Fenbendazole is a benzimidazole dewormer approved in the United States since 1979 for dogs (Panacur C) and used in many other animals.
Amounts reported for Fenbendazole are listed under Reported protocols, each with its source and study kind. No amount ladder is inferred from them. This is educational source context, not a protocol or recommendation.
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Human study rows are described per source under Reported protocols; they belong to their trial populations and are not a general amount.
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What published studies and recent community write-ups report about amounts, timing and course length. 2 clinical, 2 preclinical and 2 community-reported rows, each linked to its source. These are descriptions of what others report, not instructions, and nothing here is medical advice.
| Context | Dose | Frequency | Route | Course | Source |
|---|---|---|---|---|---|
| Clinical2 rows | |||||
| Approved veterinary label (Panacur C canine dewormer)Dogs and puppies from 6 weeks of age, including pregnant bitches | 50 mg/kg (22.7 mg/lb) of body weight; the 1 g packet contains 222 mg of fenbendazole | Once daily, mixed into a small amount of food | Oral granules (22.2%) | 3 consecutive days per dewormingAdult dogs dewormed at least twice a year; puppies at 6, 8, 10 and 12 weeks | DailyMed, National Library of Medicine2026 |
| This is an FDA-approved animal drug label (NADA 121-473), included because it is the only regulator-reviewed dosing for fenbendazole and because the 222 mg figure used in community cancer protocols is simply the content of the smallest packet. In US clinical studies about 1% of 240 treated dogs vomited. Nothing on the label concerns people or cancer. | |||||
| Drug-induced liver injury after self-dosing (case report)A 65-year-old man with prostate cancer taking veterinary fenbendazole and ivermectin on the advice of online cancer groups | About 0.98 mg/kg of fenbendazole per dose, estimated from the 'one squirt' of veterinary paste he used | Alternating daily with ivermectin (about 0.18 mg/kg) | Oral veterinary paste | 3 months before presentationNot applicable | Cureus (PubMed)2026 |
| He presented with two weeks of fatigue, jaundice and abdominal pain, ALT 1,764 U/L, AST 1,132 U/L and bilirubin 12.9 mg/dL, and a RUCAM score of 9 rated the anthelmintics as the highly probable cause; enzymes fell 58% within nine days of stopping and normalised by six weeks. Two other reports describe the same pattern: an 80-year-old woman with lung cancer on pembrolizumab whose severe liver injury resolved after she stopped a month of fenbendazole (2021), and a 47-year-old woman with metastatic colon cancer on nivolumab and relatlimab whose hepatocellular injury followed an increase in her self-chosen dose (2026). None of the three patients had tumour shrinkage attributed to the drug. | |||||
| Preclinical2 rows | |||||
| Human lung cancer xenografts in miceFemale athymic nude mice bearing A549 human lung adenocarcinoma xenografts 2-3 mm across | 1 mg per mouse, dissolved in olive oil | Every second day | Oral | 12 daysAlternate-day dosing | Scientific Reports (PubMed Central)2018 |
| Oral fenbendazole reduced tumour size and weight compared with olive oil alone, and in cell culture the drug destabilised microtubules at micromolar concentrations, moved p53 to mitochondria and cut glucose uptake, GLUT transporter expression and hexokinase II. One milligram in a roughly 25 g mouse is about 40 mg/kg, far above anything a person could absorb from a 222 mg capsule, and the result has not been reproduced in people. | |||||
| Mouse mammary tumours with and without radiationMice carrying EMT6 mammary tumours | 50 mg/kg per day | Three daily injections | Intraperitoneal | 3 days, alone or before 10 Gy of local x-raysNot applicable | Anticancer Research (PubMed Central)2013 |
| Intensive fenbendazole was toxic to EMT6 cells in culture, especially under severe hypoxia, but in the animals it neither slowed tumour growth nor increased the effect of radiation or docetaxel beyond additive cytotoxicity. The Yale authors concluded that the studies provided no evidence that fenbendazole would have value in cancer therapy, a negative result that community guides rarely mention. | |||||
| Community-reported2 rows | |||||
| Community cancer protocols (Tippens pattern and escalations) | 222 mg (one 1 g Panacur C packet or one capsule); 444 mg and 500-1,000 mg described as higher tiers | 3 days a week (Tippens), 6 days a week, or daily in the higher tiers | Oral, taken with a fatty meal for absorption | Open-ended; some versions run continuously for years4 days off each week in the original pattern; 1 day off in the 6-day version | Community resource2026 |
| This March 2026 guide lays out four tiers from 222 mg three times a week with curcumin 600 mg, vitamin E succinate 800 IU and CBD 25 mg a day, through 444 mg daily with milk thistle, to 500-1,000 mg daily, and a separate set of tiers that add ivermectin at 0.2-2.5 mg/kg. It states that no completed human trial exists, rates liver toxicity risk as moderate, and tells readers to get liver tests every 4-6 weeks and to disclose use to their oncologist. Every number is community-derived and the page carries affiliate links to the supplements it names. | |||||
| Vendor capsule format | 222 mg per capsule, 60 capsules per bottle (13,320 mg total); no dose stated | Not stated | Oral | Not statedNot stated | Community resource2026 |
| A vendor claim. The capsule strength copies the fenbendazole content of a 1 g Panacur C packet, which is how the Tippens figure entered circulation; the product page frames the compound as benzimidazole and microtubule research and the certificate for lot FB01 confirms identity by mass spectrometry without a measured content. The vendor's own disclaimer excludes oncology, antiparasitic and oral use. | |||||
The only regulator-reviewed course is three consecutive daily doses of 50 mg/kg in dogs, mixed with food, repeated a few times a year. There is no human label and no human course of any length.
