week in a single-arm study of 47 patients given droperidol ⁹⁴. Bonnet's case reports describe each relapse after abstinence as worse than the one before ³⁷.

The reasons are not mysterious. In an internet survey of 157 people in Canada and the United States who reported having the syndrome, a self-selected sample, problematic cannabis use on a standard screening test was universal, 59% screened positive for moderate or worse anxiety and 68% for depression ⁶⁹. All ten adolescents in a Rhode Island pilot study had cannabis use disorder or hazardous use and described withdrawal when they tried to stop ⁴⁹. In the 2025 national survey, people with symptoms reported more use of other drugs, more overdoses, and more depression, anxiety, sleep problems and chronic pain than daily users without symptoms ¹¹¹, and a 2026 preprint from the same survey, not yet peer reviewed, found the highest rates of suicidal thoughts and behaviors in that group ¹¹². In 24 interviews, people who doubted the diagnosis tried changing route, product or amount rather than stopping ²¹, and of 97 YouTube videos about the syndrome only 25.8% were judged useful while 19.6% were misleading ¹¹³.

Treatment therefore extends beyond the emergency department to cannabis use disorder, anxiety and depression ³⁵. Tricyclic antidepressants, the usual preventive drugs for cyclic vomiting syndrome, were the long-term treatment most often reported to help in the 2017 review ¹⁰¹, and the 2019 committee recommended offering cannabis users with moderate to severe cyclic vomiting the same preventive therapy as anyone else, with counseling toward stopping from a team that avoids a confrontational approach ¹².

One illness or two? The argument with cyclic vomiting syndrome

The sharpest disagreement in the field is whether this is a separate disease at all ^12,114. The case for one spectrum was made most fully by the 2019 cyclic vomiting committee: the two conditions look the same in an attack, both affect young people, hot bathing occurs in both, and the case literature for a distinct syndrome rested on follow-up that was mostly missing; the committee concluded that cannabinoid hyperemesis syndrome is probably a subset of cyclic vomiting syndrome in which chronic cannabis use triggers attacks in people genetically predisposed to them ¹². Its members' own clinic data supported that view: of 140 cyclic vomiting patients, 41% used cannabis and 21% used it regularly, and of 57 users, 50 reported stopping for more than a month but only one had episodes stop, and that patient later resumed cannabis and remained free of symptoms; the abstinence was self-reported, and a one-month threshold is far shorter than the six months the committee proposed ^12,80.

The case for two diseases is made by clinicians who see complete recovery ⁸³. Bonnet's 2024 letter to Gastroenterology states it in its title: the syndrome recovers completely when cannabis or synthetic cannabinoids (laboratory-made drugs, sold as 'spice' or 'K2', that act on the CB1 receptor THC acts on) are permanently stopped, and cyclic vomiting syndrome does not ^34,114. Russo and Whiteley call the two clearly distinct in presentation and pathophysiology ⁴⁵, and a 2025 review argues that their mechanisms, epidemiology and management differ, cyclic vomiting being tied to migraine and to the autonomic nervous system, which runs the involuntary functions of heart rate, sweating and digestion ³⁶. In a pediatric cohort the two groups differed in age, drug screens, potassium, creatinine and blood pressure but not in sex ²⁸. In the first detailed series from Mexico, from five centers, the 16 patients meeting Rome IV criteria for this syndrome were older than the 30 with cyclic vomiting syndrome (median 27 against 23 years), used tobacco and risky amounts of alcohol more often, and were diagnosed sooner (26.5 against 35.4 months), and 13.3% of the cyclic vomiting patients also used cannabis; it is a small cross-sectional study, a single snapshot without follow-up ¹¹⁵. The 2025 pediatric guideline treats the syndrome as a related but separate entity ⁵⁸, and Rome V kept the two as separate categories ².

Some data fit both readings. In the national United States emergency sample, cannabis-associated cyclic vomiting rose while cyclic vomiting without cannabis fell from 300 to 186 per 100,000 visits between 2016 and 2022 ⁷, which could mean a new disease, a shift in labeling, or both. Among 35,055 cyclic vomiting admissions, cannabis users had shorter stays and fewer readmissions, which the authors suggested might reflect hidden cases of this syndrome improving after stopping ⁶³. A 2026 study led by the same first author pointed the other way. In a multi-hospital records network, 18,588 people with cyclic vomiting syndrome who used cannabis were matched by propensity score (a statistical method that pairs people who are alike in age, other illnesses and treatment) with 18,588 who did not; the users had more emergency visits (hazard ratio, the ratio of event rates over time, 1.35; 95% confidence interval 1.31 to 1.39) and more hospitalizations (1.11; 1.06 to 1.16), and were less likely to receive preventive therapy ⁶². Both studies are associations in administrative records ^62,63. And the 2019 committee raised the possibility of ascertainment bias, that the first reports simply made doctors ask about cannabis more often ¹². The reverse error is documented too: two adolescents who used cannabis had vomiting timed to the menstrual cycle, and it stopped on hormonal contraception even though they kept using cannabis, so a cannabis user's cyclic vomiting can have another cause; this is two case reports ¹¹⁶.

Where the argument stands in October 2026 is that both camps agree on what to do and disagree on what it is. Both advise stopping cannabis and judging the diagnosis by what happens over months ^12,83. What would settle it is a prospective cohort of heavy users with cyclic vomiting, with verified abstinence and follow-up long enough to count cycles, which the committee called for in 2019 and which no study found for this page has yet provided ^12,80.

Where it leads: kidneys, salts, the chest and heart, the brain, pregnancy and death

Most episodes end, but the vomiting can do damage ^25,30. Dehydration from vomiting and hours in hot water can cause prerenal acute kidney injury, kidney failure from too little blood flow, described in a man with a creatinine of 3.21 whose authors found five similar cases among 55 published reports by 2014 ³⁰; children with the syndrome had higher creatinine than children with cyclic vomiting syndrome ²⁸. Potassium is lost with the vomit, and mild hypokalemia was found in 57.9% of Melbourne presentations ²⁷; case reports describe severe hypokalemia with signs of low calcium and a prolonged QTc ¹¹⁷, life-threatening hyponatremia (low blood sodium) needing intensive care ³¹, and a blood lactate, a marker of tissue stress, of 6.1 mmol/L ¹¹⁸.

Forceful retching can drive air into the chest ³². Pneumomediastinum, air around the heart and great vessels, was described in 2026 as having been reported with this syndrome in only five cases ³², though the 1996 'psychogenic vomiting' case described in the history section had it too ⁵⁰; others have reported it with lung lacerations and a small pneumothorax (collapsed lung) but no chest pain ¹¹⁹, or with pneumothorax in a daily user ¹⁰⁸. Synthetic cannabinoids have produced the same vomiting with rhabdomyolysis, a breakdown of muscle that can block the kidneys ¹²⁰. Retching can also tear the lining where the esophagus meets the stomach (Mallory-Weiss tears), described in a pregnant woman with repeated admissions ¹²¹. In a 21-year-old woman, air tracked around the heart, through the mediastinum (the central compartment of the chest) and behind the abdominal cavity, and raised the alarm of esophageal rupture until imaging excluded it ¹²². In a 63-year-old woman with repeated past admissions for the syndrome who arrived vomiting after cannabis use, a potassium of 2.6 mmol/L accompanied takotsubo cardiomyopathy, a sudden stress-induced weakening of the heart muscle, with a fast abnormal heart rhythm that needed an electric shock and cardiogenic shock (circulatory failure from a failing heart); she recovered over four weeks ¹²³. These are single cases ^121,122,123.

Prolonged vomiting can starve the brain of thiamine, vitamin B1 ^33,124. Two 2026 case reports describe Wernicke encephalopathy, the confusion, unsteady gait and abnormal eye movements of thiamine deficiency: in a 15-year-old who had lost 25 to 30 pounds and whose brain magnetic resonance imaging (MRI) was normal, and who improved within a day of thiamine ³³, and in a woman in her twenties after eight weeks of vomiting and more than 10 kg of weight loss, whose MRI showed changes in the thalamus, a relay center deep in the brain ¹²⁴. Weight loss can also hide another disease, as in the adolescent whose superior mesenteric artery syndrome was missed ⁶⁶.

In pregnancy the syndrome is easily mistaken for hyperemesis gravidarum, the severe vomiting of pregnancy; a 2024 review found only 11 earlier published cases, which its authors thought reflected under-reporting ¹²⁵. In Ontario between 2015 and 2021, pregnancies with acute care for cannabis use had far more acute care for hyperemesis gravidarum than other pregnancies (30.9% against 2.5%), as well as more preterm births and neonatal intensive care admissions, associations that do not separate the syndrome from cannabis use in general ¹²⁶.

Deaths have been reported ^15,16,17. In 2019 Canadian medical examiners described three people with a history of the syndrome, aged 27, 27 and 31, who died after emergency visits for vomiting, with THC in postmortem blood; the syndrome was judged the cause of death in two ¹⁵. In 2021 a 22-year-old with three and a half years of cyclic vomiting and cannabis use since age 14 developed torsades de pointes, a chaotic heart rhythm, during emergency treatment and died; the death was attributed to vomiting-induced hypokalemia together with QT-prolonging drugs, haloperidol and ondansetron among them, with cardiac gene variants contributing ¹⁶. In 2026 two men with long-standing disease were found dead in bathtub and shower settings ¹⁷. These are case reports, and no study found for this page has measured a death rate. The scale of illness is clearer: in United States records about 13.5% of visits ended in admission, with a mean stay of 3.8 days ⁷², and among adolescents 41.1% were admitted to a ward or observation unit and 0.6% to intensive care ⁸.

What was believed and is not, and what is still unknown

That it is rare. For years clinicians called the syndrome rare or very rare with no data behind the word, as the authors of an early prevalence survey pointed out ⁷³. It is uncommon in the population as a whole, but 17.8% of daily users in a 2025 national survey reported symptoms consistent with it ⁹, and emergency departments reporting to CDC's National Syndromic Surveillance Program recorded 199,565 visits involving it between January 2023 and May 2026 ¹⁸. The opposite error also circulates: a 2026 Swiss review states that it affects about one-third of cannabis users ¹²⁷, a figure that resembles the result of a convenience sample, people recruited because they were easy to reach rather than chosen to represent a population, of near-daily smokers defined by their response to hot showers ⁷³.

That it is a different drug's fault. Many patients reasonably suspect contaminants: in Russo's survey 6% blamed pesticides and 2% neem, a plant insecticide ³⁴. The same group's 2024 review rejects pesticide, neem oil and azadirachtin (the insecticidal compound in neem) explanations ⁴⁵. In the 2024 online survey 61.9% of respondents bought from licensed dispensaries and the source made no difference to the presentation ²⁴; living in a state with legal cannabis had no significant effect on self-reported symptoms ¹⁰; and synthetic cannabinoids, laboratory-made compounds not derived from the cannabis plant, can produce the same illness ^45,120. Nor is it confined to illicit or high-THC products. A French case report describes recurrent episodes, eased by hot showers, in a man who had switched from cannabis to daily cannabidiol and kept vomiting for six months without cannabis; his doctors call the link presumed and list THC stored in fat and conversion of cannabidiol to THC on burning among the possible explanations ¹²⁸. A 2026 Australian series of three young men prescribed medicinal cannabis by doctors lists the syndrome among the harms ¹²⁹, and a systematic review of delta-8-THC, a less intoxicating relative of THC sold without Food and Drug Administration regulation, lists it among the reported adverse effects ¹³⁰. These are case reports, not rates ^128,129,130. The other half of this belief, that the patient must simply have taken too much at once, has also failed: hair levels do not distinguish patients from regular users who do not vomit, and serum levels do not distinguish an attack from plain intoxication ^47,48.

That it resolves without stopping. In no series has it: the patients who continued in Allen's and the Michigan series stayed ill ^3,26, most relapses in Russo's survey followed resumed use ³⁴, and cutting down or switching products rather than stopping is the usual response described in the interview study ²¹. Each episode does end on its own, usually within about 48 hours of hyperemesis ²⁵, which is why every recovery can seem to prove the cannabis innocent.

