Something changed quietly in American oncology clinics early in 2025. Doctors who had spent years guiding patients through chemotherapy schedules and radiation plans suddenly found themselves fielding questions about a livestock dewormer and an antiparasitic drug most of them hadn’t discussed with a human patient in years. The questions kept coming, from patients with early-stage diagnoses, from patients in the middle of treatment, from patients whose families were searching for anything that might help. Nobody had sent out a press release. There had been no medical conference, no new clinical trial result. Something else had happened.
The story of how a two-hour podcast conversation rippled through the American healthcare system and changed prescribing behavior across the country is not simply a cautionary tale about celebrity influence. It is a window into how deeply fractured the relationship between patients and medical institutions has become, and what that fracture means when life-or-death decisions are on the line.
The numbers that eventually emerged from this episode are striking enough on their own. But the more important story is what drove ordinary people with serious diagnoses to act on an anecdote, and what that tells us about the state of medical trust in 2025.
A Podcast Moment That Moved Prescriptions Nationwide
On January 9, 2025, actor Mel Gibson appeared on The Joe Rogan Experience and described three friends with stage IV cancer who he said recovered after taking ivermectin and fenbendazole. The exchange was brief and anecdotal. No clinical data, no verified medical records, no independent corroboration. Gibson said, “I have three friends. All three of them had stage four cancer… All three of them don’t have cancer right now, at all.”
The episode gathered tens of millions of views within the first month, and prescribing rates for both medications moved sharply upward. Excerpts of the interview went viral on Facebook, Instagram, TikTok, and X (formerly Twitter). The Canadian Cancer Society was among the institutions that responded publicly, posting on X: “Mel Gibson promoted drugs that are not scientifically proven cancer treatments. Misinformation on cancer treatment is dangerous, cruel, irresponsible and gives false hope to people with cancer and their loved ones.”
The researchers who later studied the prescribing surge wrote that celebrity influence “gains traction when institutional trust erodes.” Ivermectin had already become a politically charged drug during the COVID-19 pandemic, and both ivermectin and fenbendazole had circulated in online communities for years as purported alternative therapies. Gibson’s appearance did not create the idea from nothing. It amplified one that was already present, and it did so at extraordinary scale.
During Joe Rogan’s podcast on January 9, Mel Gibson promoted drugs that are not scientifically proven cancer treatments. Misinformation on cancer treatment is dangerous, cruel, irresponsible and gives false hope to people with cancer and their loved ones.
— Canadian Cancer Society (@cancersociety) January 10, 2025
Researchers around the…
The Study: 68 Million Patient Records, One Podcast
Researchers from UCLA Health undertook what became the most comprehensive analysis of this prescribing shift to date. Published in JAMA Network Open on May 12, 2026, the study compared prescription patterns for the combination of ivermectin and benzimidazole drugs among people with and without cancer from January 1 through July 31, 2025, following the endorsement, against the corresponding period the year before. Researchers used de-identified electronic health records from more than 68 million patients across the multicenter US TriNetX research network, capturing prescriptions issued to patients aged 18 to 90 in ambulatory care and emergency departments.
The scale of that dataset matters enormously. This was not a regional sample or a snapshot from a handful of hospitals. It was a cross-section of the American healthcare system, drawing on records from 67 health systems before and after the podcast aired.
The study found that overall prescribing rates across the entire cohort doubled during the months following the endorsement compared with the same period the year before. Among people with cancer, prescribing rates were more than 2.5 times higher during the more recent period. In the US South, those rates were more than three times higher than in the corresponding six months the previous year. Ivermectin prescriptions alone leapt by 97% in the United States in the six months following Gibson’s appearance on the podcast.
Who Was Most Affected
The demographic breakdown is one of the more analytically significant parts of the study. White patients, men, and people living in the South were most likely to have an ivermectin-benzimidazole prescription, according to the research. That geographic and demographic concentration does not appear to be random. The study’s authors noted that it effectively provides public health authorities with a map of where trusted medical messengers are most urgently needed.
