Iodine in the specimen

In brief

The idea, and where iodine actually touches tissue

The iodine hypothesis, stated as plainly as it can be, runs like this: iodine applied during surgery or while tissue is being handled kills parasites, a dead parasite goes unrecognized, and so cancers that parasites caused are recorded as cancers of unknown cause. It deserves a fair hearing, because two of its premises are true. Iodine does reach tissue around the time a cancer is diagnosed ^1,21, and at some doses it does kill parasites ^30,31. What the hypothesis needs, and what the record does not supply, is a third step: that a parasite killed by iodine vanishes from a slide made from fixed tissue. This page takes the steps one at a time, and gives the strength of the evidence for each.

The first route is the skin. Before an incision the skin is painted with an antiseptic, a chemical that kills microbes on living tissue, and for decades the standard was povidone-iodine, iodine held in a complex with the polymer povidone and used in 10% and 7.5% solutions ^2,24, applied as a scrub followed by a paint ¹. Its target is the skin at the incision ¹. In a 2010 trial of 849 patients, chlorhexidine in alcohol prevented more wound infections than a povidone-iodine scrub and paint ¹. In 2024 povidone-iodine in alcohol proved noninferior, meaning not meaningfully worse, in 3,360 Swiss cardiac and abdominal surgery patients ²⁰, and a related iodine-in-alcohol preparation, iodine povacrylex, led to fewer infections than chlorhexidine after surgery for closed fractures in 6,785 patients in the United States and Canada, 2.4% against 3.3%, a borderline result (P = 0.049, just inside the usual threshold for chance) that did not appear in 1,700 open fractures ³.

The second route puts iodine directly on tissue that is about to become a specimen. Lugol's iodine, a strong brown iodine solution named for the physician Jean Guillaume Lugol, who prescribed it to disinfect the vagina ⁶, is sprayed onto the lining of the esophagus during endoscopy, an examination with a camera on a flexible tube; trials have used 10 mL of a 2% solution ^4,21. It is also applied to the cervix during colposcopy, a magnified examination of the cervix, and in naked-eye screening programs ^6,7. Healthy squamous lining, the flat-celled surface of both organs, holds glycogen, a stored sugar that iodine colors greenish-brown; carcinoma and severe dysplasia, meaning markedly abnormal precancerous change, stay pale and are biopsied ^8,9. Surgeons have also bathed a freshly removed esophagus in 1% Lugol's for two to three minutes to see where a cancer ends ⁸. A third route puts iodine straight onto cancer on purpose. In colorectal surgery the bowel below or around the tumor is washed out before the join is made, to kill cancer cells shed into the lumen, the bowel's inner channel: in 1984, 48 of 72 surgeons surveyed in southwest England used such a washout, for about two minutes on average, and povidone-iodine at 5% to 100% was rapidly lethal to freshly harvested colorectal cancer cells ³²; a 2002 Belgian study irrigated the whole colon of 14 patients with 5% povidone-iodine plus 12% Gastrografin, an iodinated contrast agent, just before surgery, the solution reaching the cecum in two minutes, and saw superficial shedding of the surface lining that had healed within a week ²³; a 2006 Turkish series used a 5% povidone-iodine rectal washout in 38 of 96 patients, with no difference in local recurrence or in malignant cells found on the stapler ³³; and in 2021, 2% povidone-iodine lavage killed tumor cells shed during the endoscopic removal of colorectal lesions ³⁴. The bowel then went to pathology as it always does; the one measured tissue effect was that shedding of the lining, and none of these studies looked for any effect on the diagnosis itself ^23,33.

The fourth route runs the other way. In the stool laboratory Lugol's iodine is a stain, mixed with a little stool on a slide so that cysts, the dormant walled stage of single-celled parasites, can be seen and named ^10,11. An iodine-containing stain and preservative called MIF, after its ingredients merthiolate, iodine and formaldehyde, was published in 1953 for identifying intestinal protozoa ^35,36. The fifth route is research imaging: iodine stains make soft tissue visible to micro-CT, a high-resolution X-ray scanner, in specimens that are already preserved ²², sometimes after minerals have been dissolved out of tooth or bone, a step called decalcification ³⁷. A sixth use is on the slide itself. Tissue fixed in B-5, a mercury-containing fixative, is treated with Lugol's iodine and then 5% sodium thiosulfate to dissolve the mercury deposits before antibody staining ^17,38. That step is the one documented case found for this page of iodine changing what a fixed slide shows: in a 2003 test of 75 antibodies run with and without the clearing, it abolished staining for three (CD5, CD30 and synaptophysin, antibody markers used to classify lymphomas and hormone-producing tumors) and weakened three more (ALK, Ulex and GFAP) ¹⁷, and a 2000 letter was titled 'Omit iodine and CD30 will shine' ³⁸. What it alters is antibody staining; neither report looked at shape or DNA. B-5 itself was the subject of a 2005 search for a mercury-free replacement because of costly disposal ³⁹.

The history: a revealer first, a killer second

Iodine entered pathology as something that reveals. Chemists found in 1814 that iodine colors starch, and in 1853 Rudolf Virchow applied an iodine reaction to a waxy spleen, the first histochemical test, meaning a chemical color reaction on tissue, for the deposits later called amyloid ⁴². Lugol's solution reached the cervix through Walter Schiller, who tried nearly 200 dyes and settled on it, and in 1928 W. Lahm reported that glycogen falls as cells grow more abnormal, the principle behind iodine tests of the cervix and, later, the esophagus ^6,8. The stool laboratory took up iodine for the same purpose, to identify intestinal protozoa ³⁵, and still uses it that way ¹⁰, although by 1983 a head-to-head comparison had found its wet mounts less accurate for Giardia cysts than a permanent stain ⁴⁵.

Iodine's record as a killer of parasites is shorter and less steady, and it has reversed more than once. Water-treatment chemicals were shown in 1989 to need hours rather than minutes against Giardia cysts ¹², and iodine tablets in 1997 to inactivate only 10% of Cryptosporidium oocysts, its hardy egg-like stage, in the recommended 20 minutes ²⁷. Povidone-iodine left roundworm eggs viable in a 2012 test ¹³ but stopped them developing in a 2024 one ¹⁴. Povidone-iodine was a poor amoebicide in a 2000 test of 19 Australian corneal isolates ⁴⁶ and one of the best in a 2014 test of 56 Japanese isolates ³⁰, and in 2026 a randomized trial found that adding it to standard treatment did not clear the amoeba from the eye faster ²⁸. In the operating room a 2010 trial favored chlorhexidine ¹; by 2024 two large trials had brought iodine back ^3,20, and at one United States trauma center iodine povacrylex went from 0.8% of fracture operations to 86% after the newer results were publicized ⁴⁷, though pooled analyses in 2025 and 2026 still gave chlorhexidine a small edge for superficial wound infections ^48,49.

Through all of it, no indexed paper found for this page has argued that iodine erases parasites from cancer specimens. The most recent review of parasitic lesions that imitate tumors names rarity and morphological pitfalls, not reagents, as the reasons pathologists struggle with them ²⁶. The record of iodine as a parasite killer comes mostly from water treatment, contact lenses, eye infections and surgery for hydatid cysts, the fluid-filled larval cysts of the Echinococcus tapeworm, fields whose tests ask whether organisms are still alive rather than what a fixed tissue section shows ^27,28,31. The timeline below marks each belief that was later overturned as a reversal.

What iodine does to cysts, eggs and larvae, at the doses that touch tissue

Disinfection depends on concentration multiplied by contact time, and every wall around an organism lengthens the time it needs ^12,41. Bacteria are the easy case: in a 2011 laboratory experiment, 0.4% povidone-iodine killed 99.9% of three bacterial isolates and a yeast within 15 seconds ⁵⁴. In the same experiment it did not inhibit the cysts of Acanthamoeba, a free-living amoeba that infects the eyes of contact-lens wearers ⁵⁴. Strength is not simply better: in 1982 Staphylococcus aureus survived two minutes in full-strength 10% povidone-iodine but not 15 seconds in a 1:100 dilution ⁴⁰, and povidone-iodine keeps most of its iodine bound to the polymer, so little is free at any moment ²⁴. Every result in this section is in vitro, meaning in glassware rather than in a body, unless it says otherwise.

Giardia and Cryptosporidium, two intestinal protozoa, pass in stool as walled cysts and oocysts, the oocyst being the hardy, egg-like stage of Cryptosporidium ²⁷. In 1989 none of seven chemical water treatments inactivated 99.9% of Giardia cysts in 30 minutes at 10 °C, though every iodine product did so after eight hours ¹². In 1997 iodine tablets at 13 to 18 mg per liter for 20 minutes achieved a 3-log reduction, a thousandfold fall, of Giardia in ordinary water but inactivated only about 35% of cysts in acidic worst-case water; Cryptosporidium was harder still, with 10% inactivated at 20 minutes and 66% to 81% after 240 minutes ²⁷.