That a hot shower proves it, and that ondansetron treats it. Hot bathing also relieves about half of people with cyclic vomiting syndrome who do not use cannabis ^12,85, and in the only randomized drug trial ondansetron did worse than haloperidol ¹³, although it remains the most used drug ⁷².

What is still unknown is most of the biology and much of the treatment. No one knows why only some heavy users develop it, when heavy use is necessary but not sufficient ⁴⁷; what threshold of dose, potency, route or duration matters ¹²; whether the candidate genes replicate ³⁴; how long abstinence must last before the diagnosis is secure ³⁷; or whether the syndrome and cyclic vomiting syndrome are one disease or two ^12,114. There is one randomized drug trial of 30 patients and one randomized capsaicin pilot of 30 ^13,55, and the emergency medicine guideline grades all of its advice for the syndrome at very low certainty ¹⁴. Even the epidemic curve is partly an artifact of coding, as the more than threefold jump when a dedicated code arrived in October 2025 shows ¹⁸. No retraction or expression of concern was found for any source cited on this page; one capsaicin cohort carries a 2024 corrigendum ⁹⁷.

The tests, one by one

• Rome IV criteria with a cannabis historyThe diagnosis rests on a pattern: stereotyped episodes resembling cyclic vomiting syndrome, onset after prolonged excessive cannabis use, and relief with sustained cessation, met for three months with onset at least six months earlier; hot bathing is only supportive ¹². Rome V (2026) keeps the category ².Every adult diagnosis; the 2025 pediatric guideline gives a consensus approach for children ⁵⁸Not validated against any test; only 59 of 376 published cases met it, mostly for missing follow-up ¹²Cannot separate the syndrome from cyclic vomiting syndrome in a cannabis user until abstinence has been observed ³⁷
• Observed abstinence, six to twelve monthsProposed criteria require resolution after at least six months without cannabis or three typical cycles, and one expert argues that twelve months is reliable ^12,37.Confirming a suspected case in outpatient follow-upConfounded by spontaneous remission, which occurs in half of children with cyclic vomiting syndrome after four years ¹²People who cannot or will not stop, who can only be called presumed cases ¹²
• Urine and blood cannabinoid testingA urine drug screen confirms recent use; it was positive in 86% of children with the syndrome against 2.9% of children with cyclic vomiting syndrome ²⁸.Emergency departments, to support the historyShows exposure, not disease: serum and hair cannabinoid levels do not distinguish patients from heavy users or from intoxicated patients ^47,48Whether cannabis is causing the vomiting
• Routine blood tests and imagingIn a Melbourne audit, a raised white count with neutrophils (stress-responsive white cells) in 75.8% and mild hypokalemia (low potassium) in 57.9%, with a normal lipase (a pancreatic enzyme) ²⁷; in a pediatric cohort, imaging was done in 36% and showed abnormalities in only 2.4% of the 125 patients ²⁸.Excluding surgical and metabolic causes and finding dehydration and low potassiumLow yield for the diagnosis; 72.2% of patients in one study had already had a computed tomography (CT) scan within five years ²⁹Another disease, once the label is attached, as with a missed superior mesenteric artery syndrome, in which an artery compresses the small intestine ⁶⁶

Where it connects

Sources

130 sources, numbered as they are cited. Every one was checked against PubMed or its publisher before it was cited here; the note under each says what it shows and what it does not.

1. 1
   Stanghellini V, Chan FKL, Hasler WL, Malagelada JR, Suzuki H, Tack J, Talley NJ. Gastroduodenal Disorders.Gastroenterology · 2016 · 150(6):1380-92doi:10.1053/j.gastro.2016.02.011 · PMID 27147122

   The Rome IV committee chapter that created cannabinoid hyperemesis syndrome as one of three nausea and vomiting disorders, beside chronic nausea and vomiting syndrome and cyclic vomiting syndrome. A consensus classification; the criteria text is quoted here from Venkatesan 2019, because the PubMed abstract lists only the categories.

2. 2
   Törnblom H, Carbone F, Hasler WL, Smout A, Suzuki H, Tack J, Talley NJ, Stanghellini V. Gastroduodenal Disorders.Gastroenterology · 2026 · 170(6):1240-1260doi:10.1053/j.gastro.2026.01.038 · PMID 41713705

   The Rome V chapter (2026): nausea and vomiting disorders still comprise chronic nausea vomiting syndrome, cyclic vomiting syndrome and cannabinoid hyperemesis syndrome. Only the classification is taken from the abstract; the revised criteria text was not available to this page.

3. 3
   Allen JH, de Moore GM, Heddle R, Twartz JC. Cannabinoid hyperemesis: cyclical hyperemesis in association with chronic cannabis abuse.Gut · 2004 · 53(11):1566-70doi:10.1136/gut.2003.036350 · PMID 15479672

   The first description. Nineteen South Australian patients identified, five refused consent and five were excluded for confounders, leaving nine plus one previously published case of 'psychogenic vomiting' that the authors reassigned to cannabis. Cessation ended the vomiting in seven; three who resumed relapsed; nine of ten showed abnormal washing behavior. A small case series without controls: it established the pattern and the dechallenge-rechallenge argument, not a mechanism or a frequency.

4. 4
   Hasler WL, Alshaarawy O, Venkatesan T. Cannabis use patterns and association with hyperemesis: A comprehensive review.Neurogastroenterology and Motility · 2025 · 37(3):e14895doi:10.1111/nmo.14895 · PMID 39164887

   Review: 40% to 80% of cyclic vomiting patients use cannabis; most CHS patients have used daily or near-daily for more than two years; hot-water bathing is reported by most CHS patients but by about half of cyclic vomiting patients; potency has risen; skepticism and perceived benefit hinder cessation. A review, not new data.

5. 5
   Sorensen CJ, DeSanto K, Borgelt L, Phillips KT, Monte AA. Cannabinoid Hyperemesis Syndrome: Diagnosis, Pathophysiology, and Treatment-a Systematic Review.Journal of Medical Toxicology · 2017 · 13(1):71-87doi:10.1007/s13181-016-0595-z · PMID 28000146

   Systematic review (January 2000 to September 2015) of 183 included articles graded with GRADE, a standard system for rating the certainty of evidence: regular cannabis use 100%, cyclic nausea and vomiting 100%, resolution after stopping 96.8%, compulsive hot baths 92.3%, abdominal pain 85.1%, male 72.9%, at least weekly use 97.4%. Pathophysiology unclear; fluids, dopamine antagonists and capsaicin of some benefit; cessation best. The pooled frequencies come almost entirely from case reports, which are selected for the classic picture.

6. 6
   Myran DT, Roberts R, Pugliese M, Taljaard M, Tanuseputro P, Pacula RL. Changes in Emergency Department Visits for Cannabis Hyperemesis Syndrome Following Recreational Cannabis Legalization and Subsequent Commercialization in Ontario, Canada.JAMA Network Open · 2022 · 5(9):e2231937doi:10.1001/jamanetworkopen.2022.31937 · PMID 36112372

   Interrupted time-series of all Ontario residents aged 15 and older, January 2014 to June 2021: 12,866 visits by 8140 people, mean age 27.4, 51.5% female, 8.8% admitted; monthly visits rose 13-fold (0.26 to 3.43 per 100,000). Legalization in October 2018 was not associated with a change; commercialization, which coincided with the pandemic, was (incidence rate ratio 1.49), more in women and in 19 to 24 year-olds. Administrative codes; pandemic and market change cannot be separated.

7. 7
   Swartz JA, Franceschini D. Cannabinoid Hyperemesis Syndrome, 2016 to 2022.JAMA Network Open · 2025 · 8(11):e2545310doi:10.1001/jamanetworkopen.2025.45310 · PMID 41284293

   Nationwide Emergency Department Sample, 188.6 million unweighted visits: a CHS proxy (a cannabis code plus a cyclic vomiting code) rose from 4.4 to a peak of 33.1 per 100,000 visits in the second quarter of 2020 and stayed at 22.3 in 2022, while cyclic vomiting without cannabis fell from 300 to 186; risk highest at 18 to 25 (relative risk ratio 3.59), lower in females (0.92). A proxy definition.

8. 8
   Toce MS, Monuteaux MC, Fishman MD, Hudgins JD. Emergency Department Visits for Cannabis Hyperemesis Syndrome Among Adolescents.JAMA Network Open · 2025 · 8(7):e2520492doi:10.1001/jamanetworkopen.2025.20492 · PMID 40658419

   Full text read. Children's hospital database, ages 13 to 21, 2016-2023: 4571 encounters, median age 17, 63.2% female; rate rose from 160.4 to 1968.3 per million emergency visits (49.0% a year), in states with and without recreational legalization; 41.1% admitted to a ward or observation unit and 0.6% to intensive care. Codes, children's hospitals only.

9. 9
   Ilgen MA, Price AM, Goldman P, Whittington BJ, Hicks BM. Prevalence and Correlates of Symptoms of Cannabinoid Hyperemesis Syndrome in the United States, 2025.American Journal of Public Health · 2026 · published online 1 October 2026, e1-e10doi:10.2105/AJPH.2026.308753 · PMID 42821817

   Nationally representative survey of 7034 adults, May to September 2025: 2.7% of all respondents and 17.8% of daily users reported CHS-like symptoms; younger, female, non-White, lower-income and less-educated respondents, and those with cannabis problems, were more likely to. Symptoms, not diagnoses.

10. 10
    Glodosky NC, Okey SA, Watson TD, Hammond D. Cannabinoid hyperemesis syndrome prevalence and risk factors in the U.S.International Journal on Drug Policy · 2026 · 153:105307doi:10.1016/j.drugpo.2026.105307 · PMID 42066407

    International Cannabis Policy Study survey, 2023, 10,255 United States cannabis users: about 6% reported past-year CHS; younger, male, Hispanic or multiracial respondents, and users of edibles and concentrates, were more likely to; using cannabis for nausea or headache was associated with it; living in a state with legal cannabis had no significant effect. Self-reported, self-defined; three authors work for the Washington State Liquor and Cannabis Board, a regulator.

11. 11
    Plebon-Huff S, Goodman S, Abramovici H. Trends in hospitalizations for cannabinoid hyperemesis syndrome in Canada, 2016-17 to 2024-25.Frontiers in Public Health · 2026 · 14:1740300doi:10.3389/fpubh.2026.1740300 · PMID 41908777

    Health Canada analysis of national discharge data: 7,533 hospitalizations; mean age 32.4; 52.1% male; rates rose about 2.5-fold from 1.5 to 3.8 per 100,000 between 2016-17 and 2024-25, mostly before 2020-21 with stabilization afterward; highest at ages 20 to 24, fastest rise at 45 to 64. Admissions only; authors are federal regulator staff.

12. 12
    Venkatesan T, Levinthal DJ, Li BUK, Tarbell SE, Adams KA, Issenman RM, Sarosiek I, Jaradeh SS, Sharaf RN, Sultan S, Stave CD, Monte AA, Hasler WL. Role of chronic cannabis use: Cyclic vomiting syndrome vs cannabinoid hyperemesis syndrome.Neurogastroenterology and Motility · 2019 · 31 Suppl 2:e13606doi:10.1111/nmo.13606 · PMID 31241817

    Full text read. The guideline committee for adult cyclic vomiting reproduced the Rome IV criteria, re-examined 25 case series (271 patients) and 105 case reports, and found that only 59 of 376 published cases (15.7%) met Rome IV, mostly because follow-up after stopping cannabis was absent. Proposed stricter criteria (more than four uses a week for over a year; resolution after at least six months or three cycles of abstinence), argued that CHS may be a subset of cyclic vomiting syndrome, noted hot bathing in about half of non-using cyclic vomiting patients, and warned against stigma. Several authors disclosed consulting for Takeda Pharmaceuticals, unrelated to cannabis. An expert systematic collation, not a cohort.