Senior researcher Dr. John Mafi, an associate professor-in-residence of medicine at UCLA, said: “When prescribing for an unproven cancer treatment more than doubles after a single podcast, especially among men and people in the South, it raises a concern that patients may be skipping or delaying treatments we know work in favor of something that hasn’t been proven to help them.”
Co-author Dr. Katherine Kahn, a professor of medicine at the David Geffen School of Medicine at UCLA, emphasized that “not all widely shared health information is accurate, even when it comes from familiar or influential sources.”
What the Science Actually Shows About These Drugs
Understanding why researchers are concerned requires a clear view of what ivermectin and fenbendazole actually are, and what the evidence does and does not support.
Ivermectin
Ivermectin, the development of which won two researchers part of the 2015 Nobel Prize in Physiology or Medicine, is well proven for its safety and effectiveness in treating diseases caused by parasitic worms. The FDA has approved the ivermectin tablet to treat people with specific roundworm infections and river blindness. The topical version is approved for external parasites such as head lice and rosacea. Those are its legitimate, established uses.
The question of whether it has any role in cancer treatment is a different matter. Animal studies suggest ivermectin and benzimidazole drugs, a class that includes fenbendazole, may have certain properties that could inhibit tumor growth, but this use is unproven in humans. No large-scale randomized controlled trials have shown ivermectin to be effective against cancer.
The most recent human data is not encouraging. A phase 1/2 study of ivermectin in combination with immunotherapy for patients with metastatic triple-negative breast cancer, presented at the 2025 American Society of Clinical Oncology Annual Meeting, showed no real benefit. Of eight evaluable patients, one had stable disease, six had disease progression, and one had a partial response, which is the result one would expect from immunotherapy alone.
Fenbendazole
Fenbendazole occupies an even murkier regulatory position. The FDA has never approved fenbendazole for humans for any purpose. Scientific data about whether fenbendazole is safe and effective for people simply does not exist. It has no approved human dose, no standardized formulation, and no monitoring framework, with product quality varying widely across veterinary and supplement sources.
Personal “success” stories can sound compelling, but they don’t prove fenbendazole is a safe and effective cancer treatment. Many of the anecdotal cases researchers have examined involved patients who were simultaneously receiving established cancer therapies such as immunotherapy, making it impossible to attribute any observed response to the antiparasitic drug alone.
The Dosing Problem
One of the most pressing safety concerns involves the dose required to even theoretically replicate the anti-tumor effects seen in laboratory settings. According to Dr. Skyler B. Johnson of the University of Utah Huntsman Cancer Institute, the pre-clinical studies of ivermectin are almost all done “in petri dishes and mice,” and “the challenge is that the doses used in mice would likely be toxic to be effective in humans.”
Real-world case reports have already documented serious harm. According to Pharmacy Times, a patient with osteosarcoma took 12 mg of ivermectin three times over five days based on social media guidance while also taking regorafenib, and presented with anorexia, nausea, fatigue, near-syncope, drowsiness, and acute kidney injury, ultimately determined to be ivermectin-related neurotoxicity. Dr. Johnson also expressed concern about how ivermectin might affect the way the body processes cancer treatments and other medications.
The Limits of the Study, and Why They Matter
The researchers are careful to note that their work has meaningful limitations, and those caveats matter for any honest reading of the findings.
The study’s observational design cannot establish cause and effect. As a convenience sample, it may not be fully representative of the United States as a whole. It focused on physician orders rather than actual drug use, meaning it cannot confirm whether patients filled their prescriptions or took the medications. Whether patients were using these drugs alongside standard cancer treatments, or instead of them, also remains unclear.
Agricultural retailers sell ivermectin formulations for livestock, and some patients may have obtained the drug without a prescription at all, meaning the true scale of use could be larger than the prescribing data suggests.