Against Acanthamoeba cysts the record is genuinely contested. Povidone-iodine had poor activity against 19 corneal isolates in 2000 ⁴⁶; in 2014, 1% povidone-iodine was second only to the drug natamycin against cysts from 56 patients after 1 or 24 hours of exposure ³⁰; and in 2022 it was the only one of eight drugs that completely stopped challenged cysts producing trophozoites, the active feeding stage, in all four isolates and five replicates ⁵⁵. A 2023 Dutch test found cysts resistant to all 16 contact-lens solutions, including one based on povidone-iodine ⁵⁶. A 2024 Spanish test that detected surviving amoebae by their RNA found a povidone-iodine lens system alone left 38% of soft hydrogel and 12% of silicone-hydrogel lenses positive, but cleared every lens when a cleaner was used first ⁵⁷, and a 2026 systematic review of ten studies ranked the oxidative systems, hydrogen peroxide and povidone-iodine, above the multipurpose solutions, while warning that the industry test standard does not include Acanthamoeba at all ⁵⁸. The 2019 study that warned about anesthetic drops also measured povidone-iodine and placed it below the biguanides, the drugs used to treat the infection, but above the diamidines, another treatment class ¹⁵. At its minimum cysticidal concentration, 0.04%, povidone-iodine shrank cysts and tore their walls apart under the electron microscope ⁵⁹, the strongest laboratory evidence that iodine can destroy a parasite's structure. A company-authored 2025 study found 0.05% povidone-iodine stopped trophozoites moving within two minutes ⁶⁰.

Worm eggs are another order of toughness ¹³. Povidone-iodine at 1%, 10%, 50% and full strength had no effect on unembryonated eggs, ones that have not yet begun to develop, of Ascaris suum, a pig roundworm, at any exposure from 5 to 120 minutes, while 5% phenol inactivated them completely ¹³. The protection is structural: the Ascaris eggshell is 3 to 4 micrometers thick, and stripping its outer layers made eggs far more vulnerable to ultraviolet light ⁴¹. That result did not stand unchallenged. In 2024 a Chinese laboratory exposed Ascaris suum eggs to eight disinfectants and then incubated them for 15 days: 5% and 10% povidone-iodine for 30 to 120 minutes, and 1% to 10% for 15 days, completely stopped the eggs developing to the second larval stage ¹⁴. The two studies measured different things, immediate viability in 2012 and later development in 2024, so the fair summary is that short contact with surgical-strength povidone-iodine may stop a roundworm egg maturing while leaving the egg itself in place, since the 2024 study counted the eggs it had treated. The exception is the larval tapeworm inside a hydatid cyst, the fluid-filled cyst of Echinococcus: 10% povidone-iodine killed 100% of protoscoleces, the larval heads, from sheep livers within one minute ³¹. Surgeons use such scolicidal agents, chemicals that kill protoscoleces, before and during cyst operations ³¹, and the hydatid cyst is recognized in pathology by its wall and parasitic lining ²⁶. A 2023 Turkish comparison found undiluted 10% povidone-iodine scolicidal at every time tested, alongside a new hypochlorous acid preparation ⁶¹.

Why viability does not matter to a fixed specimen

Every test for an organism asks one of three questions: is it alive, what shape is it, or whose DNA is this? Culture, growing the organism in the laboratory, asks the first and fails if the organism has died ¹⁵. That is the one place antiseptics are documented to cause false negatives ¹⁵. A 2019 laboratory study warned eye doctors that some anesthetic drops, and drops preserved with benzalkonium chloride, may harm Acanthamoeba if applied before a sample is taken, producing false-negative tests ¹⁵. Culture struggles even without that: in a London eye hospital series of 259 corneal infections, measured against cases positive on any of the three tests, culture found 35.6% of Acanthamoeba keratitis, confocal microscopy, which reads the organism's shape in the living cornea, found 77.1%, and PCR, the polymerase chain reaction, which copies and detects DNA, found 63.3% (culture was available for 203 patients and confocal microscopy for 149) ¹⁶.

A cancer specimen is asked the other two questions. Fixation, the step that follows removal, is meant to harden tissue and prevent decomposition and autolysis, the cells' digestion of themselves; the routine fixative is 10% formalin, which is about 4% formaldehyde in water ^18,62. A fixed specimen is dead by design, any parasite included; so, as far as shape and DNA go, iodine killing a parasite earlier takes away nothing that histology, the microscopic study of thin tissue sections, depends on. That is an inference from how fixation works ¹⁸, not a measured result, and it has one documented exception that concerns antibody staining rather than shape: the iodine step used to clear mercury from B-5-fixed slides can abolish some immunostains ¹⁷. Shape is what matters, and shape survives: schistosome eggs embedded in the bladder wall were reported in the same biopsy that showed a bladder cancer ⁶³, and fragments of a filarial worm, a thread-like roundworm, in a resected lung nodule were described from the cuticle, the worm's outer skin, and the muscle and internal ridges seen in fixed tissue ⁶⁴.

DNA survives fixation too ¹⁹. PCR on paraffin blocks detected Leishmania in 24 of 29 skin biopsies that microscopy had called negative, for 92% sensitivity and 100% specificity ¹⁹; in the lung nodule above, DNA from the block settled a species question that the cuticle could not ⁶⁴; and in 2015 a tumor of tapeworm cells that were unrecognizable as tapeworm tissue was identified by PCR aimed at all eukaryotes, the organisms whose cells have nuclei ⁶⁵. The limit is age, not iodine: Echinococcus DNA was found in all six blocks kept under six years, and the authors advise blocks under five ⁶⁶. Eye specialists are now developing viability PCR, a version designed to tell live organisms from dead ones ⁶⁷.

The nearest thing to a direct test of iodine and histology is not about parasites. When 24 resected esophagi were stained with Lugol's and then examined under the microscope, the unstained zones were mostly invasive carcinoma, carcinoma in situ, meaning cancer still confined to the surface layer, or severe dysplasia, and stain intensity tracked the thickness of the glycogen-containing layer ⁹: iodine marked the tissue and histology read it. The nearest direct test on molecules is from the cervix: in 2005, adjacent pieces of six hysterectomy specimens were frozen untouched, after acetic acid, or after acetic acid and Lugol's iodine, and across 4,850 detectable gene probes no gene was differentially expressed, so the authors concluded that the standard pre-biopsy applications do not substantially change gene-expression patterns in the normal cervix ⁶⁸. There are honest counterweights. Strong iodine stains shrink soft tissue ²⁹; a 5% povidone-iodine bowel lavage stripped the superficial lining within minutes, though it regrew within a week ²³; the iodine clearing step on mercury-fixed slides killed three antibody stains ¹⁷; Lugol's, used to preserve plankton, often lost the flagella and other fine structures of fragile single-celled algae ⁶⁹; and one iodinated contrast agent interfered with later immunohistochemistry, staining with antibodies, in fixed rabbit cartilage, while hematoxylin and eosin, the standard pink-and-purple stain, still worked ⁷⁰. None of these tested a parasite in human tissue.

How iodine's effects, and parasites, are measured

Each kind of evidence on this page measures something different. Kill studies measure viability: whether cysts later produce active amoebae on agar plates, watched for 7 days ^30,55; whether larval tapeworm heads take up eosin dye, the test used for protoscoleces ³¹; or how many organisms survive, expressed as log reduction ²⁷. None of these measures whether an organism can still be recognized. Iodine's staining is measured too. Resected esophagi have been graded from hyperstaining to unstained, grades I to IV ⁹, and the number of Lugol-voiding lesions, patches that refuse the stain, predicts later cancers: among 331 patients treated for early esophageal cancer, new esophageal cancers appeared within two years in 4% with none, 9.4% with one to nine, and 24.7% with ten or more ⁴⁴.

Finding a parasite in a specimen is measured against a reference, and every reference has blind spots. In 228 Tanzanian women, eggs of Schistosoma haematobium, one of three parasites classed as definite human carcinogens ⁷¹, were found in the cervix in 49% by direct examination of compressed biopsy tissue, 18% by routine histologic sections and 3% by cervical smears, and sections did better when eggs were dense ²⁵. Stool microscopy with Lugol's iodine found Giardia in 31% of 97 Egyptian samples where PCR found 42.3%, the extra cases behaving like low-burden infections ¹¹. In 90 Turkish patients called Entamoeba histolytica by saline and Lugol's mounts, two antigen tests failed to confirm 62.2% and 64.4%, because microscopy cannot tell it from its look-alike Entamoeba dispar ⁴³.

• Lugol's iodine stool mountA drop of stool mixed with Lugol's iodine and examined under the microscope, a routine arm of stool parasitology ^10,11.Routine ova-and-parasite microscopy ¹⁰Found Giardia in 31% of 97 Egyptian samples where PCR found 42.3% ¹¹Light infections below the microscope's limit; less accurate for Giardia cysts than a permanent trichrome stain in 1983 ⁴⁵; cannot tell Entamoeba histolytica from E. dispar ^11,43
• Lugol's chromoendoscopy and visual inspection with Lugol's iodineChromoendoscopy means endoscopy with a dye: Lugol's is sprayed on the esophagus or painted on the cervix, and patches that do not stain are biopsied ^7,50.Screening high-risk esophagus and, in low-resource programs, the cervix ^7,44Esophagus 92% sensitivity and 82% specificity per patient across 1,911 patients; cervix 91.7% sensitivity for high-grade lesions in 56,939 women ^7,50Specificity is the weakness; narrow band imaging matched sensitivity and was more specific ⁵⁰, though in 2024 a dye-free camera missed 18.4% of cancers that Lugol's then found ⁵¹
• Culture of a corneal scrapingThe one test an antiseptic can genuinely blind, because it needs a live organism ¹⁵.Eye infections, including Acanthamoeba keratitis, infection of the cornea ¹⁶Found 35.6% of Acanthamoeba keratitis cases that any of three tests had found, in a London series of 259 corneal infections (culture available for 203) ¹⁶Organisms killed or impaired before sampling, including by some preserved drops ¹⁵
• PCR (DNA test) on the paraffin blockCopies and detects parasite DNA from fixed, embedded tissue, alive or not ^19,66; one Swiss center has since 2021 sequenced all the DNA in a block without choosing a target first, finding 9 parasites among 229 pathogens in 623 routine blocks ⁷².On request, when morphology is ambiguous ^26,6492% sensitivity and 100% specificity for cutaneous leishmaniasis, a parasitic skin infection ¹⁹Older blocks: all six Echinococcus blocks under six years old were positive, and blocks under five years are advised ⁶⁶
• Compressed biopsy for schistosome eggsDirect microscopic examination of a cervical biopsy, compared with routine sections and smears ²⁵.Research and endemic-area diagnosis of genital schistosomiasis ²⁵Eggs in 49% of 228 Tanzanian women, against 18% by routine histology and 3% by smear ²⁵Histology's yield falls when eggs are sparse ²⁵