13. 13
    Ruberto AJ, Sivilotti MLA, Forrester S, Hall AK, Crawford FM, Day AG. Intravenous Haloperidol Versus Ondansetron for Cannabis Hyperemesis Syndrome (HaVOC): A Randomized, Controlled Trial.Annals of Emergency Medicine · 2021 · 77(6):613-619doi:10.1016/j.annemergmed.2020.08.021 · PMID 33160719

    Triple-blind randomized trial in Kingston, Ontario: 33 enrolled, 30 treated (13 haloperidol at 0.05 or 0.1 mg/kg, 17 ondansetron 8 mg). Haloperidol reduced combined pain and nausea by 2.3 cm more on 10-cm scales at 2 hours (95% confidence interval 0.6 to 4.0), with less rescue medication (31% versus 59%; difference -28%, 95% CI -61% to 13%, so not statistically certain) and earlier departure (3.1 versus 5.6 hours); two returned with acute dystonia, both on the higher dose. The only completed randomized drug trial for the acute episode; small.

14. 14
    Borgundvaag B, Bellolio F, Miles I, Schwarz ES, Sharif S, Su MK, Baumgartner K, Liss DB, Sheikh H, Vogel J, Austin EB, Upadhye S, Klaiman M, Vellend R, Munkley A, Carpenter CR. Guidelines for Reasonable and Appropriate Care in the Emergency Department (GRACE-4): Alcohol use disorder and cannabinoid hyperemesis syndrome management in the emergency department.Academic Emergency Medicine · 2024 · 31(5):425-455doi:10.1111/acem.14911 · PMID 38747203

    Society for Academic Emergency Medicine guideline using GRADE (a standard system for rating certainty of evidence): suggests haloperidol or droperidol, and offering topical capsaicin, in addition to usual care for adults with CHS, each at very low certainty of evidence. Patients with lived experience sat on the panel.

15. 15
    Nourbakhsh M, Miller A, Gofton J, Jones G, Adeagbo B. Cannabinoid Hyperemesis Syndrome: Reports of Fatal Cases.Journal of Forensic Sciences · 2019 · 64(1):270-274doi:10.1111/1556-4029.13819 · PMID 29768651

    Three deaths (a woman aged 27 and men aged 27 and 31) with histories of CHS and recent emergency visits; THC in postmortem blood; CHS judged the cause of death in two. Case reports from medical examiners.

16. 16
    von Both I, Santos B. Death of a young woman with cyclic vomiting: a case report.Forensic Science, Medicine and Pathology · 2021 · 17(4):715-722doi:10.1007/s12024-021-00410-z · PMID 34735682

    A 22-year-old with three and a half years of cyclic vomiting and cannabis use since age 14 developed torsades de pointes during emergency treatment and died of anoxic brain injury; death attributed to arrhythmia complicating vomiting-induced hypokalemia and QT-prolonging drugs (haloperidol and ondansetron were present), with cardiac gene variants contributing. One case.

17. 17
    Nay G, Selan J, Levi G, Nordenholz K, Kelly L. Cannabis Hyperemesis Syndrome in the Differential Diagnosis of Bathtub Deaths: Two Forensic Cases.American Journal of Forensic Medicine and Pathology · 2026 · published online 28 September 2026doi:10.1097/PAF.0000000000001176 · PMID 42802376

    Two men aged 38 and 44 with long-standing CHS found dead in bathtub or shower settings; investigative, autopsy, toxicology and vitreous chemistry findings discussed. Shows the interpretive difficulty; does not establish how often CHS causes such deaths.

18. 18
    Vivolo-Kantor AM, Liu S, Tanz LJ, Mattson CL, Schier J. Trends in Emergency Department Visits Involving Cannabis Hyperemesis Syndrome Identified Using a New Diagnosis Code - United States, January 2023-May 2026.MMWR Morbidity and Mortality Weekly Report · 2026 · 75(30):391-396doi:10.15585/mmwr.mm7530a2 · PMID 42560855

    CDC National Syndromic Surveillance Program: 199,565 CHS-involved emergency visits from January 2023 to May 2026; a CHS-specific code in the ICD-10-CM, the United States diagnostic coding system, took effect on 1 October 2025, after which the share rose from 3.35 to 11.26 per 10,000 visits in one month and averaged 3.7 times the earlier level; higher among people aged 15 to 24 and among females. The authors say the jump may partly reflect better coding rather than more disease.

19. 19
    Tramèr MR, Carroll D, Campbell FA, Reynolds DJ, Moore RA, McQuay HJ. Cannabinoids for control of chemotherapy induced nausea and vomiting: quantitative systematic review.BMJ · 2001 · 323(7303):16-21doi:10.1136/bmj.323.7303.16 · PMID 11440936

    Thirty randomized comparisons, 1366 patients, oral nabilone, oral dronabinol and intramuscular levonantradol: more effective than older antiemetics for complete control of nausea (relative risk 1.38, number needed to treat 6) and vomiting (1.28, 8), with more dizziness, dysphoria, paranoia and withdrawal for side effects. Predates modern antiemetics; no smoked cannabis.

20. 20
    Badowski ME. A review of oral cannabinoids and medical marijuana for the treatment of chemotherapy-induced nausea and vomiting: a focus on pharmacokinetic variability and pharmacodynamics.Cancer Chemotherapy and Pharmacology · 2017 · 80(3):441-449doi:10.1007/s00280-017-3387-5 · PMID 28780725

    Full text read. Dronabinol capsules, nabilone capsules and dronabinol oral solution are approved in the United States for chemotherapy nausea not controlled by conventional antiemetics; oral cannabinoids were first approved in the 1980s and the solution in July 2016; the solution's labeling warns that new or worsening nausea, vomiting and abdominal pain require dose reduction or discontinuation. A pharmacology review.

21. 21
    Copes H, Webb M, Valles J. Contesting Cannabinoid Hyperemesis Syndrome: How Narratives of Cannabis Shape Diagnosis Contestation and Treatment Resistance.Qualitative Health Research · 2025 · 35(8):876-886doi:10.1177/10497323241279079 · PMID 39455058

    Interviews with 24 people reporting CHS: positive beliefs about cannabis led them to contest the diagnosis (cannabis helps nausea, harms are a conspiracy, my symptoms differ) and to try new routes, products, smaller amounts or substitutes rather than stop. Qualitative; not a measure of how common these beliefs are.

22. 22
    Jiménez-Castillo RA, Arumugam S, Remes-Troche JM, Venkatesan T. Cannabinoid hyperemesis syndrome: A review.Revista de Gastroenterología de México (English Edition) · 2025 · 90(2):214-226doi:10.1016/j.rgmxen.2025.02.002 · PMID 40517066

    Review: published cases suggest an average of three to six years between the first episodes and the diagnosis; some authors diagnose CHS from cyclic vomiting plus cannabis regardless of duration or potency. Narrative review.

23. 23
    Seabrook JA, Seabrook M, Gilliland JA. Cannabis Hyperemesis Syndrome in Youth: Clinical Insights and Public Health Implications.International Journal of Environmental Research and Public Health · 2025 · 22(4):633doi:10.3390/ijerph22040633 · PMID 40283856

    Review of the syndrome in young people: the prodrome brings early-morning nausea that is often 'mistakenly alleviated' by more cannabis; recovery restores normal eating and bathing. Narrative review.

24. 24
    Peterson C, Simonian J, Mbengue M, Higgins J, Kirk R, Nava K, Lacinski R, Nelson A. Cannabinoid Hyperemesis Syndrome-A Survey-Based Approach to Understanding Symptoms and Cannabis Use Patterns.Cannabis and Cannabinoid Research · 2026 · 11(4):335-347doi:10.1177/25785125261421434 · PMID 41783912

    Anonymous online survey recruited from CHS social-media communities in late 2024, 1134 respondents: 96.5% used at least daily and 45% six or more times a day; 61.9% bought from licensed dispensaries, and source did not change the presentation; 65.4% had used for more than three years before symptoms; prodromal symptoms clustered in the morning (63.1%); vape cartridges were associated with a shorter time to onset; women reported more frequent and longer symptoms. Self-selected; several authors are affiliated with cannabis-nursing and pharmacognosy organizations.

25. 25
    Galli JA, Sawaya RA, Friedenberg FK. Cannabinoid hyperemesis syndrome.Current Drug Abuse Reviews · 2011 · 4(4):241-9doi:10.2174/1874473711104040241 · PMID 22150623

    Early review that set out the three clinical phases (prodromal, hyperemetic, recovery), noted that the hyperemetic phase usually ends within 48 hours, and called hot bathing a learned behavior. A narrative review based on case reports.

26. 26
    Soriano-Co M, Batke M, Cappell MS. The cannabis hyperemesis syndrome characterized by persistent nausea and vomiting, abdominal pain, and compulsive bathing associated with chronic marijuana use: a report of eight cases in the United States.Digestive Diseases and Sciences · 2010 · 55(11):3113-9doi:10.1007/s10620-010-1131-7 · PMID 20130993

    Eight patients at one Michigan hospital in 2009: mean 19 years from first use to vomiting, vomiting every 3 hours, five baths or showers a day totaling five hours, thirst in seven; four of five who stopped recovered, the three who continued stayed ill, and one relapsed on resuming. A small retrospective series with patient-reported follow-up.

27. 27
    Rotella JA, Ferretti OG, Raisi E, Seet HR, Sarkar S. Cannabinoid hyperemesis syndrome: A 6-year audit of adult presentations to an urban district hospital.Emergency Medicine Australasia · 2022 · 34(4):578-583doi:10.1111/1742-6723.13944 · PMID 35199462

    Melbourne chart review, 2015-2021: 142 presentations by 67 people, 68.7% male, median age 31; 29 re-presented, most within three months; raised white cell count with neutrophils in 75.8%, mild hypokalemia in 57.9%, normal lipase, C-reactive protein usually low; no deaths or intensive care admissions. Retrospective, one hospital.

28. 28
    Shah M, Jergel A, George RP, Jenkins E, Bashaw H. Distinguishing Clinical Features of Cannabinoid Hyperemesis Syndrome and Cyclic Vomiting Syndrome: A Retrospective Cohort Study.Journal of Pediatrics · 2024 · 271:114054doi:10.1016/j.jpeds.2024.114054 · PMID 38615942

    Retrospective pediatric cohort, 125 patients: those with CHS were older (18.1 versus 14.5 years), more often had a positive urine drug screen (86% versus 2.9%), lower potassium, higher creatinine and higher systolic pressure; no difference by sex; imaging in 36%, abnormal in 2.4%. Coded diagnoses, so the groups may overlap.

29. 29
    Heidish R, Loganathan A, Bolden T, Cooper Z, Barshay M, Lagunzad I, Meltzer AC. Patient-reported outcomes in cannabinoid hyperemesis syndrome patients treated in the emergency department: a pilot study.Clinical and Experimental Emergency Medicine · 2026 · 13(2):213-220 (published online 2 December 2025)doi:10.15441/ceem.25.032 · PMID 41327982

    Eighteen emergency patients with an established diagnosis: 72.2% had had a CT scan in the previous five years, 22.2% received opioids, and 16.7% returned within 30 days; anxiety and pain interference were high. Pilot.

30. 30
    Habboushe J, Sedor J. Cannabinoid hyperemesis acute renal failure: a common sequela of cannabinoid hyperemesis syndrome.American Journal of Emergency Medicine · 2014 · 32(6):690.e1-2doi:10.1016/j.ajem.2013.12.013 · PMID 24418446

    Case (25-year-old, creatinine 3.21) plus literature count: the authors found five other reports of acute renal failure among 55 published CHS case reports and attributed it to vomiting combined with constant hot showers. Case-report arithmetic, not a rate.

