# The antiparasitic drugs ivermectin and fenbendazole cure cancer, and the medical establishment is hiding it

**Verdict: Contradicted.** No completed, controlled clinical trial has shown that ivermectin (a human and veterinary antiparasitic) or fenbendazole (a dog dewormer never approved for people) treats any human cancer. Both produce interesting signals in a lab dish and in mice at doses far above what a person can safely take, but those signals have never translated into a proven benefit in patients. The origin story, the 2018 remission of businessman Joe Tippens, has a simpler explanation: he was simultaneously enrolled in a clinical trial of the FDA-approved immunotherapy pembrolizumab (Keytruda), the treatment class that can drive exactly that kind of response. In May 2026 the American Society of Clinical Oncology issued a formal notice recommending against using either drug for cancer outside a clinical trial, citing the absence of evidence and real risks including liver toxicity, neurotoxicity, drug interactions, and, most dangerous of all, patients forgoing treatment that works. Rated debunked. This is a record of the evidence, not medical advice.

Category: Science, Space & Technology · Era: 2020s · First circulated: The fenbendazole version dates to Joe Tippens's 2018 blog and the 'Joe Tippens protocol'; the ivermectin version surged post-pandemic, spreading on TikTok, X, and podcasts and accelerating sharply in early 2026 · Believed by: Cancer patients and caregivers drawn to alternative and 'repurposed drug' treatment, amplified by wellness and anti-pharmaceutical communities, short-form video, and high-profile podcast endorsements
URL: https://theconspiratory.com/theory/ivermectin-fenbendazole-cancer-cure

## Summary
After the COVID-19 pandemic turned ivermectin into a political symbol, the antiparasitic found a second life as an alleged cancer cure, joined by fenbendazole, a dewormer sold for dogs. The pitch spread on TikTok, X, and podcasts: a cheap, off-patent drug that big pharma and oncologists supposedly suppress because a lifetime of chemotherapy is more profitable than a cure. The story has a founding anecdote (Oklahoma businessman Joe Tippens, whose late-stage cancer went into remission in 2018) and celebrity fuel (a Mel Gibson claim on Joe Rogan's podcast that ivermectin cured three friends). This case file lays out what is actually known. Both drugs show anticancer activity in cell cultures and animals; neither has been shown to work in people; the Tippens case coincided with an FDA-approved immunotherapy trial; and in May 2026 the American Society of Clinical Oncology recommended against their use outside clinical trials. It separates the real grievances from the claim, and finds the claim debunked. It is not medical advice.

## The claim
That the antiparasitic drugs ivermectin (marketed for humans and livestock) and fenbendazole (a canine dewormer), often combined with vitamin E and curcumin in the 'Joe Tippens protocol', are cheap, effective cures for many cancers; that laboratory and anecdotal evidence proves this; and that pharmaceutical companies, regulators, and oncologists suppress or ignore them because an off-patent cure threatens the profits of conventional cancer treatment.

## Origin and timeline
- 2011–2019: Laboratory researchers publish cell-culture and animal studies reporting that both ivermectin and benzimidazole dewormers (fenbendazole, mebendazole) can slow or kill cancer cells through various mechanisms. This preclinical work is real and openly published, but it involves petri dishes and mice, not proof of benefit in humans, a distinction that later gets lost.
- 2016–2017: Ivermectin's Japanese co-discoverer Satoshi Omura shares in the 2015 Nobel Prize in Medicine for the drug's use against parasitic diseases. The Nobel recognition, for antiparasitic work, is later cited out of context by promoters as if it endorsed the drug against cancer.
- 2018: Oklahoma businessman Joe Tippens, diagnosed with widely metastatic small-cell lung cancer and given a grim prognosis, begins taking fenbendazole, a dog dewormer, on a veterinarian's tip, along with vitamin E and curcumin. He is also enrolled in a clinical trial of the FDA-approved immunotherapy pembrolizumab (Keytruda). His cancer goes into complete remission.
- 2019: Tippens publishes his story on a personal blog, framing the dewormer as the cause of his recovery. The 'Joe Tippens protocol' spreads rapidly through online cancer forums and social media. His concurrent immunotherapy trial, the mainstream explanation for a response like his, is largely absent from the retellings.
- 2020–2021: During the pandemic, ivermectin becomes a political flashpoint after being promoted as a COVID-19 treatment, a use that large randomized trials later fail to support. The controversy leaves the drug with a devoted following primed to distrust regulators, a ready-made audience for the cancer claim.
- 2019–2022: In South Korea, a lung-cancer patient's public embrace of fenbendazole after learning of Tippens sets off a wave of interest, product shortages, and official warnings. Researchers later study how the 'fenbendazole scandal' spread from television and YouTube to desperate patients, a case study in medical misinformation.
- 2025: Preliminary results from the first nine patients in a small phase I/II trial of ivermectin combined with immune-checkpoint inhibitors in metastatic triple-negative breast cancer are presented at the ASCO Annual Meeting. Promoters seize on the existence of a trial as vindication; oncologists note that an early-phase safety study is not proof the approach works.
- January 2026: On Joe Rogan's podcast, actor Mel Gibson says ivermectin and related drugs cured three friends of advanced cancer. Within weeks, online conversation about ivermectin and fenbendazole for cancer jumps by roughly 198 percent, and clinicians report patient interest spreading 'like wildfire'.
- 2026: NPR and other outlets report cancer patients refusing or delaying chemotherapy in favor of the drugs, and several US state legislatures move to make ivermectin available over the counter. Oncologists warn that substitution for proven treatment is the central danger.