What is done about iodine's real effects

Where iodine causes real harm, the remedies are mundane. Lugol's on the esophagus causes retrosternal discomfort, pain behind the breastbone, and spraying 5% sodium thiosulfate afterward, at a cost of $0.15 a use, relieved symptoms lasting beyond 30 minutes in a 2001 trial of 120 men ²¹; in 2019, 2% vitamin C, which can in theory neutralize free iodine, did as well in 240 patients ⁴. Lower strengths help: 0.6% Lugol's gave images as good as stronger solutions with less injury to the stomach lining ⁵. A dye-free option also exists. Narrow band imaging, an electronic light setting that brings out the surface relief and its blood vessels without dye, matched Lugol's sensitivity, 88% against 92% per patient, with better specificity, 88% against 82% ⁵⁰. It is not a complete substitute: in 2024, in 699 high-risk patients examined with blue-light imaging, a related dye-free setting, and then with Lugol's, the dye-free view missed 9 of 49 cancers that Lugol's caught ⁵¹.

In the operating room the choice between iodine and chlorhexidine now rests on trials of wound infection ^1,3,20. Their funding differs. The 2024 fracture trial was publicly funded, by the Patient-Centered Outcomes Research Institute and the Canadian Institutes of Health Research ³; the 2010 chlorhexidine trial's own disclosure, which its PubMed record does not reproduce, reports support from Cardinal Health, the maker of the chlorhexidine-alcohol preparation it tested ¹. None of these trials examined specimens; all counted wound infections ^1,3,20. After the fracture trial, one trauma center went from 0.8% to 86% iodine povacrylex use following a dissemination push in February 2024 built on surgeon and nursing education, posted reminders and supply-chain support, and held that level for 17 months ⁴⁷.

For diagnosis, the documented fixes address real problems rather than iodine. Eye doctors have been warned that some drops applied before sampling can spoil a culture ¹⁵. Pathologists facing a possible parasite are advised to send slides to an infectious-disease pathologist or a parasitologist and to add molecular testing ²⁶, preferably on blocks under five years old ⁶⁶, and where available untargeted sequencing of the block, which a Swiss pathology service ran on 623 fixed samples between 2021 and 2025 with usable results even from poor-quality tissue ⁷². For bone, decalcifying with EDTA, a chemical that gently binds calcium, or briefly with formic acid, rather than with hydrochloric acid, preserves antigens and DNA ⁷³, and a mercury-free fixative performs as well as the mercury fixative B-5 ³⁹. Laboratories still using B-5 are advised to run control tissue through the same iodine clearing step, so that a stain the step kills is caught ¹⁷.

What was believed and is not

Iodine sits in two literatures that rarely meet, disinfection and diagnosis, and beliefs travel between them without their conditions attached. A kill result from a dish becomes a claim about a patient, although the one randomized trial of povidone-iodine against an amoeba found no faster clearance ^28,30. A culture problem becomes a slide problem, although only culture needs the organism alive ¹⁶. The cards below set out each belief, what replaced it, and when.

Why parasites really go missing

If parasites are being missed in cancer specimens, the evidence points to sampling and recognition, not to reagents. Sampling first: a section is one thin slice through one small piece of tissue, and in the Tanzanian cervical study routine sections found eggs in 18% of women while direct examination of compressed biopsies found them in 49%, with sections succeeding mainly when eggs were dense ²⁵. Nobody has measured the same loss for other parasites scattered through tumors, but nothing suggests they behave better. The page on how cancer is tested follows that arithmetic step by step, from the operating room to the slide.

Recognition second. A 2025 review states that parasitic cysts and pseudocysts are rarely encountered by pathologists, carry many morphological pitfalls and can be misdiagnosed, and it recommends expert review and combined histological and molecular diagnosis ²⁶. In the 2015 tapeworm case the cells were unrecognizable as tapeworm tissue until PCR named them ⁶⁵, and in the 2026 lung case the worm's cuticle was unusual enough that its shape could not settle the species ⁶⁴. A routine tumor workup asks what the tumor is; the tests that would find a parasite are added when someone suspects one ²⁶.

Damage to molecular tests is real, and iodine has one documented entry: the Lugol's-and-thiosulfate step that clears mercury from B-5-fixed slides abolished antibody staining for CD5, CD30 and synaptophysin in a 2003 test ¹⁷. The other documented sources are not iodine. Decalcifying with hydrochloric acid, or with formic acid for too long, produced false negatives on both antibody staining and molecular tests of bone ⁷³. Mercury-containing fixatives brought disposal burdens that drove a search for replacements ³⁹. Block age erodes DNA, so archives older than about five years are poor places to look ⁶⁶. And some infections are simply too light: microscopy-negative, PCR-positive Giardia samples behaved like true low-burden infections ¹¹.

What is still unknown

The experiment that would settle the question has not been published. It would take tissue known to contain a parasite, expose paired pieces to iodine at skin-preparation and chromoendoscopy strengths and contact times, chromoendoscopy being endoscopy with a dye such as Lugol's sprayed on the lining so that abnormal areas stand out, or leave them unexposed, fix and section both, and have pathologists who do not know which is which read them, with PCR on the same blocks. No study found for this page measured how iodine exposure before fixation affects recovery of parasite DNA; the one test of iodine before biopsy measured human gene expression in the cervix and found no substantial change ⁶⁸, and recovery from fixed blocks without iodine is well documented ^19,66. Nor did the searches find any study of whether the iodinated contrast given for scans before surgery affects parasites in tissue.

Smaller facts also remain open. How often mercury fixatives, and with them the iodine clearing step, are still used was not established ^17,39. Whether Lugol's painted on a cervix in a schistosomiasis-endemic area changes the yield of eggs in the biopsy that follows has not been studied as such, although eggs are common in such cervices ^25,76 and have been read in a specimen taken after an iodine-negative colposcopy ⁷⁷. Whether iodine's structural damage to amoeba cysts in suspension ⁵⁹ has any counterpart for a helminth or an egg in solid tissue is untested. And the popular sources in which ideas like this one circulate are not indexed, so their exact claims about iodine could not be checked for this page.

How this connects to parasites and cancer

Parasites causing cancer is not a fringe idea. Three are classed by the International Agency for Research on Cancer, the World Health Organization's cancer agency, in Group 1, definite human carcinogens: the liver flukes Clonorchis sinensis and Opisthorchis viverrini and the blood fluke Schistosoma haematobium ⁷¹. That classification comes from the IARC Monographs working group of 2009 ⁷⁸. The scale matters too: IARC's 2026 estimate attributes 2.3 million new cancers in 2024, 12% of all cases, to twelve Group 1 infectious agents, a list that includes the three parasites but whose five largest contributors, Helicobacter pylori, human papillomavirus, hepatitis B virus, Epstein-Barr virus and hepatitis C virus, together account for nearly all of the 2.3 million ⁷⁹. Parasites cause cancer; by that arithmetic they cause a small share of it. Pathology finds these parasites beside their cancers through the same biopsies, antiseptics and fixatives the iodine hypothesis suspects; in one 2017 report, schistosome eggs sat in the bladder wall of the biopsy that diagnosed the cancer ⁶³. A pipeline that produced such findings is not blind to dead parasites, though it can certainly miss sparse ones ²⁵.

The cervix is where Lugol's iodine and a carcinogenic parasite most often meet. Lugol's is painted on it for colposcopy and screening ^6,7, and in endemic areas S. haematobium eggs lodge there: in the cervix of 49% of 228 Tanzanian women by direct biopsy examination ²⁵, and in cervicovaginal lavage, a rinse of the vagina and cervix, from 25.5% of 55 Malawian women with urogenital schistosomiasis in 2025 ⁷⁶. Female genital schistosomiasis is diagnosed mainly by colposcopy ⁷⁶ and is widely described as a risk factor for HIV, the virus that causes AIDS, for human papillomavirus (HPV) and for cervical dysplasia, but the evidence is cross-sectional and uneven: in a 2026 report on 2,532 Zambian women, schistosome DNA in the cervix was only weakly associated with high-risk HPV (an adjusted odds ratio of 1.3, where 1.0 means no association, with a range of 0.9 to 1.9 that includes it; 1.7 for the most dangerous types, 16, 18 and 45), and lesions seen at colposcopy were not associated with HPV at all ⁸⁰. Colposcopy itself misses most infections: in a 2026 study of 143 Cameroonian women it found 23% where PCR of a genital swab found 73%, a sensitivity of 38% against a statistical reference standard ⁸¹, which is a sampling and recognition gap of the kind this page describes, not an iodine effect. Whether iodine at colposcopy affects egg detection has not been studied as such, but the record holds two direct observations: in a 44-year-old HIV-positive woman in 2015, colposcopy showed a dense acetowhite area that took no iodine, and the surgical specimen showed numerous calcified S. haematobium eggs ⁷⁷; and in a 28-year-old immigrant in 2012, colposcopy showed pale-yellow granular lesions and histology found calcified eggs that urine and stool had missed ⁸². In the first, Lugol's demonstrably touched the cervix and the eggs were read anyway; the second does not say which stains were used.