31. 31
    Hayat U, Al-Sawalha MK, Hussain S. Alcohol as a Novel Trigger for Cannabis Hyperemesis Syndrome.Cureus · 2026 · 18(1):e102439doi:10.7759/cureus.102439 · PMID 41769444

    A 52-year-old with five episodes, each about a week after a single dose of alcohol, the last complicated by life-threatening hyponatremia needing intensive care. One case; the trigger claim is the authors' inference.

32. 32
    Jafry B, Chillag S. Spontaneous Pneumomediastinum and Cannabinoid Hyperemesis Syndrome: A Case Report and Literature Review.Cureus · 2026 · 18(1):e101979doi:10.7759/cureus.101979 · PMID 41728401

    An 18-year-old with air in the mediastinum after forceful vomiting, no esophageal perforation, managed conservatively; described as one of only five reported cases of this association. Case report.

33. 33
    Abes J, Bou Jaoude M, Landrum T, McGill J. Wernicke Encephalopathy Secondary to Cannabinoid Hyperemesis Syndrome in a 15-Year-Old Male Patient: A Case Report.Cureus · 2026 · 18(8):e115093doi:10.7759/cureus.115093 · PMID 42781598

    A 15-year-old lost 25 to 30 pounds, developed confusion, ataxia and nystagmus with a normal brain MRI; confirmed thiamine deficiency; improvement within a day of thiamine and full recovery after stopping cannabis. One case.

34. 34
    Russo EB, Spooner C, May L, Leslie R, Whiteley VL. Cannabinoid Hyperemesis Syndrome Survey and Genomic Investigation.Cannabis and Cannabinoid Research · 2022 · 7(3):336-344doi:10.1089/can.2021.0046 · PMID 34227878

    Full text read. An online survey recruited through cannabis list-serves and the Society of Cannabis Clinicians (585 respondents, 205 qualifying patients, 54 controls); only 28 patients and 12 controls returned genotyping kits. Variants in COMT (57.1% of patients versus 10% of controls, odds ratio 12), ABCA1 (8.4), TRPV1 (5.8), DRD2 (6.2) and CYP2C9 (7.8) were reported by Fisher's exact test without a stated correction for multiple comparisons; CNR1, the gene the authors predicted, was not significant. The introduction also gives the authors' account that Allen's index case dated to 1996 and that recovery follows a long phase structure. Two of five authors list Endocanna Health, a commercial genomics company, and the paper proposes the variants as a future diagnostic battery: a commercial interest in the finding. Entry to the patient pool required abdominal pain alleviated by hot showers or baths, so the report that 100% were better after hot water follows from the selection rule. The COMT confidence interval is 1.3-88.1 in the abstract and text but 1.3-98.1 in Table 2. Hypothesis-generating; unreplicated.

35. 35
    Meyer J, Burns MM. Current recommendations in the diagnosis and management of cannabinoid hyperemesis syndrome.Current Opinion in Pediatrics · 2025 · 37(3):240-243doi:10.1097/MOP.0000000000001464 · PMID 40172286

    Pediatric review: since the 2004 identification of the syndrome, the only known treatment has been complete cessation of all THC-containing products; dopamine antagonists may help acutely; anxiety, depression and substance use disorder need treatment. A narrative review, not new data.

36. 36
    Yacob D. Cyclic Vomiting Syndrome and Cannabinoid Hyperemesis Syndrome: Their Intersection and Joint Existence.Gastroenterology Clinics of North America · 2025 · 54(3):557-568doi:10.1016/j.gtc.2025.05.004 · PMID 40752916

    Review arguing that the two disorders share a phase structure (prodromal, emetic, recovery and interepisodic) but differ in pathophysiology, epidemiology and management, cyclic vomiting being tied to migraine and autonomic dysfunction and CHS directly to heavy cannabis use. Opinion and synthesis.

37. 37
    Bonnet U. Cannabis hyperemesis syndrome: the rare case of a valid diagnosis plus hypersensitization hypothesis for development and chronification of this severe somatic cannabis use disorder.Fortschritte der Neurologie-Psychiatrie · 2026 · published online 28 January 2026doi:10.1055/a-2731-3369 · PMID 41605419

    Case report and hypothesis: the only criterion separating CHS from cyclic vomiting syndrome is lasting disappearance of symptoms during abstinence, 12 months of observation is diagnostically reliable, and most published cases are therefore only suspected CHS. Describes each relapse as stronger than the last and proposes a hypersensitization mechanism. One case and an idea, not a test of it.

38. 38
    Hirvonen J, Goodwin RS, Li CT, Terry GE, Zoghbi SS, Morse C, Pike VW, Volkow ND, Huestis MA, Innis RB. Reversible and regionally selective downregulation of brain cannabinoid CB1 receptors in chronic daily cannabis smokers.Molecular Psychiatry · 2012 · 17(6):642-9doi:10.1038/mp.2011.82 · PMID 21747398

    Positron emission tomography in chronic daily smokers: cortical CB1 receptors were reduced in proportion to years of smoking and returned to normal after about four weeks of monitored abstinence. Human imaging of tolerance; it did not study vomiting.

39. 39
    Parker LA, Rock EM, Limebeer CL. Regulation of nausea and vomiting by cannabinoids.British Journal of Pharmacology · 2011 · 163(7):1411-22doi:10.1111/j.1476-5381.2010.01176.x · PMID 21175589

    Review of animal work: stimulating the CB1 receptor suppresses vomiting in species that can vomit and blocking it reverses the effect; inverse agonists of CB1 promote nausea and vomiting; rats and mice cannot vomit, so 'gaping' is used as a proxy. Animal evidence only.

40. 40
    Richards JR, Lapoint JM, Burillo-Putze G. Cannabinoid hyperemesis syndrome: potential mechanisms for the benefit of capsaicin and hot water hydrotherapy in treatment.Clinical Toxicology · 2018 · 56(1):15-24doi:10.1080/15563650.2017.1349910 · PMID 28730896

    Mechanistic review: TRPV1 responds to heat above 43 degrees Celsius, acid below pH 6 and capsaicin; topical capsaicin had been used in some 20 reported cases; heat or capsaicin may desensitize TRPV1 and alter neuropeptide signaling. Theory assembled from pharmacology, not tested in patients.

41. 41
    Zygmunt PM, Petersson J, Andersson DA, Chuang H, Sørgård M, Di Marzo V, Julius D, Högestätt ED. Vanilloid receptors on sensory nerves mediate the vasodilator action of anandamide.Nature · 1999 · 400(6743):452-7doi:10.1038/22761 · PMID 10440374

    Isolated animal arteries and cells expressing the cloned receptor: the body's own cannabinoid anandamide activates the capsaicin receptor (now TRPV1). In vitro evidence that links the endocannabinoid and TRPV1 systems; says nothing about vomiting.

42. 42
    Dezieck L, Hafez Z, Conicella A, Blohm E, O'Connor MJ, Schwarz ES, Mullins ME. Resolution of cannabis hyperemesis syndrome with topical capsaicin in the emergency department: a case series.Clinical Toxicology · 2017 · 55(8):908-913doi:10.1080/15563650.2017.1324166 · PMID 28494183

    Thirteen daily cannabis users at two academic centers, all reporting relief after capsaicin cream once other treatments had failed; proposes that capsaicin overstimulates TRPV1 and impairs substance P signaling in the area postrema and nucleus tractus solitarius. Uncontrolled retrospective series, selected by the fact that capsaicin was given.

43. 43
    Louis-Gray K, Tupal S, Premkumar LS. TRPV1: A Common Denominator Mediating Antinociceptive and Antiemetic Effects of Cannabinoids.International Journal of Molecular Sciences · 2022 · 23(17):10016doi:10.3390/ijms231710016 · PMID 36077412

    Review of how cannabinoids act on TRPV1 in pain and vomiting pathways; proposes that hot water and capsaicin both act on TRPV1 in the vagal, nucleus tractus solitarius and area postrema circuitry. Hypothesis from basic science.

44. 44
    Venkatesan T, Zadvornova Y, Raff H, Hillard CJ. Endocannabinoid-related lipids are increased during an episode of cyclic vomiting syndrome.Neurogastroenterology and Motility · 2016 · 28(9):1409-18doi:10.1111/nmo.12843 · PMID 27098832

    Twenty-two cyclic vomiting patients and 12 controls: endocannabinoids themselves did not differ, related lipids rose during episodes, and salivary cortisol and alpha amylase were higher in marijuana users than non-users during the sick phase. A small subgroup finding that generated the stress-response hypothesis.

45. 45
    Russo EB, Whiteley VL. Cannabinoid hyperemesis syndrome: genetic susceptibility to toxic exposure.Frontiers in Toxicology · 2024 · 6:1465728doi:10.3389/ftox.2024.1465728 · PMID 39507417

    Review by the same group: associates the syndrome with hypothalamic-pituitary-adrenal activation, escalating high-potency cannabis or synthetic cannabinoids and conditioned triggers; restates the five variants; rejects pesticide, neem oil and azadirachtin explanations; holds cyclic vomiting syndrome to be clearly distinct. Narrative review of the authors' own work; no new data, no replication.

46. 46
    DeVuono MV, Venkatesan T, Hillard CJ. Endocannabinoid signaling in stress, nausea, and vomiting.Neurogastroenterology and Motility · 2025 · 37(3):e14911doi:10.1111/nmo.14911 · PMID 39223918

    Review: cannabinoids are antiemetic and anxiolytic at some doses but can produce nausea, vomiting and anxiety at higher doses; proposes that prolonged use dysregulates the endocannabinoid and stress systems. Mostly animal and indirect human evidence.

47. 47
    Albert K, Sivilotti MLA, Gareri J, Day A, Ruberto AJ, Hookey LC. Hair cannabinoid concentrations in emergency patients with cannabis hyperemesis syndrome.CJEM · 2019 · 21(4):477-481doi:10.1017/cem.2018.479 · PMID 30806339

    Case-control study: 16 patients, 16 heavy users without vomiting and 14 unrelated emergency patients. Scalp-hair THC was similar across groups (median 220, 150 and 270 pg/mg); only the THC to cannabinol ratio differed. Concludes heavy use is necessary but not sufficient. Small.

48. 48
    Toomey D, Merchant-Borna K, Krotulski AJ, Baker S, Zhang V, Nacca N. Serum cannabinoid profiles of emergency department patients presenting with cannabinoid hyperemesis syndrome and acute cannabis intoxication.Clinical Toxicology · 2026 · 64(10):881-887doi:10.1080/15563650.2026.2703873 · PMID 42504769

    Retrospective cohort, 35 CHS and 15 intoxication patients, mass spectrometry of remnant serum: no differences in THC, its metabolites, delta-8-THC, cannabidiol, cannabigerol, cannabinol or their ratios. Argues against accumulation or a particular cannabinoid mix as the cause of an attack; single center, timing of last use uncontrolled. A letter of comment followed (Clinical Toxicology 2026; 64(10):970-971).

49. 49
    Bloom J, Beaudoin FL, Lin TR, Gaipo A, Ortega C, Wightman RS. Cannabis Use Patterns and Blood Profiles in Adolescent Cannabinoid Hyperemesis Syndrome.Pediatric Emergency Care · 2026 · 42(1):e13-e19 (published online 16 October 2025)doi:10.1097/PEC.0000000000003495 · PMID 41088881

    Pilot prospective cohort: 869 adolescents screened, 10 enrolled aged 14 to 21; all had cannabis use disorder or hazardous use and described withdrawal; blood 11-hydroxy-THC was lower when symptomatic (median 0.6 ng/mL) than at a well visit (4.2 ng/mL); vitamins and minerals were normal. Ten people.

50. 50
    de Moore GM, Baker J, Bui T. Psychogenic vomiting complicated by marijuana abuse and spontaneous pneumomediastinum.Australian and New Zealand Journal of Psychiatry · 1996 · 30(2):290-4doi:10.3109/00048679609076108 · PMID 8811275

    Department of Psychiatry, Westmead Hospital, New South Wales: a 22-year-old man with psychogenic vomiting and marijuana use developed pneumomediastinum and subcutaneous emphysema; treated with exposure therapy, psychotropic drugs and family psychotherapy; improved at 12 months with occasional less severe vomiting. Its first author is the second author of Allen 2004, and its year matches Russo's 1996 index-case date, so it is probably the published case of psychogenic vomiting that Allen's group reassigned; the 2004 abstract does not name it. One case.