Still, the prescribing data alone is striking enough to demand serious attention. Lead researcher Dr. Michelle Rockwell, an assistant professor of family and community medicine at the Virginia Tech Carilion School of Medicine, noted: “These findings remind us that some forces can influence care very quickly. The challenge for health systems is how to meet patients in that moment with information that is both timely and trustworthy.”
Celebrity Influence in Medicine: A Double-Edged Reality
The researchers did not conclude their analysis with alarm alone. They were also careful to note that celebrity influence on health behavior is not inherently negative, and that the current moment may represent an opportunity as much as a warning.
Dr. Rockwell pointed to a well-documented historical example: after TV journalist Katie Couric had a colonoscopy on the Today Show in 2000, the nationwide rate of colorectal cancer screening increased by 20%. That rise in screening, documented by researchers at the University of Michigan and the University of Iowa, was dubbed the “Katie Couric Effect,” and screening rates persisted at up to 20% higher than normal across the US for at least nine months after the episode aired. The lesson was that a single media moment, with the right person delivering an evidence-based message, can produce population-level health gains that last.
The difference, in this case, is evidence. Couric was promoting a life-saving screening tool with established clinical value. The Gibson conversation promoted an anecdote involving drugs that have not been validated for cancer treatment in humans.
Read More: Alabama Teen Gets Experimental Cancer Drug After Viral Plea
The lesson for public health is not to retreat from popular media platforms, but to compete for presence on them. As the study authors noted, the clinical encounter alone may not be a sufficient intervention point, because by the time a patient is sitting in a doctor’s office asking about ivermectin, they have often already been exposed to the claim dozens of times across multiple platforms. That repeated exposure shapes conviction in ways a single conversation rarely undoes.
The demographic patterns revealed in the study hand public health a practical map of where trusted messengers are most needed. That concentration of the prescribing spike among men, white patients, and residents of the South tells public health researchers exactly where to direct evidence-based outreach.
What This All Means
If you or someone you love is living with a cancer diagnosis, the most direct takeaway from this research is straightforward: the fact that a drug is widely discussed online does not mean it has been tested in humans, and the fact that it has shown effects in laboratory cells or animal models does not mean those effects will translate safely or effectively to the human body. Laboratory studies of fenbendazole and other antiparasitic drugs have shown some early promise, but results in a petri dish or in animal models don’t reliably predict what happens in people. The American Cancer Society and the National Institutes of Health’s National Center for Complementary and Integrative Health both counsel patients to discuss any non-standard treatment with their oncology team before starting it, and to be especially cautious about substituting unproven therapies for treatments with established clinical benefit.
Dr. Johnson put it plainly: “We know that many patients feel like they can’t be open and honest with their physician out of fear of judgment. We want open lines of communication with our patients.” That openness is the critical first step. Patients who are curious about these drugs are best served by bringing the question directly to their care team, where the full context of their treatment plan, their specific cancer type, and any potential drug interactions can all be taken into account.
For clinicians and health systems, the study points to a structural challenge that predates this episode entirely. Interest in alternative therapies in cancer care is at an all-time high, often driven by misinformation, distrust of conventional medicine, and a feeling that patients have lost control over their own care. Addressing that dynamic requires more than faster fact-checks. It requires rebuilding the conditions under which patients feel their doctors are giving them complete and honest information, not just about what has been approved, but about the questions they are already asking.
The National Cancer Institute launched a preclinical study in early 2026 to investigate ivermectin’s potential against cancer. Preclinical means the research is still in the early phase, not yet tested in large-scale human clinical trials. If that research eventually yields results worth pursuing further, formal clinical trials will be the appropriate setting in which to evaluate these drugs. Not a podcast segment, and not a social media thread, but a rigorous trial designed to tell us, with real certainty, whether the treatment works and whether it is safe.
AI Disclaimer: This article was created with the assistance of AI tools and reviewed by a human editor.
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