An iodine stain has even produced a parasite-cancer association. In 107 Polish patients with colorectal cancer, an iodine-stained stool smear found Blastocystis, a common intestinal protozoan, in 12.15% against 2.42% of 124 controls, and PCR agreed almost exactly, 12.63% against 2.63% ⁸³. That is an association measured before cancer treatment, and the authors read it as opportunistic infection, one that takes hold because the body's defenses are weakened, in people with cancer rather than as a cause ⁸³. It is also a plain example of an iodine method and a DNA test finding the same parasite at the same rate ⁸³.

That leaves the iodine hypothesis at the lowest evidence class there is: no study supports it, none has tested it directly, and the adjacent studies point away from it. It belongs to a wider popular current in which antiparasitic remedies are promoted for cancer; a 2022 study of Korean YouTube found 702 videos from 227 channels about taking the dog dewormer fenbendazole for cancer, with recommendation algorithms reinforcing the belief despite government warnings ⁸⁴. The current has since reached the indexed literature and the emergency room. In 2026 the journal Anticancer Research placed a formal Expression of Concern on a paper reporting an '84.4% clinical benefit ratio' for ivermectin and mebendazole in a self-reported cohort of 197 cancer patients, pending an audit of whether the patients, their diagnoses and the ethical approval could be verified ⁸⁵; the same year brought a report of severe liver injury in a 65-year-old man taking veterinary fenbendazole and ivermectin for prostate cancer ⁸⁶ and of life-threatening neurotoxicity from high-dose ivermectin taken for metastatic breast cancer, both traced by their authors to online claims ⁸⁷. Iodine is not part of these claims; the hypothesis this page examines lives upstream of them, in the idea that parasites are the hidden cause. The season's earlier research traced related claims to popular books, among them Hulda Clark's, which PubMed does not index and which are not quoted here. If you have wondered whether iodine is hiding parasites in tumors, it was a fair thing to wonder, and the evidence answers no: iodine is far better documented as a way of finding parasites than of hiding them ^10,11, and the real gaps are sampling and attention ^25,26.

Where it connects

Sources

87 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
   Darouiche RO, Wall MJ, Itani KM, et al. Chlorhexidine-Alcohol versus Povidone-Iodine for Surgical-Site Antisepsis.N Engl J Med · 2010 · 362(1):18-26doi:10.1056/NEJMoa0810988 · PMID 20054046

   Randomized trial in 849 adults having clean-contaminated surgery: chlorhexidine-alcohol 9.5% versus povidone-iodine scrub and paint 16.1% surgical-site infection. It counts wound infections, not specimens. Its PubMed record carries no funding statement; the article's own disclosures, not reproduced in the record, report support from Cardinal Health, the maker of the chlorhexidine-alcohol preparation it tested (ClinicalTrials.gov NCT00290290).

2. 2
   Lepelletier D, Maillard JY, Pozzetto B, Simon A. Povidone Iodine: Properties, Mechanisms of Action, and Role in Infection Control and Staphylococcus aureus Decolonization.Antimicrob Agents Chemother · 2020 · 64(9):e00682-20doi:10.1128/AAC.00682-20 · PMID 32571829

   Review written from an expert workshop on povidone-iodine for decolonization, citing 10% and 7.5% solutions; the organism name is stripped from the record's title and restored here. The record does not say who convened or funded the workshop. Cited for the product strengths; the review concerns nasal decolonization, not surgical skin preparation, and the 2010 trial's abstract describes its arm only as a povidone-iodine scrub and paint [1].

3. 3
   Sprague S, Slobogean G, Wells JL, et al. (PREP-IT investigators). Skin Antisepsis before Surgical Fixation of Extremity Fractures.N Engl J Med · 2024 · 390(5):409-420doi:10.1056/NEJMoa2307679 · PMID 38294973

   The PREPARE trial at 25 hospitals: 0.7% iodine povacrylex in alcohol gave fewer infections than chlorhexidine in alcohol after closed fractures (2.4% vs 3.3%), not after open ones. Publicly funded (PCORI and the Canadian Institutes of Health Research); about wound infection only.

4. 4
   Jin D, Wang J, Zhan Q, et al. The safety and efficacy of 2% vitamin C solution spray for relief of mucosal irritation caused by Lugol chromoendoscopy: a multicenter, randomized, double-blind, parallel trial.Gastrointest Endosc · 2019 · 92(3):554-564doi:10.1016/j.gie.2019.11.028 · PMID 31783028

   Trial in 240 patients after 10 mL of 2% Lugol's: vitamin C and thiosulfate both reduced symptoms against saline. The abstract's vitamin C versus thiosulfate decolorization figures look internally inconsistent and are not quoted here.

5. 5
   Qu JY, Li Y, Liu GQ, et al. Optimal concentration of Lugol's solution for detecting early esophageal carcinoma: A randomized controlled trial.J Gastroenterol Hepatol · 2023 · 38(6):962-969doi:10.1111/jgh.16190 · PMID 37094943

   Two-phase randomized trial (200 then 42 patients): 0.6% Lugol's caused less gastric mucosal injury than stronger solutions with no loss of image quality. Single center; image quality and comfort, not cancer detection rates.

6. 6
   Reich O, Pickel H. 100 years of iodine testing of the cervix: A critical review and implications for the future.Eur J Obstet Gynecol Reprod Biol · 2021 · 261:34-40doi:10.1016/j.ejogrb.2021.04.011 · PMID 33873086

   Historical review: Ehrlich's glycogen staining, Schiller's choice of Lugol's iodine from nearly 200 dyes, Lahm's 1928 observation that glycogen falls with anaplasia, and visual inspection with Lugol's iodine for screening. History, not new data.

7. 7
   Sankaranarayanan R, Basu P, Wesley RS, et al. Accuracy of visual screening for cervical neoplasia: Results from an IARC multicentre study in India and Africa.Int J Cancer · 2004 · 110(6):907-13doi:10.1002/ijc.20190 · PMID 15170675

   Eleven cross-sectional studies in 56,939 women: visual inspection with Lugol's iodine had 91.7% sensitivity and 85.4% specificity for high-grade lesions. Accuracy for precancer, not anything about parasites.

8. 8
   Sugimachi K, Tsutsui S, Kitamura K, et al. Lugol stain for intraoperative determination of the proximal surgical margin of the esophagus.J Surg Oncol · 1991 · 46(4):226-9doi:10.1002/jso.2930460404 · PMID 1706814

   Describes bathing the opened resected esophagus in 1% Lugol's for 2 to 3 minutes to show carcinoma as unstained; glycogen-rich normal lining turns greenish-brown. A technique report, not a comparison.

9. 9
   Mori M, Adachi Y, Matsushima T, et al. Lugol staining pattern and histology of esophageal lesions.Am J Gastroenterol · 1993 · 88(5):701-5PMID 7683176

   Lugol's test applied to 24 resected esophagi, then histology: unstained zones were mostly invasive carcinoma, carcinoma in situ or severe dysplasia, and stain intensity tracked the glycogen layer. Shows histology reading iodine-stained tissue; no parasites involved. No DOI in the record.

10. 10
    Mewara A, Khurana S, Gupta S, et al. Diagnostic performance of mini parasepsolvent-free foecal parasite concentrator for the diagnosis of intestinal parasitic infections.Indian J Med Microbiol · 2019 · 37(3):381-386doi:10.4103/ijmm.IJMM_19_44 · PMID 32003337

    150 stool samples examined by wet mount and iodine mount after three preparations; the 90.1% sensitivity belongs to direct microscopy and the better yield to the concentrator, not to iodine. Shows iodine mounts as routine detection; it evaluates a branded device.

11. 11
    Helmy MM, Abdel-Fattah HS, Rashed L. Real-time PCR/RFLP assay to detect Giardia intestinalis genotypes in human isolates with diarrhea in Egypt.J Parasitol · 2009 · 95(4):1000-4doi:10.1645/GE-1670.1 · PMID 19254068

    In 97 stools, Lugol's-stained microscopy found Giardia in 31% and PCR in 42.3%; the microscopy-negative positives behaved like low-burden infections. Shows misses from low numbers, not from iodine.

12. 12
    Ongerth JE, Johnson RL, Macdonald SC, et al. Back-country water treatment to prevent giardiasis.Am J Public Health · 1989 · 79(12):1633-7doi:10.2105/ajph.79.12.1633 · PMID 2817191

    At 10 °C no chemical treatment inactivated 99.9% of Giardia cysts in 30 minutes; every iodine product did so by 8 hours. Water treatment in vitro, at concentrations far below skin preparations.

13. 13
    Labare MP, Soohoo H, Kim D, et al. Ineffectiveness of a quaternary ammonium salt and povidone-iodine for the inactivation of Ascaris suum eggs.Am J Infect Control · 2012 · 41(4):360-1doi:10.1016/j.ajic.2012.05.013 · PMID 23102984

    Povidone-iodine at 1%, 10%, 50% and 100% had no effect on unembryonated Ascaris suum eggs over 5 to 120 minutes; phenol and cresol did inactivate them. A short report on a pig roundworm's eggs, in vitro.

14. 14
    Zhang R, Lu M, Yu H, et al. Evaluation of the efficacy of disinfectants and disinfection methods against Ascaris suum eggs.Vet Parasitol · 2024 · 332:110333doi:10.1016/j.vetpar.2024.110333 · PMID 39437589

    Eight disinfectants, ultraviolet light and quicklime against A. suum eggs incubated 15 days at 22 to 25 °C: 5% and 10% povidone-iodine for 30 to 120 minutes, and 1% to 10% over 15 days, completely inhibited development to the second larval stage. Pig roundworm, in vitro; the endpoint is development, not the immediate viability measured in 2012 [16].