51. 51
    Chepyala P, Olden KW. Cyclic vomiting and compulsive bathing with chronic cannabis abuse.Clinical Gastroenterology and Hepatology · 2008 · 6(6):710-2doi:10.1016/j.cgh.2008.01.017 · PMID 18456571

    Single United States case in which staff observed the compulsive showering; vomiting, pain and showering stopped after a drug rehabilitation program and abstinence. Anecdote.

52. 52
    Simonetto DA, Oxentenko AS, Herman ML, Szostek JH. Cannabinoid hyperemesis: a case series of 98 patients.Mayo Clinic Proceedings · 2012 · 87(2):114-9doi:10.1016/j.mayocp.2011.10.005 · PMID 22305024

    Largest early series (Mayo Clinic, 2005-2010): 98 patients, all younger than 50; 95% of those with data used more than weekly; abdominal pain 86%; 52 of 57 asked reported relief from hot bathing; follow-up in only 10, of whom 7 stopped and 6 resolved. Proposed major and supportive criteria. Follow-up too sparse to confirm the diagnosis in most patients.

53. 53
    Bhandari S, Venkatesan T. Novel Treatments for Cyclic Vomiting Syndrome: Beyond Ondansetron and Amitriptyline.Current Treatment Options in Gastroenterology · 2016 · 14(4):495-506doi:10.1007/s11938-016-0114-y · PMID 27757817

    Review with Thangam Venkatesan as senior author. Its abstract calls cannabinoid hyperemesis syndrome a possible new diagnosis that is 'indistinguishable from CVS' and a 'purported condition' whose treatment, abstinence, rests on 'scant evidence that marijuana use is causative'. Cited for the skepticism expressed in the year of codification.

54. 54
    Venkatesan T, Hasler WL, Camilleri M. Cannabinoid Hyperemesis Syndrome.JAMA · 2026 · published online 26 August 2026doi:10.1001/jama.2026.7873 · PMID 42647032

    A 2026 JAMA clinical review by gastroenterologists who have led the field. No abstract in PubMed and the text was not available to this page; cited only to date the syndrome's arrival in a general-medicine review, not for content.

55. 55
    Dean DJ, Sabagha N, Rose K, Weiss A, France J, Asmar T, Rammal JA, Beyer M, Bussa R, Ross J, Chaudhry K, Smoot T, Wilson K, Miller J. A Pilot Trial of Topical Capsaicin Cream for Treatment of Cannabinoid Hyperemesis Syndrome.Academic Emergency Medicine · 2020 · 27(11):1166-1172doi:10.1111/acem.14062 · PMID 32569429

    Double-blind, placebo-controlled pilot in Detroit: 30 patients (17 capsaicin 0.1%, 13 placebo cream on the abdomen). Nausea at 30 minutes 4.1 versus 6.1 cm (difference not significant); at 60 minutes 3.2 versus 6.4 cm (difference -3.2 cm, 95% confidence interval -0.9 to -5.4); complete resolution 29.4% versus 0%; one patient stopped for skin irritation. The only randomized capsaicin trial found for this page; a pilot.

56. 56
    Humphries C, Gillings M. RCEM best practice guideline: suspected cannabinoid hyperemesis syndrome in emergency departments.Emergency Medicine Journal · 2024 · 41(5):328-331doi:10.1136/emermed-2024-213886 · PMID 38448215

    Royal College of Emergency Medicine (United Kingdom) toxicology guidance on recognition, investigation and communication, recommending treatment options that include haloperidol and capsaicin on the best available evidence. Expert guidance.

57. 57
    Rubio-Tapia A, McCallum R, Camilleri M. AGA Clinical Practice Update on Diagnosis and Management of Cannabinoid Hyperemesis Syndrome: Commentary.Gastroenterology · 2024 · 166(5):930-934.e1doi:10.1053/j.gastro.2024.01.040 · PMID 38456869

    American Gastroenterological Association expert commentary, peer reviewed internally and externally, giving advice on diagnosis and management. Only its existence and nature are cited here: the PubMed abstract gives no recommendations, and the full text was not available to this page.

58. 58
    Karrento K, Rosen JM, Gelfand AA, Parikh S, Tarbell SE, Issenman RM, Gamboa H, Adams K, Wiercioch W, Li BUK. North American Society for Pediatric Gastroenterology, Hepatology, and Nutrition 2025 guidelines on the diagnosis of cyclic vomiting syndrome in children.Journal of Pediatric Gastroenterology and Nutrition · 2025 · 81(5):1346-1359doi:10.1002/jpn3.70193 · PMID 40836301

    Pediatric diagnostic guideline using GRADE evidence rating and Delphi (structured expert) consensus; provides a consensus-based approach to pediatric CHS 'as a related but separate entity'.

59. 59
    Rech MA, Shalaby M, Gage KA, Gottlieb M. Managing Cannabinoid Hyperemesis Syndrome.Annals of Emergency Medicine · 2026 · 87(6):717-722doi:10.1016/j.annemergmed.2025.12.024 · PMID 41632059

    2026 emergency medicine review. No abstract in PubMed; cited only as part of the 2024-2026 run of reviews in the history section, not for specific claims.

60. 60
    Sallan SE, Zinberg NE, Frei E. Antiemetic effect of delta-9-tetrahydrocannabinol in patients receiving cancer chemotherapy.New England Journal of Medicine · 1975 · 293(16):795-7doi:10.1056/NEJM197510162931603 · PMID 1099449

    Randomized, double-blind crossover of oral THC against placebo in chemotherapy: an antiemetic effect in 14 of 20 THC courses and none of 22 placebo courses. Twenty evaluable patients; the founding trial of cannabinoid antiemesis.

61. 61
    Kim HS, Anderson JD, Saghafi O, Heard KJ, Monte AA. Cyclic vomiting presentations following marijuana liberalization in Colorado.Academic Emergency Medicine · 2015 · 22(6):694-9doi:10.1111/acem.12655 · PMID 25903855

    Cross-sectional chart review in Denver: cyclic vomiting visits rose from 41 per 113,262 to 87 per 125,095 emergency visits after the 2009 liberalization of medical marijuana (prevalence ratio 1.92), and documented marijuana use rose (odds ratio 3.59). The authors could not say whether use or reporting had changed. Small absolute numbers; association only.

62. 62
    Kilani Y, Nguyen C, Mosquera DAG, Ferreira MN, Aldiabat M, Madi MY, Levinthal DJ, Farmer AD. Cannabis Use Is Associated With Increased Healthcare Utilization and Poorer Outcomes in Cyclical Vomiting Syndrome-A Propensity Matched Analysis of 34,988 Individuals.Neurogastroenterology and Motility · 2026 · 38(4):e70263doi:10.1111/nmo.70263 · PMID 41935343

    Retrospective cohort in the TriNetX records network: 18,588 adults with cyclic vomiting syndrome who used cannabis were propensity-matched 1:1 on demographics, body mass index, comorbidities and treatments with 18,588 who did not. Users were younger (31.9 versus 39.0 years), more often received abortive and less often preventive therapy, and had more emergency visits (hazard ratio 1.35, 95% CI 1.31-1.39) and hospitalizations (1.11, 1.06-1.16). Points the other way from the same first author's 2024 inpatient analysis; administrative data, association only.

63. 63
    Kilani Y, Aljabiri Y, Arshad I, Alsakarneh S, Aldiabat M, Castro Puello P, Vahanyan A, Vikash F, Kumar V, Numan L, Thor S. Cannabis use and cyclical vomiting syndrome: An open debate.Digestive and Liver Disease · 2024 · 56(2):272-280doi:10.1016/j.dld.2023.10.002 · PMID 37880016

    National Inpatient Sample, 35,055 cyclic vomiting admissions: cannabis use was associated with shorter stays and fewer 30-day readmissions, which the authors suggest may reflect hidden CHS admissions and the effect of stopping; they called for CHS-specific codes. A 2026 propensity-matched study led by the same first author found the opposite direction for emergency visits and hospitalizations. Administrative data.

64. 64
    Korn F, Hammerich S, Gries A. [Cannabinoid hyperemesis as a differential diagnosis of nausea and vomiting in the emergency department].Anaesthesist · 2021 · 70(2):158-160doi:10.1007/s00101-020-00850-2 · PMID 33090239

    German case: diagnosis made on the fourth presentation, after a normal abdominal CT and gastroscopy; symptoms resolved completely six months into abstinence. One case.

65. 65
    Akturk HK, Mason E, Snell-Bergeon J, Shah VN, Karakus KE. Differentiating Diabetic Gastroparesis and Cannabis Hyperemesis Syndrome in People With Type 1 Diabetes.Clinical Diabetes · 2025 · 43(3):416-419doi:10.2337/cd24-0096 · PMID 40741458

    In people with type 1 diabetes, older age, longer diabetes, female sex, lower A1C (a measure of average blood sugar) and neuropathy favored diabetic gastroparesis over CHS. A single-center comparison.

66. 66
    Knight HE, Singla A, Smerina M, Cortes MP, Gavrancic T, Baumgarten DA, Dumitrascu AG, Pagan RJ, Murawska Baptista A. A Rare Complication of Cannabinoid Hyperemesis Syndrome.American Journal of Case Reports · 2024 · 25:e945106doi:10.12659/AJCR.945106 · PMID 39375911

    An adolescent with prior THC-associated hyperemesis and a 21-kg weight loss over six months was eventually found to have superior mesenteric artery syndrome; a case about premature attribution of symptoms to a known diagnosis.

67. 67
    Monte AA, Shelton SK, Mills E, Saben J, Hopkinson A, Sonn B, Devivo M, Chang T, Fox J, Brevik C, Williamson K, Abbott D. Acute Illness Associated With Cannabis Use, by Route of Exposure: An Observational Study.Annals of Internal Medicine · 2019 · 170(8):531-537doi:10.7326/M18-2809 · PMID 30909297

    Chart review at a Colorado academic hospital, 2012-2016: of 2567 visits at least partly attributable to cannabis, those from inhaled cannabis were more often for CHS (18.0%) than those from edibles (8.4%). Single center; self-reported route.

68. 68
    Bouquet E, Pain S, Eiden C, Jouanjus E, Richard N, Fauconneau B, Pérault-Pochat MC. Adverse events of recreational cannabis use reported to the French addictovigilance network (2012-2017).British Journal of Clinical Pharmacology · 2021 · 87(10):3925-3937doi:10.1111/bcp.14812 · PMID 34282851

    French national addictovigilance reports, 2217 cases: CHS appeared from 2015 and accounted for 87 adverse events (2.8% of all adverse events recorded). Spontaneous reporting, which counts recognition as much as disease.

69. 69
    Andrews CN, Rehak R, Woo M, Walker I, Ma C, Forbes N, Rittenbach K, Hathaway J, Wilsack L, Liu A, Nasser Y, Sharkey KA. Cannabinoid hyperemesis syndrome in North America: evaluation of health burden and treatment prevalence.Alimentary Pharmacology and Therapeutics · 2022 · 56(11-12):1532-1542doi:10.1111/apt.17265 · PMID 36307209

    Internet survey of 157 people with CHS (problematic use on a standard screening test was universal; 59% screened for moderate or worse anxiety, 68% for depression) plus Alberta records: emergency visits for vomiting with a cannabis code rose from 15 to 21 to 32 per 100,000 across the year before legalization, the year after, and the first pandemic year; up to 6 per 1000 chronic users aged 16 to 24. A coding proxy and a self-selected survey.