## The evidence, claim by claim
- Claim: Laboratory studies prove ivermectin and fenbendazole kill cancer, so the science is already settled.
  Evidence: Cell-dish and animal studies show anticancer activity for many substances that never help a single patient; that is why human trials exist. Both drugs do slow cancer cells in culture and in mice, but often at concentrations or doses far higher than a person can safely reach by mouth. The leap from a petri dish to a cure in people is exactly where the vast majority of promising compounds fail. As of 2026 no completed, controlled clinical trial has shown that either drug treats any human cancer, which is why oncology bodies treat the preclinical work as a reason to study, not a reason to prescribe.
- Claim: Joe Tippens took a dog dewormer and his terminal cancer vanished, which proves fenbendazole cured him.
  Evidence: The founding story has a confounder its retellings usually omit: while taking fenbendazole, Tippens was enrolled in a clinical trial of pembrolizumab (Keytruda), an FDA-approved immunotherapy that can produce durable remissions in a subset of patients, including some with high tumor mutational burden. A dramatic response in someone receiving a checkpoint inhibitor is precisely what that drug is known to do. Crediting the dewormer over the immunotherapy running alongside it is the classic error of assuming that because two things happened together, the wrong one caused the result. A single anecdote with an obvious alternative explanation is not evidence of a cure.
- Claim: These drugs are cheap and off-patent, so there is no money to test them, and industry buries them.
  Evidence: The suppression premise runs against the record. Ivermectin is being tested against cancer right now: a randomized phase II trial (ICONIC) pairing it with immune-checkpoint inhibitors in solid tumors is openly registered on ClinicalTrials.gov, and earlier results were presented at ASCO. Non-commercial researchers, cancer charities, and academic centers with no profit motive would gain enormous prestige from proving a cheap cure works, and would publish it instantly. The drugs are studied openly and discussed openly; what is missing is not the will to test them but positive results in humans. Open investigation is the opposite of a cover-up.
- Claim: They are harmless, so there is no downside to trying them alongside or instead of chemotherapy.
  Evidence: The risks are documented, not hypothetical. Both drugs can cause liver injury; high or repeated ivermectin dosing has caused neurotoxicity, and one reported patient developed confusion, drowsiness, and acute kidney injury after following social-media dosing. Fenbendazole is a veterinary product never tested for safety in humans, and both can interfere with cancer drugs the patient is actually relying on. The gravest harm is the one that leaves no lab trace: patients who delay or refuse effective treatment. In fast-moving cancers, weeks lost to an unproven remedy can be the difference between a curable and an incurable disease.
- Claim: Even oncology's own body is now studying ivermectin, which shows the mainstream is coming around.
  Evidence: It is coming around to the opposite conclusion. In May 2026 the American Society of Clinical Oncology issued a formal clinical notice recommending against the use of ivermectin or fenbendazole to treat cancer, or as an add-on to established therapy, outside a well-designed clinical trial, citing the absence of robust evidence of benefit and the potential for toxicity and harmful interactions. The one in-progress human trial ASCO acknowledged is an early-phase study, the very mechanism by which unproven ideas are tested; its existence is not an endorsement. The professional consensus in 2026 is clearer than ever: not proven, and not recommended.