15. 15
    Heaselgrave W, Hamad A, Coles S, Hau S. In Vitro Evaluation of the Inhibitory Effect of Topical Ophthalmic Agents on [Acanthamoeba] Viability.Transl Vis Sci Technol · 2019 · 8(5):17doi:10.1167/tvst.8.5.17 · PMID 31588380

    In vitro: some anesthetic drops and benzalkonium-preserved drops harmed Acanthamoeba, and the authors warn they may cause false-negative tests if applied before sampling. Povidone-iodine was among the agents tested and showed antiamoebic activity above the diamidines and slightly below the biguanides; the false-negative warning itself names the anesthetics and benzalkonium chloride, not povidone-iodine.

16. 16
    Hoffman JJ, Dart JKG, De SK, et al. Comparison of culture, confocal microscopy and PCR in routine hospital use for microbial keratitis diagnosis.Eye (Lond) · 2021 · 36(11):2172-2178doi:10.1038/s41433-021-01812-7 · PMID 34741122

    Retrospective review of 259 microbial keratitis patients with PCR results, culture for 203 and confocal microscopy for 149: against a composite reference of a positive result on any test, Acanthamoeba keratitis sensitivity was 77.1% for confocal microscopy, 63.3% for PCR and 35.6% for culture. Shows that the viability-based test misses most; single center.

17. 17
    Wan X, Cochran G, Greiner TC. Removal of mercuric chloride deposits from B5-fixed tissue will affect the performance of immunoperoxidase staining of selected antibodies.Appl Immunohistochem Mol Morphol · 2003 · 11(1):92-5doi:10.1097/00129039-200303000-00015 · PMID 12610363

    Paired immunoperoxidase staining of 75 antibodies with and without the Lugol's iodine and 5% sodium thiosulfate clearing step: CD5, CD30 and synaptophysin totally lost, ALK, Ulex and GFAP reduced. The one indexed demonstration found of iodine causing a false-negative result on fixed tissue; it concerns antigens, not morphology or parasites.

18. 18
    Thavarajah R, Mudimbaimannar VK, Elizabeth J, et al. Chemical and physical basics of routine formaldehyde fixation.J Oral Maxillofac Pathol · 2012 · 16(3):400-5doi:10.4103/0973-029X.102496 · PMID 23248474

    Narrative review of formalin chemistry: an ideal fixative hardens tissue and prevents decomposition and autolysis; 10% formalin is about 4% formaldehyde. The hardening and autolysis statements come from the full text, not the abstract; the concentration is also stated in the abstract of [58].

19. 19
    Safaei A, Motazedian MH, Vasei M. Polymerase chain reaction for diagnosis of cutaneous leishmaniasis in histologically positive, suspicious and negative skin biopsies.Dermatology · 2002 · 205(1):18-24doi:10.1159/000063150 · PMID 12145429

    PCR on paraffin blocks detected Leishmania in all 33 microscopy-positive and 24 of 29 microscopy-negative clinical cases: 92% sensitivity, 100% specificity. Shows DNA surviving fixation; one center.

20. 20
    Widmer AF, Atkinson A, Kuster SP, et al. Povidone Iodine vs Chlorhexidine Gluconate in Alcohol for Preoperative Skin Antisepsis: A Randomized Clinical Trial.JAMA · 2024 · 332(7):541-549doi:10.1001/jama.2024.8531 · PMID 38884982

    Cluster-randomized crossover trial in 3,360 Swiss cardiac and abdominal surgery patients: povidone-iodine in alcohol noninferior to chlorhexidine in alcohol (infection 5.1% vs 5.5%). Academic authors; says nothing about specimens.

21. 21
    Kondo H, Fukuda H, Ono H, et al. Sodium thiosulfate solution spray for relief of irritation caused by Lugol's stain in chromoendoscopy.Gastrointest Endosc · 2001 · 53(2):199-202doi:10.1067/mge.2001.110730 · PMID 11174292

    Randomized trial in 120 healthy men given 10 mL of Lugol's on the esophagus: 5% sodium thiosulfate spray relieved lasting symptoms; antacid gel did not. Shows iodine reaching the lining in irritating amounts, not any effect on specimens.

22. 22
    Metscher BD. MicroCT for comparative morphology: simple staining methods allow high-contrast 3D imaging of diverse non-mineralized animal tissues.BMC Physiol · 2009 · 9:11doi:10.1186/1472-6793-9-11 · PMID 19545439

    Methods paper introducing inorganic iodine and phosphotungstic acid stains for micro-CT of fixed animal tissue, non-destructively. Research imaging, not diagnostic pathology.

23. 23
    Mariani PP, van Pelt JF, Ectors N, et al. Rectal washout with cytotoxic solution can be extended to the whole colon.Br J Surg · 2002 · 89(12):1540-4doi:10.1046/j.1365-2168.2002.02224.x · PMID 12445063

    14 patients: retrograde whole-colon lavage with 5% povidone-iodine and 12% Gastrografin reached the cecum in 2 minutes; 100% tumoricidal in vitro; superficial epithelial desquamation restored by 7 days; transient fall in serum T3. Documents iodine and an iodinated contrast agent on the lining of a cancer specimen, and a measured tissue effect.

24. 24
    Reyazulla MA, Gopinath AL, Vaibhav N, Raut RP. An unusual complication of late onset allergic contact dermatitis to povidone iodine in oral & maxillofacial surgery - a report of 2 cases.Eur Ann Allergy Clin Immunol · 2014 · 46(4):157-9PMID 25053635

    Two-case report whose introduction describes povidone-iodine as a complex of polyvinylpyrrolidone and iodine with a low free-iodine concentration. Cited only for that description; no DOI in the record.

25. 25
    Poggensee G, Sahebali S, Van Marck E, et al. Diagnosis of genital cervical schistosomiasis: comparison of cytological, histopathological and parasitological examination.Am J Trop Med Hyg · 2001 · 65(3):233-6doi:10.4269/ajtmh.2001.65.233 · PMID 11561710

    In 228 Tanzanian women, cervical schistosome eggs were found in 49% by compressed biopsy, 18% by histology and 3% by smear, with histology better at higher egg density. The best measure of sampling loss for a parasite; not about iodine.

26. 26
    Trecourt A, Radobonirina M. [Infectious cysts and pseudocysts: When parasites want to mimic tumors!].Ann Pathol · 2025 · 45(6):513-522doi:10.1016/j.annpat.2025.04.003 · PMID 40328550

    French review: parasitic cysts are rarely seen by pathologists, have many morphological pitfalls and can be misdiagnosed; it advises expert review and histo-molecular diagnosis. Expert opinion with no pooled numbers.

27. 27
    Gerba CP, Johnson DC, Hasan MN. Efficacy of iodine water purification tablets against Cryptosporidium oocysts and Giardia cysts.Wilderness Environ Med · 1997 · 8(2):96-100doi:10.1580/1080-6032(1997)008[0096:eoiwpt]2.3.co;2 · PMID 11990150

    Iodine tablets at 13 to 18 mg/L for 20 minutes: 3-log Giardia inactivation in ordinary water but about 35% at pH 5; Cryptosporidium 10% at 20 minutes and 66% to 81% at 240 minutes. In vitro water testing.

28. 28
    Rajaraman R, Kassaye I, Sharma SS, et al. Adjunctive povidone-iodine for [Acanthamoeba] keratitis: a randomized trial.Antimicrob Agents Chemother · 2026 · 70(5):e0151225doi:10.1128/aac.01512-25 · PMID 41914638

    49 patients: adding 2.5% then 1% povidone-iodine to chlorhexidine left 33% versus 31% culture-positive at 4 weeks (relative risk 0.90, 95% confidence interval 0.35 to 2.29); 4 of 25 (16%) stopped the 2.5% drops for intolerance. The wide interval means the trial could not exclude a benefit; the abstract itself does not call the study underpowered or discuss corneal penetration. Academic authors.

29. 29
    Vickerton P, Jarvis J, Jeffery N. Concentration-dependent specimen shrinkage in iodine-enhanced microCT.J Anat · 2013 · 223(2):185-93doi:10.1111/joa.12068 · PMID 23721431

    Mouse tissues in iodine-potassium iodide stain shrank far more than in fixatives, up to 70% in 20% solution after 14 days. Shows iodine distorting tissue at research-imaging doses and durations.

30. 30
    Sunada A, Kimura K, Nishi I, et al. In vitro evaluations of topical agents to treat Acanthamoeba keratitis.Ophthalmology · 2014 · 121(10):2059-65doi:10.1016/j.ophtha.2014.04.013 · PMID 24880905

    Cysts from 56 patients: 1.0% povidone-iodine was second only to natamycin at complete growth inhibition after 1 or 24 hours. The authors hedge between cyst-static and cysticidal; in vitro only.

31. 31
    Moazeni M, Hosseini SV, Al-Qanbar MH, et al. In vitro evaluation of the protoscolicidal effect of Eucalyptus globulus essential oil on protoscolices of hydatid cyst compared with hypertonic saline, povidone iodine and silver nitrate.J Visc Surg · 2019 · 156(4):291-295doi:10.1016/j.jviscsurg.2019.01.002 · PMID 30987848

    10% povidone-iodine killed 100% of sheep-derived Echinococcus protoscoleces within 1 minute in vitro, in a study promoting an essential oil. Shows iodine killing a tapeworm larva fast; says nothing about pathology.