70. 70
    Miki A, Tandon M, Murad D, Loughman J, Gilman J, Jangi S. Increasing Prevalence of Cannabinoid Hyperemesis Syndrome in Young Adults and Minority Populations.American Journal of Gastroenterology · 2025 · 120(12):2954-2956doi:10.14309/ajg.0000000000003591 · PMID 40511929

    Massachusetts all-payer data, over 15 million emergency visits, 2012-2021: CHS rose from 0.729 to 10.6 per 10,000 visits, fastest at ages 18 to 34, highest among young adults, Hispanic and Black people and men. Brief report on coded visits.

71. 71
    Jack B, Susi A, Reeves P, Nylund CM. Increasing trends of cannabinoid hyperemesis syndrome in youth: The grass is not always greener.Journal of Pediatric Gastroenterology and Nutrition · 2025 · 80(4):638-643doi:10.1002/jpn3.12469 · PMID 39868747

    Nationwide emergency sample, ages 15 to 24, 2006-2020: over 55,000 suspected CHS visits, rising 28.1% a year on average; more likely in the West, in males and with public insurance. Suspected cases by codes.

72. 72
    Shalaby M, Moyer E, Buell KG, Bernard K, Gottlieb M. Presentations to United States emergency departments for gastroparesis, cyclic vomiting, and cannabinoid hyperemesis syndrome from 2016 to 2024.American Journal of Emergency Medicine · 2025 · 96:201-207doi:10.1016/j.ajem.2025.06.067 · PMID 40602005

    Epic Cosmos records of 248,293,507 emergency encounters: 134,059 (0.05%) coded as CHS; mean age 32; admission about 13.5%, mean stay 3.8 days; ondansetron the most used drug (58.7%), haloperidol second (32.6%); the three conditions 'primarily affected females'. Coding-based, before the specific code existed.

73. 73
    Habboushe J, Rubin A, Liu H, Hoffman RS. The Prevalence of Cannabinoid Hyperemesis Syndrome Among Regular Marijuana Smokers in an Urban Public Hospital.Basic and Clinical Pharmacology and Toxicology · 2018 · 122(6):660-662doi:10.1111/bcpt.12962 · PMID 29327809

    Convenience sample at a New York public hospital: of 2127 patients aged 18 to 49 approached, 155 smoked on at least 20 days a month, and 32.9% (95% confidence interval 25.5 to 40.3) met the authors' definition, which rested on rating hot showers at least 5 of 10 for relief of nausea and vomiting; extrapolated to about 2.75 million Americans. The definition did not require episodic vomiting, and the 2019 guideline review judged the figure an overestimate.

74. 74
    Ilgen MA, Price AM, Goldman P, Hicks BM. Prevalence and Correlates of Symptoms of Cannabinoid Hyperemesis Syndrome in the United States.medRxiv (preprint) · 2026 · posted 26 January 2026doi:10.64898/2026.01.25.26344780 · PMID 41646674

    Preprint of the American Journal of Public Health paper, not peer reviewed in this form: 15.2% reported daily use in the past five years; only 11.5% of those with a CHS-consistent symptom profile said a clinician had diagnosed it. Used here only for the diagnosis figure, which the published abstract does not give.

75. 75
    Meltzer AC, Morrison C, Loganathan A, Shahamatdar S, Moon A, Heidish R, Makutonin M, Ma Y, Li R, Cooper ZD. Cannabinoid Hyperemesis Syndrome Is Associated With High Disease Burden: An Internet-Based Survey.Annals of Emergency Medicine · 2025 · 85(6):521-525doi:10.1016/j.annemergmed.2025.01.008 · PMID 39985554

    Online support-group survey of 1052 people with self-reported CHS: most used frequently and many had emergency visits and admissions; heavy daily use and starting in adolescence were associated with more frequent episodes. Self-selected sample.

76. 76
    Grimison P, Mersiades A, Kirby A, Lintzeris N, Morton R, Haber P, Olver I, Walsh A, McGregor I, Cheung Y, Tognela A, Hahn C, Briscoe K, Aghmesheh M, Fox P, Abdi E, Clarke S, Della-Fiorentina S, Shannon J, Gedye C, Begbie S, Simes J, Stockler M. Oral THC:CBD cannabis extract for refractory chemotherapy-induced nausea and vomiting: a randomised, placebo-controlled, phase II crossover trial.Annals of Oncology · 2020 · 31(11):1553-1560doi:10.1016/j.annonc.2020.07.020 · PMID 32801017

    Phase II crossover, 81 randomized, 72 analyzed: complete response rose from 14% to 25% with THC 2.5 mg/CBD 2.5 mg capsules added to standard antiemetics (relative risk 1.77, 90% confidence interval 1.12 to 2.79); 31% had moderate or severe cannabinoid side effects; 83% preferred the extract. Modern evidence that THC is antiemetic at modest, intermittent doses.

77. 77
    Loganathan P, Gajendran M, Goyal H. A Comprehensive Review and Update on Cannabis Hyperemesis Syndrome.Pharmaceuticals (Basel) · 2024 · 17(11):1549doi:10.3390/ph17111549 · PMID 39598458

    Review describing the endocannabinoid system's dose-dependent dual response (antiemetic at low doses, proemetic at higher doses) and suggesting that the thermoregulatory function of endocannabinoids might explain hot bathing. Narrative review.

78. 78
    ElSohly MA, Mehmedic Z, Foster S, Gon C, Chandra S, Church JC. Changes in Cannabis Potency Over the Last 2 Decades (1995-2014): Analysis of Current Data in the United States.Biological Psychiatry · 2016 · 79(7):613-9doi:10.1016/j.biopsych.2016.01.004 · PMID 26903403

    Analysis of 38,681 cannabis samples seized by the Drug Enforcement Administration: THC rose from about 4% in 1995 to about 12% in 2014 and the THC to CBD ratio from 14 to about 80. Illicit seized material, not legal-market products; says nothing directly about vomiting.

79. 79
    ElSohly MA, Chandra S, Radwan M, Majumdar CG, Church JC. A Comprehensive Review of Cannabis Potency in the United States in the Last Decade.Biological Psychiatry: Cognitive Neuroscience and Neuroimaging · 2021 · 6(6):603-606doi:10.1016/j.bpsc.2020.12.016 · PMID 33508497

    14,234 herbal cannabis samples seized by the Drug Enforcement Administration, 2009-2019: mean THC rose from 9.75% in 2009 to 14.88% in 2018 and 13.88% in 2019; the THC:CBD ratio rose from 24.81 in 2009 to 103.48 in 2017, then fell to 54.39 in 2018 and 24.58 in 2019 as higher-CBD chemovars appeared. Seized illicit flower only, with falling sample numbers after legalization.

80. 80
    Venkatesan T, Hillard CJ, Rein L, Banerjee A, Lisdahl K. Patterns of Cannabis Use in Patients With Cyclic Vomiting Syndrome.Clinical Gastroenterology and Hepatology · 2020 · 18(5):1082-1090.e2doi:10.1016/j.cgh.2019.07.039 · PMID 31352091

    Cross-sectional study of 140 cyclic vomiting patients at a specialist clinic: 41% current cannabis users, 21% regular (four or more times a week); most users said cannabis helped; 50 of 57 had abstained for more than a month but only one had episodes stop. The one patient whose episodes stopped later resumed cannabis and remained free of symptoms. Abstinence was self-reported, against a one-month threshold far shorter than the six months later proposed; a specialist cohort, not the emergency population.

81. 81
    Wasilewski A, Lewandowska U, Mosinska P, Watala C, Storr M, Fichna J, Venkatesan T. Cannabinoid Receptor Type 1 and mu-Opioid Receptor Polymorphisms Are Associated With Cyclic Vomiting Syndrome.American Journal of Gastroenterology · 2017 · 112(6):933-939doi:10.1038/ajg.2017.73 · PMID 28349993

    Case-control study of 65 cyclic vomiting patients against 1,092 public-genome controls: CNR1 rs806380 AG and GG genotypes carried higher risk. Concerns cyclic vomiting, not CHS; controls not matched clinically.

82. 82
    Bashashati M, Bradshaw HB, Johnson CT, Zuckerman MJ, Sarosiek J, McCallum RW, Sarosiek I. Plasma endocannabinoids and cannabimimetic fatty acid derivatives are altered in cyclic vomiting syndrome: The effects of sham feeding.Journal of Investigative Medicine · 2023 · 71(8):821-829doi:10.1177/10815589231196591 · PMID 37572030

    Ten cyclic vomiting patients and eight controls: baseline 2-arachidonoylglycerol was higher in patients, anandamide was not different, and parasympathetic tone was lower. A small study of cyclic vomiting, not CHS.

83. 83
    Bonnet U. [Cannabinoid Hyperemesis Syndrome: A Scoping Review].Fortschritte der Neurologie-Psychiatrie · 2025 · published online 12 November 2025doi:10.1055/a-2704-5465 · PMID 41224199

    German scoping review (English abstract): about 30% of cyclic vomiting patients use cannabis chronically; distinguishing the two requires at least six months of abstinence; haloperidol up to 5 mg intramuscularly and 0.075-0.1% capsaicin help; after several clusters relapses, even at low doses, bring stronger, longer clusters; cure means full remission for at least five years. Expert synthesis.

84. 84
    Wightman RS, Perrone J, Collins AB, Lakamana S, Sarker A. An analysis of cannabinoid hyperemesis syndrome Reddit posts and themes.Clinical Toxicology · 2023 · 61(4):283-289doi:10.1080/15563650.2023.2183790 · PMID 37014024

    Machine-assisted analysis of 2683 Reddit posts (2018-2022): the most mentioned triggers were food and drink, cannabinoids, stress and alcohol; the most mentioned remedies were hot water (62 posts), hydration and antiemetics. Online self-report.

85. 85
    Rosen S, Diaz R, Garacci Z, Kumar VCS, Thyarala SR, Hillard CJ, Venkatesan T. Hot-Water Bathing Improves Symptoms in Patients with Cyclic Vomiting Syndrome and Is Modulated by Chronic Cannabis Use.Digestive Diseases and Sciences · 2021 · 66(4):1153-1161doi:10.1007/s10620-020-06343-x · PMID 32472256

    Cross-sectional study of 111 cyclic vomiting patients: 73% bathed in hot water during episodes and over 80% of them noted marked relief; regular cannabis users chose 'very hot' water more often (50% versus 16%) and took longer to obtain relief. Lists proposed mechanisms (core temperature via CB1, skin TRPV1, blood shifted from gut to skin). Shows the sign is not specific to cannabis.

86. 86
    Huang J, Rayasam S, Graham C, Jones S. Topical Capsaicin for Symptomatic Treatment of Cannabinoid Hyperemesis Syndrome in a Pregnant Patient: A Case Report.Pain Medicine Case Reports · 2025 · 9(6):311-313PMID 41135021

    A 34-year-old at 11 weeks' gestation whose pain and nausea improved with topical capsaicin after multimodal treatment failed; states the hypothesis that cannabinoid use downregulates TRPV1. One case; no DOI listed in PubMed.

87. 87
    Won KJ, Celmins L. Managing cannabinoid hyperemesis syndrome in adult patients in the emergency department.American Journal of Health-System Pharmacy · 2025 · 82(24):1340-1352doi:10.1093/ajhp/zxaf125 · PMID 40458910

    Pharmacist review: data on drug treatment are scarce; cessation is the accepted cure; haloperidol, droperidol, ondansetron, metoclopramide and capsaicin are used; opioids and benzodiazepines should not be first-line. A review.

88. 88
    Levinthal DJ, Killian B, Issenman RM. Acute care of cyclic vomiting syndrome and cannabinoid hyperemesis syndrome in the home and emergency department.Neurogastroenterology and Motility · 2025 · 37(3):e14901doi:10.1111/nmo.14901 · PMID 39155452

    Review of abortive treatment at home and in the emergency department, including hot water and capsaicin; urges nonjudgmental, informed, compassionate care and individual emergency care plans; says research must still show whether CHS needs a different acute approach from cyclic vomiting. Includes a patient-association author.