The Tippens pattern is 222 mg with a fatty meal on three consecutive days followed by four days off, usually alongside curcumin, vitamin E succinate and CBD. Later variants run six days on and one off, or double the dose; none has been tested in a trial.
Community guides advise liver tests every four to six weeks because the published harm signal is hepatitis: in the case reports, liver enzymes rose within one to three months of self-dosing and fell within days to weeks of stopping. One patient reached an ALT of 1,764 U/L and a bilirubin of 12.9 mg/dL before anyone connected it to the dewormer.
Plus 2 community resources (dosing guides, forum threads and vendor write-ups), reported above but not linked.
Fenbendazole is a benzimidazole dewormer approved in the United States since 1979 for dogs (Panacur C) and used in many other animals; it has never been approved for people, who are treated with the related drugs mebendazole and albendazole. Interest in cancer dates from a 2018 report that it destabilises microtubules, cuts glucose uptake and shrinks human lung tumour xenografts in mice, and from the online account of Joe Tippens, who credited 222 mg three days a week for his remission while also receiving pembrolizumab in a trial. There is no completed human trial, a 2013 mouse study found no effect on tumour growth, and case reports since 2021 describe serious drug-induced liver injury in cancer patients who dosed themselves on the strength of social media; the 222 mg capsule sold here mirrors the fenbendazole content of a 1 g Panacur C packet.
These themes describe recurring questions in published research. They are not claims of effectiveness or recommendations for use.
Cell-cycle, repurposed-compound and tumour-model research.
This is an FDA-approved animal drug label (NADA 121-473), included because it is the only regulator-reviewed dosing for fenbendazole and because the 222 mg figure used in community cancer protocols is simply the.
Oral fenbendazole reduced tumour size and weight compared with olive oil alone, and in cell culture the drug destabilised microtubules at micromolar concentrations, moved p53 to mitochondria and cut glucose uptake.
Intensive fenbendazole was toxic to EMT6 cells in culture, especially under severe hypoxia, but in the animals it neither slowed tumour growth nor increased the effect of radiation or docetaxel beyond additive.
He presented with two weeks of fatigue, jaundice and abdominal pain, ALT 1,764 U/L, AST 1,132 U/L and bilirubin 12.9 mg/dL, and a RUCAM score of 9 rated the anthelmintics as the highly probable cause; enzymes fell 58%.
This March 2026 guide lays out four tiers from 222 mg three times a week with curcumin 600 mg, vitamin E succinate 800 IU and CBD 25 mg a day, through 444 mg daily with milk thistle, to 500-1,000 mg daily, and a.
Study models remain visible so laboratory and animal findings are not mistaken for established human outcomes.
2 protocol rows on this page come from human trials, trial registrations, regulator labels or reviews of human data. Approval status and populations are stated per row.
2 protocol rows describe animal, cell or toxicology work. Amounts from these rows do not translate to people.
2 rows record what blogs, vendor write-ups or forums describe for Fenbendazole. None has been verified against primary literature.
Sequence, synonyms and registry identifiers as recorded in PubChem, the National Library of Medicine's open chemistry database. Formula, mass and CAS number are summarized at the top of the page.
Panacur, Safe-Guard, Fenbendazol, Hoe 881v, Methyl 5-(phenylthio)-2-benzimidazolecarbamate, UNII 621BVT9M36, Fenbendazolum
HDDSHPAODJUKPD-UHFFFAOYSA-N
methyl N-(6-phenylsulfanyl-1H-benzimidazol-2-yl)carbamate
8 curated references, each with its journal, year and study model, plus 2 community resources reported but not linked.