32. 32
    Umpleby HC, Williamson RC. The efficacy of agents employed to prevent anastomotic recurrence in colorectal carcinoma.Ann R Coll Surg Engl · 1984 · 66(3):192-4PMID 6232888

    Survey of 72 surgeons, 48 of whom used an intraluminal cytotoxic washout (povidone-iodine in 7) for a mean of 2 minutes, with in vitro cytotoxicity on cells from 10 human colorectal cancers: chlorhexidine-cetrimide and povidone-iodine rapidly lethal at 5% to 100%. Shows iodine deliberately applied to tumor-bearing bowel. No DOI in the record.

33. 33
    Terzi C, Unek T, Sağol O, et al. Is rectal washout necessary in anterior resection for rectal cancer? A prospective clinical study.World J Surg · 2006 · 30(2):233-41doi:10.1007/s00268-005-0300-x · PMID 16425079

    96 patients, 38 with a 5% povidone-iodine rectal washout: no difference in malignant cells on the stapler or in local recurrence. Non-randomized; the authors call it too small for a definite conclusion.

34. 34
    Nakamoto T, Koyama F, Kuge H, et al. In vitro analysis of exfoliated tumor cells in intraluminal lavage samples after colorectal endoscopic submucosal dissection.Int J Colorectal Dis · 2021 · 37(1):161-170doi:10.1007/s00384-021-04037-y · PMID 34599685

    Lavage samples from 19 patients after endoscopic submucosal dissection: exfoliated tumor cells 24% viable and still viable at 12 hours; contact with 2% povidone-iodine significantly reduced viable counts. In vitro.

35. 35
    Sapero JJ, Lawless DK. The MIF stain-preservation technic for the identification of intestinal protozoa.Am J Trop Med Hyg · 1953 · 2(4):613-9doi:10.4269/ajtmh.1953.2.613 · PMID 13065626

    The original 1953 description of the MIF stain-preservative for identifying intestinal protozoa; the record has no abstract, so it is cited only for the method's existence and date.

36. 36
    Caselli M, Libanore M, Ghinelli F, et al. Merthiolate iodine formaldehyde technique for cryptosporidium.Boll Ist Sieroter Milan · 1987 · 66(2):161-2PMID 2444236

    A letter applying the merthiolate-iodine-formaldehyde technique to Cryptosporidium; cited only for what MIF stands for. No abstract or DOI in the record.

37. 37
    Hildebrand T, Haugen HJ, Romandini M, et al. From pulp to cementum: 3D visualization of soft and hard dental tissues using different ex vivo nano-CT contrast-enhancement techniques.Int Endod J · 2025 · 58(8):1228-1242doi:10.1111/iej.14260 · PMID 40407252

    Ten human molars were decalcified and then treated with Lugol's iodine for nano-CT, compared with classical histology. The only route found by which iodine meets decalcified tissue, and it is research imaging.

38. 38
    Facchetti F, Alebardi O, Vermi W. Omit iodine and CD30 will shine: a simple technical procedure to demonstrate the CD30 antigen on B5-fixed material.Am J Surg Pathol · 2000 · 24(2):320-2doi:10.1097/00000478-200002000-00039 · PMID 10680909

    Letter without an abstract in the record; cited for its title and for the existence of the iodine clearing step on B-5-fixed material.

39. 39
    Bonds LA, Barnes P, Foucar K, Sever CE. Acetic acid-zinc-formalin: a safe alternative to B-5 fixative.Am J Clin Pathol · 2005 · 124(2):205-11doi:10.1309/29DA-CY9K-BHNW-4BG6 · PMID 16040290

    Blinded comparison: a mercury-free fixative matched mercury-based B-5 for morphology and immunostaining; the abstract cites costly mercury disposal and labor-intensive B-5 steps. It does not describe the iodine step itself.

40. 40
    Berkelman RL, Holland BW, Anderson RL. Increased bactericidal activity of dilute preparations of povidone-iodine solutions.J Clin Microbiol · 1982 · 15(4):635-9doi:10.1128/jcm.15.4.635-639.1982 · PMID 7040461

    Laboratory study: Staphylococcus aureus survived 2 minutes in full-strength 10% povidone-iodine but not 15 seconds in a 1:100 dilution. Bacteria only; it does not test parasites.

41. 41
    Brownell SA, Nelson KL. Inactivation of single-celled Ascaris suum eggs by low-pressure UV radiation.Appl Environ Microbiol · 2006 · 72(3):2178-84doi:10.1128/AEM.72.3.2178-2184.2006 · PMID 16517669

    Ascaris eggs, with a 3- to 4-micrometer shell, were the most UV-resistant water pathogen known to the authors; stripping the outer shell raised susceptibility. About ultraviolet light, not iodine; cited for shell structure.

42. 42
    Aterman K. A historical note on the iodine-sulphuric acid reaction of amyloid.Histochemistry · 1976 · 49(2):131-43doi:10.1007/BF00495677 · PMID 791904

    History of the iodine reaction from the 1814 starch test to Virchow's 1853 use on a waxy spleen, the first histochemical reaction for amyloid. Historical, not experimental.

43. 43
    Uslu H, Aktas O, Uyanik MH. Comparison of Various Methods in the Diagnosis of Entamoeba histolytica in Stool and Serum Specimens.Eurasian J Med · 2016 · 48(2):124-9doi:10.5152/eurasianjmed.2015.0074 · PMID 27551176

    In 90 patients called Entamoeba histolytica or dispar by saline and Lugol's mounts, antigen tests failed to confirm 62.2% and 64.4%. The error documented is overcalling, because microscopy cannot separate the two species.

44. 44
    Katada C, Yokoyama T, Yano T, et al. Alcohol Consumption and Multiple Dysplastic Lesions Increase Risk of Squamous Cell Carcinoma in the Esophagus, Head, and Neck.Gastroenterology · 2016 · 151(5):860-869.e7doi:10.1053/j.gastro.2016.07.040 · PMID 27492616

    Prospective study of 331 patients after endoscopic resection of early esophageal cancer: new esophageal cancers in 4%, 9.4% and 24.7% by grade of Lugol-voiding lesions. Shows what the stain measures; observational.

45. 45
    Thornton SA, West AH, DuPont HL, Pickering LK. Comparison of methods for identification of Giardia lamblia.Am J Clin Pathol · 1983 · 80(6):858-60doi:10.1093/ajcp/80.6.858 · PMID 6637891

    Day-care stool specimens screened by methylene blue and dilute Lugol's wet mounts, merthiolate-iodine-formalin concentration and trichrome: trichrome and the concentration were best for cysts, and the wet mounts significantly less accurate. A quantification scheme, not PCR; US Public Health Service funded.

46. 46
    Lim L, Coster DJ, Badenoch PR. Antimicrobial susceptibility of 19 Australian corneal isolates of Acanthamoeba.Clin Exp Ophthalmol · 2000 · 28(2):119-24doi:10.1046/j.1442-9071.2000.00275.x · PMID 10933775

    In 19 corneal isolates exposed for 7 days, povidone-iodine had poor activity; the authors found no clear link between laboratory susceptibility and visual outcome. In vitro.

47. 47
    Nesbit SE, Hong I, O'Hara NN, et al. Can a Targeted Dissemination Strategy of the PREPARE Trial Results Change Surgical Antiseptic Practice?Clin Orthop Relat Res · 2026 · 484(8):1545-1554doi:10.1097/CORR.0000000000003925 · PMID 42008801

    Single-center before-and-after study: iodine povacrylex use in fracture surgery rose from 0.8% to 86% after the PREPARE results were publicized. Shows current practice at one hospital, not outcomes; one author, Sprague S, is also a PREPARE author.

48. 48
    Yang S, Li Z, Wu F, et al. Chlorhexidine versus povidone-iodine for surgical site infection prevention: an updated meta-analysis and trial sequential analysis of randomized controlled trials.Front Med (Lausanne) · 2025 · 12:1641815doi:10.3389/fmed.2025.1641815 · PMID 41357507

    32 randomized trials, 29,748 participants: chlorhexidine relative risk 0.83 (0.72 to 0.95) overall, superior in clean-contaminated (0.75) but not clean surgery, and for superficial but not deep or organ-space infections.

49. 49
    Wang L, Xu S, Xu Q, Xiao J. Comparing the efficacy of chlorhexidine and povidone-iodine for surgical site disinfection: a systematic review and meta-analysis from randomized controlled trials.Ann Med · 2026 · 58(1):2634531doi:10.1080/07853890.2026.2634531 · PMID 41755546

    26 trials, 29,356 patients: infections 7.1% versus 7.8%, relative risk 0.89 (0.80 to 0.99), absolute reduction 0.7%, number needed to treat 143; no difference for deep or organ-space infection.

50. 50
    Morita FH, Bernardo WM, Ide E, et al. Narrow band imaging versus lugol chromoendoscopy to diagnose squamous cell carcinoma of the esophagus: a systematic review and meta-analysis.BMC Cancer · 2017 · 17(1):54doi:10.1186/s12885-016-3011-9 · PMID 28086818

    Meta-analysis of 12 studies, 1,911 patients: Lugol's per-patient sensitivity 92% and specificity 82%; narrow band imaging 88% and 88%, significantly more specific. About finding cancer, not parasites.

51. 51
    Ogata Y, Hatta W, Koike T, et al. Is blue light imaging without magnification satisfactory as screening for esophageal squamous cell carcinoma? Post-hoc analysis of multicenter randomized controlled trial.Dig Endosc · 2024 · 36(10):1118-1126doi:10.1111/den.14788 · PMID 38494659

    699 high-risk patients, 49 cancers; blue-light imaging without magnification missed 9 (18.4%) that Lugol's then detected; per-patient sensitivity 83.7% versus 100%, specificity 88.2% versus 81.2%. Post hoc, expert centers.