89. 89
    Hickey JL, Witsil JC, Mycyk MB. Haloperidol for treatment of cannabinoid hyperemesis syndrome.American Journal of Emergency Medicine · 2013 · 31(6):1003.e5-6doi:10.1016/j.ajem.2013.02.021 · PMID 23583118

    Single case of marked improvement with haloperidol in an emergency department: the anecdote that preceded the trial.

90. 90
    Sabbineni M, Scott W, Punia K, Manuja K, Singh A, Campbell K, MacKillop J, Balodis I. SAEM GRACE: Dopamine antagonists and topical capsaicin for cannabis hyperemesis syndrome in the emergency department: A systematic review of direct evidence.Academic Emergency Medicine · 2024 · 31(5):493-503doi:10.1111/acem.14770 · PMID 37391387

    Evidence review for the 2024 GRACE-4 guideline (Guidelines for Reasonable and Appropriate Care in the Emergency Department): seven studies (five observational, two randomized), 492 patients; capsaicin (five studies, 386 patients) mixed, dopamine antagonists (two studies, 106 patients) beneficial; limited, small, unstandardized and at risk of bias.

91. 91
    Merino S, Tordera L, Jun A, Yang S. Mitigating the Risk of QTc Prolongation When Using Haloperidol for Acute Treatment of Cannabinoid Hyperemesis Syndrome in Adolescents and Young Adults.Journal of Clinical Medicine · 2025 · 14(1):163doi:10.3390/jcm14010163 · PMID 39797246

    Two adolescent cases (QTc 528 ms with low potassium and magnesium on a haloperidol infusion; 476 ms) and five severe published cases of QTc prolongation or torsades de pointes; recommends electrocardiographic monitoring and alternatives when risk is high. Case-level evidence.

92. 92
    Lee C, Greene SL, Wong A. The utility of droperidol in the treatment of cannabinoid hyperemesis syndrome.Clinical Toxicology · 2019 · 57(9):773-777doi:10.1080/15563650.2018.1564324 · PMID 30729854

    Retrospective review in Melbourne, 2006-2016: 76 presentations met criteria, 37 given droperidol (usually 0.625 mg); median length of stay 6.7 versus 13.9 hours and half the use of other antiemetics. Not randomized; sicker or different patients may have received different drugs.

93. 93
    Kelly GS, Meeks G, McCoul B, Doshi VK, Moran TP. Droperidol is associated with reduced length of stay in the treatment of cannabinoid hyperemesis syndrome.Clinical Toxicology · 2025 · 63(8):550-555doi:10.1080/15563650.2025.2516128 · PMID 40511503

    Retrospective study, two Atlanta emergency departments, March to August 2024: 211 encounters in 158 patients, droperidol in 36.5% (median 1.25 mg); length of stay 409 versus 641 minutes (adjusted ratio 0.76), less total medication and less opioid; two mild adverse reactions. Association; the authors call for a randomized trial.

94. 94
    Chopra Q, Peyko V, Lee JA, Puhalla L, Gemmel DJ, Bolotin T. Droperidol Plus Diphenhydramine for Symptom Improvement in Suspected Cannabinoid Hyperemesis Syndrome: A Prospective Cohort Study.Open Access Emergency Medicine · 2024 · 16:267-273doi:10.2147/OAEM.S473627 · PMID 39619486

    Single-arm prospective study of 47 patients given droperidol with diphenhydramine: nausea and vomiting scores fell from 8.3 to 3.1 at 30 minutes and 1.4 at 120 minutes; 12.9% returned within seven days. No control group, so spontaneous improvement cannot be excluded.

95. 95
    Román F, Llorens P, Burillo-Putze G. [Topical capsaicin cream in the treatment for cannabinoid hyperemesis syndrome].Medicina Clínica (Barcelona) · 2016 · 147(11):517-518doi:10.1016/j.medcli.2016.09.003 · PMID 27751515

    Spanish-language case letter (indexed as a case report in a young woman), no abstract in PubMed. Cited only to show that topical capsaicin had been reported before the 2017 case series.

96. 96
    Wagner S, Hoppe J, Zuckerman M, Schwarz K, McLaughlin J. Efficacy and safety of topical capsaicin for cannabinoid hyperemesis syndrome in the emergency department.Clinical Toxicology · 2020 · 58(6):471-475doi:10.1080/15563650.2019.1660783 · PMID 31482758

    Retrospective cohort of 43 Colorado patients comparing visits with and without capsaicin: length of stay not significantly different (201 versus 179 minutes), fewer additional doses, less opioid (166.5 versus 69 mg oral morphine equivalents), no significant adverse events. Each patient's own visits compared; not randomized.

97. 97
    Kum V, Bell A, Fang W, VanWert E. Efficacy of topical capsaicin for cannabinoid hyperemesis syndrome in a pediatric and adult emergency department.American Journal of Emergency Medicine · 2021 · 49:343-351doi:10.1016/j.ajem.2021.06.049 · PMID 34242945

    Single-center retrospective cohort of 201 patients (25 younger than 21): 55% versus 21% needed no more than one rescue medication with capsaicin; time to discharge after the reference drug 3.72 versus 6.11 hours; no difference in total length of stay or medication count. A corrigendum was published in 2024 (American Journal of Emergency Medicine 79:233, PMID 38423935); no retraction.

98. 98
    Pourmand A, Esmailian G, Mazer-Amirshahi M, Lee-Park O, Tran QK. Topical capsaicin for the treatment of cannabinoid hyperemesis syndrome, a systematic review and meta-analysis.American Journal of Emergency Medicine · 2021 · 43:35-40doi:10.1016/j.ajem.2021.01.004 · PMID 33493995

    Seven studies, 106 patients, to October 2020; mean time to symptom resolution 325 minutes and emergency stay 379 minutes, each from two studies with very wide intervals. Pools mostly uncontrolled data and cannot establish efficacy; the authors call for randomized trials.

99. 99
    Ilyas M, Fernando A, Choriyev A, Adi M, Ashraf A. Successful Management of Refractory Cannabinoid Hyperemesis Syndrome With Topical Capsaicin: A Case Report With Proposed Mechanism of Action and Literature Review.Clinical Medicine Insights: Case Reports · 2026 · 19:11795476261470568doi:10.1177/11795476261470568 · PMID 42491286

    Single case: a 28-year-old using about 2 g a day for seven years, vomiting about 20 times a day, stopped retching within 10 minutes of 0.1% capsaicin cream on the abdomen after standard drugs failed. Anecdote.

100. 100
     Kelly CM, Attridge M, Katsogridakis YL, Mrozek L, Jackson K, Hoffmann JA. Implementation of a Standardized Management Algorithm for Cannabis Hyperemesis Syndrome in a Pediatric Emergency Department.Pediatric Emergency Care · 2026 · 42(7):535-543doi:10.1097/PEC.0000000000003588 · PMID 42003265

     Before-and-after study in a Chicago pediatric emergency department, 128 encounters in 44 patients: after an algorithm, capsaicin use rose from 2.7% to 22.2% and metoclopramide from 6.8% to 42.6%, but admission (adjusted odds ratio 0.57, 95% confidence interval 0.17 to 1.86) and length of stay did not change.

101. 101
     Richards JR, Gordon BK, Danielson AR, Moulin AK. Pharmacologic Treatment of Cannabinoid Hyperemesis Syndrome: A Systematic Review.Pharmacotherapy · 2017 · 37(6):725-734doi:10.1002/phar.1931 · PMID 28370228

     Sixty-three articles, 205 patients, to February 2017: 4 prospective, 3 retrospective, 12 case series and 44 case reports. Benzodiazepines, then haloperidol and capsaicin, were most often reported effective acutely and tricyclic antidepressants for the long term; hot showers were reported effective in every case series and report. High-quality evidence was limited.

102. 102
     Hsu J, Kashyap S, Hurd C, McCormack L, Herrmann Z, Schwartz AC, Jackson J, DeMoss D. Treatment of cannabinoid hyperemesis syndrome: A systematic review and treatment algorithm for consultation-liaison psychiatrists.General Hospital Psychiatry · 2025 · 97:185-191doi:10.1016/j.genhosppsych.2025.10.012 · PMID 41129865

     Systematic review to July 2021 of 34 articles describing 63 individual cases: capsaicin, antipsychotics and benzodiazepines were reported to work better than promethazine, ondansetron and metoclopramide. Built entirely on case reports, which the authors acknowledge.

103. 103
     Geraci E, Cake C, Mulieri KM, Fenn NE. Comparison of Antiemetics in the Management of Pediatric Cannabinoid Hyperemesis Syndrome.Journal of Pediatric Pharmacology and Therapeutics · 2023 · 28(3):222-227doi:10.5863/1551-6776-28.3.222 · PMID 37303765

     Retrospective pediatric review at Penn State: benzodiazepines, haloperidol and capsaicin appeared more effective than traditional antiemetics, with minimal adverse effects. Observational.

104. 104
     Brown JM, Wilsey MJ, Dhana L, Lonsdale H. Acute Treatment of Adolescent Cannabinoid Hyperemesis Syndrome With Haloperidol, Lorazepam, and/or Capsaicin: A Single Institution Case Series.Journal of Psychiatric Practice · 2023 · 29(5):354-358doi:10.1097/PRA.0000000000000732 · PMID 37678364

     Six adolescents: four given haloperidol 5 mg with lorazepam 2 mg intravenously and one haloperidol with 0.025% capsaicin had full acute relief; one given capsaicin alone improved partly. Six patients, no comparison.

105. 105
     Sigal A, Padilla G, Carroll T, Mautone SG. Cannabinoid Hyperemesis Syndrome in Adolescents: The Role of Aprepitant as a New Treatment Option for Rapid Symptom Relief.Journal of Adolescent Health · 2025 · 77(6):1223-1225doi:10.1016/j.jadohealth.2025.08.004 · PMID 40965394

     Two adolescents who failed 36 to 45 hours of standard therapy stopped vomiting within an hour of aprepitant. Two cases.

106. 106
     Moore MD, Alzghari SK, Soliman AN. Cannabinoid Hyperemesis Syndrome Treated With Fosaprepitant: A Case Report.Cureus · 2025 · 17(8):e90477doi:10.7759/cureus.90477 · PMID 40979004

     Single case of intractable vomiting treated with intravenous fosaprepitant after other drugs failed.

107. 107
     Gawel RJ, Ho E, Gottlieb M, Kramer JA, Shalaby M. Management of cannabinoid hyperemesis syndrome with an erector spinae plane block in the emergency department.American Journal of Emergency Medicine · 2025 · 100:93-95doi:10.1016/j.ajem.2025.11.023 · PMID 41313935

     Single refractory case with complete relief after an ultrasound-guided nerve block beside the thoracic spine, avoiding admission. One case.

108. 108
     Rehman A, Javed MA. Inhaled Isopropyl Alcohol for Refractory Cannabis Hyperemesis Syndrome: A Case With Pneumomediastinum and Pneumothorax.Cureus · 2025 · 17(9):e93493doi:10.7759/cureus.93493 · PMID 41170261

     A 26-year-old daily user with pneumothorax and pneumomediastinum from retching; nausea responded to sniffed isopropyl alcohol swabs. One case.

109. 109
     Khamis A, Dygulski S. Low-dose metoclopramide-induced dystonia in cannabis withdrawal syndrome manifesting as intractable nausea and vomiting.BMJ Case Reports · 2025 · 18(5):e264815doi:10.1136/bcr-2025-264815 · PMID 40379294

     A young woman with repeated admissions for vomiting tied to heavy cannabis use presented with intractable nausea, vomiting and frequent hot bathing five days after her last use, framed as cannabis withdrawal syndrome, which the authors say begins within a week of stopping; she developed dystonia after low-dose metoclopramide. One case.