## Why people believe it
- A cancer diagnosis is terrifying, and standard treatment can be harsh, slow, and uncertain. A cheap pill that promises to work gently offers hope and a sense of control, and the idea that it is being withheld gives the fear and anger somewhere to go. That is a deeply human response, not a foolish one.
- The pandemic did lasting damage to trust. Ivermectin became a symbol of a fight over who to believe about medicine, and for many the cancer claim arrived already wrapped in a story of experts who supposedly lie and a cheap drug they supposedly fear. The distrust was pre-loaded before the first tumor was mentioned.
- The preclinical studies are real, which makes the claim feel grounded rather than invented. Promoters can point to genuine, published papers showing the drugs killing cancer cells, and it takes a further step, one many people never hear, to learn that a signal in a dish or a mouse almost never carries over to patients.
- The 'cheap suppressed cure' narrative is morally clean and easy to hold: an off-patent drug big pharma cannot profit from, buried to protect chemotherapy revenue, with clear villains and a clear victim. It is far more satisfying than the real picture of hundreds of different diseases yielding slowly to incremental work.
- Anecdote and survivorship bias do the rest. A patient who took the drugs and lived, very often while also receiving real treatment, becomes a vivid, shareable testimonial; the people who took them instead of treatment and died are not there to tell their side, so the visible evidence is skewed toward apparent success.

## Open questions
- Whether ivermectin has any genuine adjuvant role alongside immunotherapy is a real scientific question, which is why the randomized ICONIC trial exists. An honest skeptic waits for that result rather than assuming the answer; a negative trial would settle it, and a positive one would change practice through evidence, not testimonials.
- Drug repurposing is a legitimate field: some old, cheap drugs have found new uses. The possibility that a repurposed antiparasitic could help in some narrow setting is not absurd on its face; what is absurd is treating that open possibility as if it were already an established, suppressed cure for cancer generally.
- The distrust powering the belief points at real failures worth addressing on their own terms: pandemic-era communication that overreached, drug prices that ruin families, and an industry with a documented history of dishonesty. Those grievances are genuine; they are simply not evidence that these particular drugs cure cancer.
- The regulatory question raised by states moving ivermectin over the counter is live and separate from efficacy: easier access raises the risk of self-medication and treatment substitution, a consumer-safety issue distinct from whether the drug works against tumors.

## Latest developments
- 2026-05-01T12:00Z: The American Society of Clinical Oncology issued a formal clinical notice recommending against the use of ivermectin and fenbendazole to treat cancer, or as an adjunct to established therapy, outside a well-designed clinical trial, citing the absence of robust peer-reviewed evidence of benefit and the potential for toxicity and harmful drug interactions. ASCO also urged oncologists to raise the subject proactively and non-judgmentally with patients. (source: https://connection.asco.org/do/asco-clinical-notice-recommending-against-ivermectin-and-fenbendazole-cancer-treatment)

## Sources
- ASCO Clinical Notice: Recommending Against Ivermectin and Fenbendazole for Cancer Treatment, Outside of Clinical Trials, American Society of Clinical Oncology (ASCO Connection) (2026): https://connection.asco.org/do/asco-clinical-notice-recommending-against-ivermectin-and-fenbendazole-cancer-treatment
- Oncologists Urged to Take Proactive Approach When Discussing Ivermectin, Fenbendazole, American Society of Clinical Oncology (ASCO) (2026): https://www.asco.org/news-initiatives/policy-news-analysis/oncologists-urged-proactive-approach-discussing-ivermectin-fenbendazole
- What to Know About Ivermectin, American Cancer Society: https://www.cancer.org/cancer/latest-news/what-to-know-about-ivermectin.html
- What to Know About Fenbendazole, American Cancer Society: https://www.cancer.org/cancer/latest-news/what-to-know-about-fenbendazole.html
- Ivermectin is making a post-pandemic comeback, among cancer patients, NPR (2026): https://www.npr.org/2026/03/02/nx-s1-5729102/ivermectin-politics-treatment-cancer-evidence
- Ivermectin isn't a cancer miracle drug, but influencers claim otherwise: here's how to avoid sprinting past scientific evidence, The Conversation (2026): https://theconversation.com/ivermectin-isnt-a-cancer-miracle-drug-but-influencers-claim-otherwise-heres-how-to-avoid-sprinting-past-scientific-evidence-286337
- Ivermectin Combined With Immune Checkpoint Inhibition in Cancer (ICONIC), ClinicalTrials.gov, U.S. National Library of Medicine: https://clinicaltrials.gov/study/NCT07487805
- A single institutional experience on patterns of ivermectin and fenbendazole use among patients with gastrointestinal cancers, Journal of Clinical Oncology (ASCO) (2026): https://ascopubs.org/doi/10.1200/JCO.2026.44.2_suppl.818
- How cancer patients get fake cancer information: from TV to YouTube, a qualitative study focusing on the fenbendazole scandal, BMC / PubMed Central (2022): https://pmc.ncbi.nlm.nih.gov/articles/PMC9650234/

Rated by The Conspiratory, a neutral, sourced encyclopedia of conspiracy theories. Full page: https://theconspiratory.com/theory/ivermectin-fenbendazole-cancer-cure