52. 52
    Liu M, Yang W, Guo C, et al. Effectiveness of Endoscopic Screening on Esophageal Cancer Incidence and Mortality: A 9-Year Report of the Endoscopic Screening for Esophageal Cancer in China (ESECC) Randomized Trial.J Clin Oncol · 2024 · 42(14):1655-1664doi:10.1200/JCO.23.01284 · PMID 38457759

    Cluster-randomized trial in 668 villages, 33,847 participants: Lugol's chromoendoscopy screening gave an incidence hazard ratio of 0.81 (0.60 to 1.09) and a mortality hazard ratio of 0.82 (0.53 to 1.26) by intention to treat. A randomized test of the stain against cancer deaths.

53. 53
    Da Costa A, Mansourati J, Eschalier R, et al. Chlorhexidine vs Povidone-Iodine Alcohol Solutions for Cardiac Implantable Electronic Devices: A Prospective Randomized Study.J Am Coll Cardiol · 2026 · 87(2):200-211doi:10.1016/j.jacc.2025.10.042 · PMID 41562534

    CHLOVIS: 2,272 patients, 24-month follow-up; device infection 2.9% with chlorhexidine versus 3.9% with povidone-iodine, adjusted subhazard ratio 0.75 (0.48 to 1.20), not significant. Academic, publicly registered.

54. 54
    Pelletier JS, Miller D, Liang B, Capriotti JA. In vitro efficacy of a povidone-iodine 0.4% and dexamethasone 0.1% suspension against ocular pathogens.J Cataract Refract Surg · 2011 · 37(4):763-6doi:10.1016/j.jcrs.2010.11.028 · PMID 21420603

    0.4% povidone-iodine with dexamethasone killed three bacteria and Candida within 15 seconds but did not inhibit Acanthamoeba cysts. Two authors declare no interest; further disclosures sit in footnotes the record does not reproduce.

55. 55
    Muthukumar V, Shi L, Chai N, et al. Efficacy of Off-Label Anti-Amoebic Agents to Suppress Trophozoite Formation of [Acanthamoeba] spp. on Non-Nutrient Agar [Escherichia coli] Plates.Microorganisms · 2022 · 10(8):1642doi:10.3390/microorganisms10081642 · PMID 36014060

    Of eight drugs, only 1% povidone-iodine completely stopped challenged cysts forming active amoebae in all four isolates and five replicates. Organism names are stripped from the record's title and restored in brackets; in vitro.

56. 56
    Randag AC, de Kroon L, Otten H, et al. In Vitro Effectiveness of Soft Contact Lens Solutions Available on the Dutch Market against [Acanthamoeba] Species.Pathogens · 2023 · 12(2):214doi:10.3390/pathogens12020214 · PMID 36839486

    Sixteen lens solutions, one povidone-iodine-based: cysts were resistant to all. One author lists a contact-lens retailer as affiliation; the rest are hospital, university and public-health institute staff. In vitro.

57. 57
    Pastrana C, Huete-Toral F, Privado-Aroco A, Carracedo G. Efficacy of different disinfecting methods for contact lenses against Acanthamoeba castellanii.Cont Lens Anterior Eye · 2024 · 48(2):102326doi:10.1016/j.clae.2024.102326 · PMID 39523151

    Lenses contaminated for 24 hours; survival read by RNA-based PCR for Hsp70 and TPBF. Povidone-iodine alone left 38% of hydrogel and 12% of silicone-hydrogel lenses positive; 100% negative with a cleaner first. In vitro; university optometry group.

58. 58
    Ponce-García V, García-Romera MC, Silva-Viguera MC, Bautista-Llamas MJ. Antimicrobial efficacy of multipurpose and oxidative contact lens disinfecting solutions: a systematic review.Cont Lens Anterior Eye · 2026 · 49(2):102605doi:10.1016/j.clae.2026.102605 · PMID 41520504

    Ten studies: oxidative systems (hydrogen peroxide, povidone-iodine) consistently effective, including against clinical isolates and biofilm; multipurpose solutions variable against fungi and Acanthamoeba cysts; the ISO 14729 standard omits Acanthamoeba.

59. 59
    Roongruangchai J, Sookkua T, Kummalue T, Roongruangchai K. Pouzolzia indica methanolic extract fraction 2 and povidone-iodine induced changes in the cyst of Acanthamoeba spp.: light and electron microscopic studies.J Med Assoc Thai · 2009 · 92(11):1492-9PMID 19938742

    At its minimum cysticidal concentration of 0.04%, povidone-iodine shrank and ruptured Acanthamoeba cyst walls until cysts were torn into pieces. The strongest evidence that iodine can destroy a protozoan's structure, in suspension; no DOI in the record.

60. 60
    Bahr C, Kitamura M, Shibaike Y, et al. Time-Lapse Tracking of Acanthamoeba castellanii Trophozoite Activity During Exposure to Contact Lens Disinfectants.Invest Ophthalmol Vis Sci · 2025 · 66(11):50doi:10.1167/iovs.66.11.50 · PMID 40844809

    0.05% povidone-iodine stopped trophozoite movement within 2 minutes with no recovery. Commercial interest: all five authors are affiliated with Ophtecs Corporation's laboratory, and the record carries no conflict statement. Trophozoites only, in vitro.

61. 61
    Gökçe ON, Çetin K, Taş Ş, Alkan S, Dinç U. Hypochlorous Acid: A Novel Agent Against [Echinococcus granulosus] Protoscoleces.Infect Dis Clin Microbiol · 2023 · 5(2):158-164doi:10.36519/idcm.2023.238 · PMID 38633006

    In vitro: hypochlorous acid 100% effective in 5 minutes down to a 1/100 dilution; undiluted 10% povidone-iodine and 0.04% chlorhexidine effective at all study times. The organism name is stripped from the record's title and restored in brackets.

62. 62
    Baak JP, Noteboom E, Koevoets JJ. The influence of fixatives and other variations in tissue processing on nuclear morphometric features.Anal Quant Cytol Histol · 1989 · 11(4):219-24PMID 2669781

    Guinea-pig liver morphometry study whose abstract states that 10% formalin is 4% formaldehyde; cited only for that equivalence. No DOI in the record.

63. 63
    Srougi V, Gallucci FP, Mattedi RL, Srougi M. Carcinosarcoma of the bladder following local schistosomiasis infection.BMJ Case Rep · 2017 · 2017doi:10.1136/bcr-2016-218642 · PMID 28325721

    A biopsy showed poorly differentiated bladder cancer with Schistosoma eggs embedded in the bladder wall. One case: proves possibility, not frequency.

64. 64
    Nagayasu E, Kasai T, Ishikura H, et al. Unusual aspect of cuticular morphology in human pulmonary dirofilariasis.Parasitol Int · 2026 · 116:103337doi:10.1016/j.parint.2026.103337 · PMID 42425441

    A filarial worm in a resected lung nodule was described from fixed tissue, but its cuticle made the species ambiguous until 12S rRNA from the paraffin block resolved it. A single case; the worm is a roundworm, not a fluke.

65. 65
    Muehlenbachs A, Bhatnagar J, Agudelo CA, et al. Malignant Transformation of Hymenolepis nana in a Human Host.N Engl J Med · 2015 · 373(19):1845-52doi:10.1056/NEJMoa1505892 · PMID 26535513

    A man with HIV had tumors of tapeworm cells that were unrecognizable as tapeworm tissue until eukaryote-targeted PCR named them. A single case: shows recognition failing, not reagents.

66. 66
    Grimm J, Krickl J, Beck A, et al. Establishing and evaluation of a polymerase chain reaction for the detection of Echinococcus multilocularis in human tissue.PLoS Negl Trop Dis · 2021 · 15(2):e0009155doi:10.1371/journal.pntd.0009155 · PMID 33630840

    A 12S rDNA PCR found Echinococcus DNA in fixed blocks, 9 of 15 viable-lesion samples and all 6 kept under six years; the authors advise blocks under five years. Shows block age as a real limit.

67. 67
    Diaz AZ, Kassaye I, Keenan JD. Acanthamoeba Keratitis: Recent Advances in Diagnosis and Management.Cornea · 2026 · 45(8):941-946doi:10.1097/ICO.0000000000004205 · PMID 42348670

    Scoping review of 2020 to 2025 work: povidone-iodine shows potential benefit on limited evidence; PCR matches or beats culture; viability PCR is emerging. Shares authors with the 2026 trial, so not an independent assessment.

68. 68
    Wang SS, Dasgupta A, Sherman ME, et al. Towards improved biomarker studies of cervical neoplasia: effects of precolposcopic procedures on gene expression patterns.Diagn Mol Pathol · 2005 · 14(2):59-64doi:10.1097/01.pas.0000162754.45908.d4 · PMID 15905687

    Six women, three adjacent samples each (frozen; acetic acid; acetic acid plus Lugol's); 4,850 expressed probes; no differentially expressed genes after correction for multiple comparisons. Normal cervix and human RNA, not parasites; NIH-funded.

69. 69
    Xia S, Cheng Y, Zhu H, et al. Improved methodology for identification of cryptomonads: combining light microscopy and PCR amplification.J Microbiol Biotechnol · 2013 · 23(3):289-96doi:10.4014/jmb.1203.03057 · PMID 23462000

    Lugol's solution, the usual fixative for these fragile algae, frequently lost flagella and other organelles that glutaraldehyde preserved. Shows iodine can degrade delicate single-celled structure over days; not a parasite.