110. 110
     Turcotte AM, Lemieux-Bourque C, McCarey C, Lévesque K, Kerkerian G, Labrecque AA. Gabapentin for the Management of Suspected Cannabis Withdrawal in a Pregnant Patient With a History of Cannabinoid Hyperemesis Syndrome: A Case Report.Case Reports in Obstetrics and Gynecology · 2026 · 2026:3043344doi:10.1155/crog/3043344 · PMID 42683213

     A 24-year-old at 20 weeks' gestation with cannabis use disorder, a prior CHS admission and recently reduced cannabis use had recurrent vomiting and labile hypertension; suspected withdrawal was treated with off-label gabapentin, with resolution of symptoms and blood pressure within 24 hours. One case.

111. 111
     Hicks BM, Price AM, Whittington BJ, Goldman P, Ilgen MA. Links between cannabinoid hyperemesis syndrome symptoms and drug use, mental health problems, antisocial behavior, and personality in a national survey of adults in the United States.Drug and Alcohol Dependence · 2026 · 287:113323doi:10.1016/j.drugalcdep.2026.113323 · PMID 42617216

     Same 2025 national survey: people with CHS symptoms reported more other drug use and overdoses, depression, anxiety, sleep problems, chronic pain and disinhibited traits than daily users without symptoms (mean effect size d = 0.58). Cross-sectional associations.

112. 112
     Hicks BM, Whittington BJ, Price AM, Goldman P, Ilgen MA. Elevated suicidal thoughts and behaviors, proximal suicide risk factors, and non-suicidal self-injury among adults reporting symptoms of Cannabinoid Hyperemesis Syndrome: Results from a national survey of US adults.medRxiv (preprint) · 2026 · posted 13 June 2026doi:10.64898/2026.02.26.26347185 · PMID 42326769

     Preprint, not peer reviewed: 191 daily users with CHS symptoms reported the highest lifetime and past-year suicidal thoughts and behaviors of any group, higher than daily users without symptoms. Cross-sectional; cannot separate cause from comorbidity.

113. 113
     Dean L, Padley MA, Pham HT, Finedore M, Vu A, Sargent JA, Skovira C, Kolacki C, Ouellette L, Judge BS, Riley BD, Jones JS. Assessing the Quality of YouTube Videos About Cannabinoid Hyperemesis Syndrome.Cureus · 2026 · 18(5):e109113doi:10.7759/cureus.109113 · PMID 42317926

     Cross-sectional review of 97 videos (795,264 cumulative views): 25.8% useful, 2.1% exemplary, 52.6% not useful and 19.6% misleading; several of the most-viewed contained substantial misinformation; views did not track quality.

114. 114
     Bonnet U. Cannabis Hyperemesis Syndrome Recovers Completely When the Use of Cannabis or Synthetic Cannabinoids Is Permanently Discontinued-Cyclic Vomiting Syndrome Does Not.Gastroenterology · 2024 · 167(5):1054-1055doi:10.1053/j.gastro.2024.06.025 · PMID 38945497

     Letter, no abstract in PubMed: its title states the two-condition position, including synthetic cannabinoids as a cause. Cited only for the position taken.

115. 115
     Felix-Tellez FA, Morel-Cerda EC, Jiménez-Castillo RA, Valdovinos-García LR, Gómez-Escudero O, Valdovinos-Díaz MÁ, Coss-Adame E, Velasco JAV, Monjaraz EMT, Montijo-Barrios E, Solís-Ortega AA, Frazier RJ, Venkatesan T, Remes-Troche JM. Clinical Characteristics and Associated Factors in Mexican Patients With Cyclic Vomiting Syndrome and Cannabinoid Hyperemesis Syndrome.Journal of Neurogastroenterology and Motility · 2025 · 31(3):330-339doi:10.5056/jnm24182 · PMID 40625249

     Cross-sectional study at five Mexican centers, Rome IV criteria: 30 cyclic vomiting and 16 CHS patients. CHS patients were older (median 27 versus 23 years), smoked tobacco (50.0% versus 26.7%) and used alcohol riskily (31.3% versus 0%) more often, and were diagnosed sooner (26.5 versus 35.4 months); 13.3% of cyclic vomiting patients used cannabis; admissions and length of stay did not differ. Small; no follow-up.

116. 116
     Sinan K, Beydoun S, Lulgjuraj T. The Clinical Conundrum of Cyclic Vomiting in the Cannabinoid User: Simply Cannabinoid Hyperemesis or Could It Be More?ACG Case Reports Journal · 2025 · 12(5):e01711doi:10.14309/crj.0000000000001711 · PMID 40401049

     Two adolescents with cyclical vomiting and cannabis use whose episodes were tied to the menstrual cycle (catamenial cyclic vomiting syndrome) and resolved on hormonal contraception despite continued cannabis use. Two cases.

117. 117
     Mantelli G, Fiore A, Barberi C, Zaia B, Ricci G, Carollo M, Malalan F. Severe Presentation of Cannabinoid Hyperemesis Syndrome With Mixed Acid-Base Disorder and Cardiac Complications: A Case Report.Case Reports in Medicine · 2025 · 2025:8161294doi:10.1155/carm/8161294 · PMID 40438465

     A 28-year-old with severe hypokalemia, signs of hypocalcemia and QTc prolongation; QT-prolonging antiemetics were avoided and midazolam used instead. One case.

118. 118
     Elbaghdady A, Ahmed A, Elmahdy A. Cannabinoid Hyperemesis Syndrome: A Rare Cause of Severe Abdominal Pain and Hyperlactataemia.Cureus · 2025 · 17(9):e92444doi:10.7759/cureus.92444 · PMID 41111845

     British case with lactate of 6.1 mmol/L attributed to dehydration and stress; treated with fluids, haloperidol and capsaicin. One case.

119. 119
     Patel DK, Lippert WC. Atypical Presentation of Spontaneous Pneumomediastinum Secondary to Cannabinoid Hyperemesis Syndrome.Cureus · 2025 · 17(10):e95097doi:10.7759/cureus.95097 · PMID 41281024

     A 20-year-old with pneumomediastinum, lung lacerations and a small pneumothorax but no chest pain; full recovery. Case report.

120. 120
     Argamany JR, Reveles KR, Duhon B. Synthetic cannabinoid hyperemesis resulting in rhabdomyolysis and acute renal failure.American Journal of Emergency Medicine · 2016 · 34(4):765.e1-2doi:10.1016/j.ajem.2015.08.051 · PMID 26422191

     First reported case of hyperemesis from synthetic cannabinoids leading to muscle breakdown and acute renal failure. One case; shows the syndrome is not confined to plant cannabis.

121. 121
     Alaniz VI, Liss J, Metz TD, Stickrath E. Cannabinoid hyperemesis syndrome: a cause of refractory nausea and vomiting in pregnancy.Obstetrics and Gynecology · 2015 · 125(6):1484-1486doi:10.1097/AOG.0000000000000595 · PMID 25774930

     A pregnant 28-year-old with multiple admissions for episodic vomiting complicated by Mallory-Weiss esophageal tears and dehydration, who showered compulsively; diagnosed after extensive workup. One case.

122. 122
     Ali K, Masood Shah A, Hyder A, Balderas V. Triple Air Leak Syndrome in Cannabinoid Hyperemesis: A Diagnostic Challenge Managed Conservatively.ACG Case Reports Journal · 2025 · 12(10):e01858doi:10.14309/crj.0000000000001858 · PMID 41112854

     A 21-year-old woman with CHS developed pneumomediastinum, pneumopericardium and pneumoretroperitoneum; esophageal rupture (Boerhaave syndrome) was suspected and excluded by imaging; full recovery with conservative care. One case.

123. 123
     Haque OI, Kiyani M, Hussain S. Cannabis-Related Takotsubo Cardiomyopathy Presenting With Ventricular Tachycardia and Cardiogenic Shock Successfully Treated With Milrinone and Intra-Aortic Balloon Pump.JACC Case Reports · 2025 · 30(20):104246doi:10.1016/j.jaccas.2025.104246 · PMID 40392660

     A 63-year-old woman with multiple prior CHS admissions presented with intractable vomiting after cannabis use, potassium 2.6 mmol/L, lactate 7.1 mmol/L, a wide-complex tachycardia needing cardioversion and cardiogenic shock; normal coronary arteries; ejection fraction 15% to 20%, recovering to baseline after four weeks of support. One case.

124. 124
     Kattamuri L, Senapati SG, Popuri H, Fernandez L, Sharma K, Sirineni S, Duvvuru SR, Vulisha A. Wernicke's Encephalopathy Secondary to Cannabis Hyperemesis Syndrome.Journal of Brown Hospital Medicine · 2026 · 5(1):151455doi:10.56305/001c.151455 · PMID 41488447

     A woman in her twenties after eight weeks of vomiting and more than 10 kg of weight loss: eye-movement palsy, nystagmus, ataxia, thalamic MRI changes; rapid recovery with intravenous thiamine. One case.

125. 125
     Hanley S, Imcha M, Mohamad MM. Cannabinoid hyperemesis syndrome in pregnancy: a case series and review.Obstetric Medicine · 2025 · 18(4):264-271 (published online 24 December 2024)doi:10.1177/1753495X241307415 · PMID 39759763

     Two Irish cases resolved with cessation (one infant born at 2180 g needing five days of neonatal intensive care); notes only 11 earlier published cases of CHS in pregnancy and likely under-reporting. Case series.

126. 126
     Myran DT, Roberts R, Pugliese M, Corsi D, Walker M, El-Chaâr D, Tanuseputro P, Simpson A. Acute care related to cannabis use during pregnancy after the legalization of nonmedical cannabis in Ontario.CMAJ · 2023 · 195(20):E699-E708doi:10.1503/cmaj.230045 · PMID 37220929

     Ontario population data: acute care for cannabis use in pregnancy rose from 11.0 to 20.0 per 100,000 pregnancies after legalization; such pregnancies had more acute care for hyperemesis gravidarum (30.9% versus 2.5%), preterm birth and neonatal intensive care. Association; does not identify CHS specifically.

127. 127
     Ballaman J, Reiff C, Voirol U. [Management of cannabinoid hyperemesis syndrome].Revue Médicale Suisse · 2026 · 22(956):632-634doi:10.53738/REVMED.2026.22.956.47892 · PMID 41923507

     French-language review with a case; its English abstract states that CHS 'affects approximately one-third of cannabis users'. Cited as an example of a figure that outruns its source, which was a convenience sample of near-daily smokers.

128. 128
     Lefebvre E, Simons L, Duval M, Laforgue EJ, Victorri-Vigneau C. Cannabinoid Hyperemesis Syndrome Presumed Secondary to CBD Use: A Case Report.Journal of Addiction Medicine · 2025 · 19(1):115-117 (published online 2 September 2024)doi:10.1097/ADM.0000000000001378 · PMID 39221821

     French addictovigilance case: a 32-year-old man who switched from cannabis to daily cannabidiol had recurrent vomiting and abdominal pain, eased by hot showers, for six months without cannabis. The authors list THC stored in fat, conversion of cannabidiol to THC on burning, and a direct cannabidiol action on TRPV1 as possible explanations and call the link uncertain. One case; the product was not analyzed in the abstract.

129. 129
     Bradlow R, Sorensen J, Cunningham A, Daugherty S, Hadinata E, Armstrong F, Jamshidi N. Potential Iatrogenic Harms From Medicinal Cannabis Prescribing in Australia: A Case Series.Drug and Alcohol Review · 2026 · 45(6):e70255doi:10.1111/dar.70255 · PMID 42675819

     Three men aged 20 to 24 with psychiatric disorders and substance use vulnerabilities who were prescribed medicinal cannabis; the harms described include cannabinoid hyperemesis syndrome, cannabis use disorder, paranoia and delayed treatment, and prescribing continued in two despite harm. Three cases.

130. 130
     Ralston MJ, Osman A. Evaluating Delta-8-THC-Induced Psychosis: A Systematic Review.Clinical Neuropharmacology · 2025 · 48(1):20-23doi:10.1097/WNF.0000000000000619 · PMID 39805119

     Systematic review of delta-8-THC case reports: six reports describing nine patients, most of them men in their twenties; reported effects included psychosis, mood lability and cannabinoid hyperemesis syndrome. Case reports only.