70. 70
    Gao X, Patwa AN, Deng Z, et al. Influence of fixation on CA4+ contrast enhanced microCT of articular cartilage and subsequent feasibility for histological evaluation.Am J Transl Res · 2021 · 13(8):8921-8937PMID 34540005

    Rabbit cartilage: the cationic iodinated agent CA4+ in formalin-fixed tissue allowed hematoxylin-eosin and Alcian blue staining but interfered with immunohistochemistry and Safranin O. Animal tissue; one agent; no DOI in the record.

71. 71
    Kim TS, Pak JH, Kim JB, Bahk YY. Clonorchis sinensis, an oriental liver fluke, as a human biological agent of cholangiocarcinoma: a brief review.BMB Rep · 2016 · 49(11):590-597doi:10.5483/bmbrep.2016.49.11.109 · PMID 27418285

    Review stating that Clonorchis sinensis, Opisthorchis viverrini and Schistosoma haematobium are IARC (the International Agency for Research on Cancer) Group 1 carcinogens. A secondary source for the classification.

72. 72
    Hamelin B, Hosch S, Neidhöfer C, et al. Unbiased DNA Pathogen Detection in Tissues: Real-World Experience With Metagenomic Sequencing in Pathology.Lab Invest · 2025 · 106(1):104254doi:10.1016/j.labinv.2025.104254 · PMID 41167475

    623 fixed, embedded samples, November 2021 to April 2025, low-depth DNA metagenomic sequencing: 229 positive (145 bacteria, 37 viruses, 28 fungi, 9 parasites), 60 uninterpretable; validated by targeted PCR and immunohistochemistry where possible. Single center; the abstract names the vendor platforms.

73. 73
    Miquelestorena-Standley E, Jourdan ML, Collin C, et al. Effect of decalcification protocols on immunohistochemistry and molecular analyses of bone samples.Mod Pathol · 2020 · 33(8):1505-1517doi:10.1038/s41379-020-0503-6 · PMID 32094425

    In 35 samples, hydrochloric acid and long formic-acid decalcification produced false negatives on immunohistochemistry and molecular tests; EDTA did not. The documented reagent harm in decalcification; no iodine involved.

74. 74
    Benhammou M, Elraggal D, Saleh S, et al. Chlorhexidine gluconate vs povidone-iodine for surgical site infection prevention: a systematic review and meta-analysis stratified by surgery type, wound classification, antiseptic formulation, and country income, with meta-regression.J Hosp Infect · 2026 · 173:140-153doi:10.1016/j.jhin.2026.04.015 · PMID 42069226

    29 randomized trials, 35,317 patients: alcohol-based chlorhexidine and alcohol-based povidone-iodine comparably effective in most settings; chlorhexidine better in cesarean, abdominal and clean-contaminated surgery and in low- and middle-income countries.

75. 75
    Chaber-Ciopinska A, Kiprian D, Wieszczy P, et al. Narrow-band imaging vs Lugol chromoendoscopy in screening for esophageal squamous cell neoplasia: a randomized trial.Pol Arch Intern Med · 2023 · 133(10)doi:10.20452/pamw.16462 · PMID 36916462

    294 head-and-neck cancer survivors randomized 2:1 to narrow band imaging or Lugol's: positive predictive value per lesion 7.69% versus 8.11%, with fewer biopsies, shorter examinations and better tolerance under narrow band imaging. Only 3 cancers, so it says little about sensitivity.

76. 76
    Stothard JR, Mainga B, Kumwenda D, et al. Microscopic detection and genetic characterization of schistosome eggs within cervicovaginal lavage sediments from cases of female genital schistosomiasis.Parasitology · 2025 · 152(14):1532-1539doi:10.1017/S0031182025100656 · PMID 40765163

    Pilot study of 55 Malawian women with urogenital schistosomiasis: eggs in cervicovaginal lavage in 25.5%. States that genital schistosomiasis is diagnosed mainly by colposcopy and is a risk factor for HIV, HPV and dysplasia; not a cancer study.

77. 77
    Toller A, Scopin AC, Apfel V, et al. An interesting finding in the uterine cervix: Schistosoma hematobium calcified eggs.Autops Case Rep · 2015 · 5(2):41-4doi:10.4322/acr.2015.003 · PMID 26484333

    Single case: colposcopy showed dense acetowhite, iodine-negative epithelium; the surgical specimen showed numerous calcified S. haematobium eggs and high-grade intraepithelial neoplasia. Proves possibility only.

78. 78
    Bouvard V, Baan R, Straif K, et al. A review of human carcinogens--Part B: biological agents.Lancet Oncol · 2009 · 10(4):321-2doi:10.1016/s1470-2045(09)70096-8 · PMID 19350698

    The IARC Monographs Volume 100B working-group summary that classified Schistosoma haematobium, Opisthorchis viverrini and Clonorchis sinensis as Group 1. Primary source for the classification; the record has no abstract, so it is cited for existence and date.

79. 79
    Rumgay H, Georges D, Huang Y, et al. Global burden of cancer attributable to infections in 2024: a worldwide incidence analysis.Lancet Oncol · 2026 · 27(10):1237-1248doi:10.1016/S1470-2045(26)00307-4 · PMID 42805198

    IARC (the International Agency for Research on Cancer) analysis of GLOBOCAN 2024: 2.3 million infection-attributable cancers, 12% of all cases, across 12 Group 1 agents including S. haematobium, O. viverrini and C. sinensis; largest shares H. pylori 760,000, HPV 750,000, hepatitis B 360,000, Epstein-Barr virus 260,000, hepatitis C 160,000. Parasite-specific counts are in the full text, not the abstract. No external funding declared.

80. 80
    Lamberti O, Ndubani R, Fitzpatrick J, et al. Association Between Female Genital Schistosomiasis and High-Risk Human Papillomavirus Among Women of Reproductive Age in Zambia: The Schista Study.J Infect Dis · 2026 · 234(2):e414-e426doi:10.1093/infdis/jiag153 · PMID 41823984

    2,532 women recruited at home, 1,694 with clinic follow-up; visual FGS 35.2%, molecular FGS 6.5%, high-risk HPV 28.7%; molecular FGS adjusted odds ratio 1.3 (0.9 to 1.9) for any high-risk HPV and 1.7 (1.0 to 2.8) for types 16, 18 and 45; no association for visual FGS. Cross-sectional.

81. 81
    Ngwewondo A, Mbah CE, Sama KO, et al. Molecular, parasitological and clinical diagnosis of female genital schistosomiasis: A diagnostic yield and comparative accuracy study using latent class analysis.Parasitol Res · 2026 · 125(1)doi:10.1007/s00436-026-08753-8 · PMID 42771190

    143 women: PCR positive 73.4%, urine microscopy 29.4%, colposcopy 23.1%; latent-class sensitivity of colposcopy 38.3%, specificity 83.3%. PCR cannot separate active from past infection.

82. 82
    Chen W, Flynn EA, Shreefter MJ, Blagg NA. Schistosomiasis: an unusual finding of the cervix.Obstet Gynecol · 2012 · 119(2 Pt 2):472-475doi:10.1097/AOG.0b013e31822da6a4 · PMID 22270443

    Single case: pale-yellow granular lesions at colposcopy; calcified eggs on histology; urine and stool negative. The abstract does not say which stains the colposcopy used.

83. 83
    Sulżyc-Bielicka V, Kołodziejczyk L, Adamska M, et al. Colorectal cancer and Blastocystis sp. infection.Parasit Vectors · 2021 · 14(1):200doi:10.1186/s13071-021-04681-x · PMID 33853659

    Case-control study: Blastocystis in 12.15% of 107 colorectal cancer patients against 2.42% of 124 controls by iodine-stained smear, nearly matched by PCR. An association the authors read as opportunistic infection, not causation.

84. 84
    Yoon HY, You KH, Kwon JH, et al. Understanding the Social Mechanism of Cancer Misinformation Spread on YouTube and Lessons Learned: Infodemiological Study.J Med Internet Res · 2022 · 24(11):e39571doi:10.2196/39571 · PMID 36374534

    Network study of 702 Korean YouTube videos from 227 channels on taking the dog dewormer fenbendazole for cancer. Shows how antiparasitic cancer claims spread; it does not mention iodine.

85. 85
    Expression of Concern: Real-world Clinical Outcomes of Ivermectin and Mebendazole in Cancer Patients: Results from a Prospective Observational Cohort.Anticancer Res · 2026 · 46(6)doi:10.21873/anticanres.18276 · PMID 42300708

    Editorial notice from the journal on Hulscher et al. 2026: concerns over the verifiability, statistical reliability and ethical oversight of a self-reported 197-patient cohort, with an audit under way. Cited for where the antiparasitic-cancer idea now circulates, not for any result.

86. 86
    Powderly GE, Hassevoort K, Loy M, et al. Drug-Induced Liver Injury Following Co-ingestion of Veterinary Fenbendazole and Ivermectin for Prostate Cancer: A Case Report.Cureus · 2026 · 18(5):e108896doi:10.7759/cureus.108896 · PMID 42299164

    Single case of drug-induced liver injury after three months of alternating veterinary fenbendazole and ivermectin; the authors attribute the self-administration to online cancer support groups.

87. 87
    Saperstein Y, Bou Sanayeh E, Boazak P, et al. Life-threatening neurotoxicity following off-label ivermectin use in metastatic breast cancer: a case report.Postgrad Med · 2026 · 138(4):391-395doi:10.1080/00325481.2026.2672183 · PMID 42170801

    Single case of seizures and respiratory failure after high-dose ivermectin taken on information found online; notes the FDA's discouragement of ivermectin for cancer outside trials.