It’s official: Ivermectin has gotten the Mel Gibson bump. Research out today shows how the popularity of the antiparasitic drug skyrocketed after the controversial celebrity touted its dubious benefits against cancer on Joe Rogan’s podcast early last year.
Scientists tracked prescription trends in the aftermath of Gibson’s appearance on The Joe Rogan Experience, during which he claimed a combination of ivermectin and fenbendazole had saved his friends from advanced cancer. Compared to the previous year, total prescriptions of the drugs doubled in the six months following the episode, they found. Importantly, however, there’s little reason to believe these drugs work as advertised against cancer, the researchers note.
“Our findings extend prior work on the potential influence of celebrity endorsement on health care utilization,” they wrote in their paper, published Tuesday in the journal JAMA Network Open. “Such influence gains traction when institutional trust erodes.”
Not a cancer cure-all
Ivermectin is a cheap, effective, and widely used antiparasitic. In recent years, however, it’s taken on another life as a miracle treatment for everything under the Sun among certain circles. These people tend to be right-wing and/or generally skeptical of mainstream medicine, particularly vaccines. One such fan is Robert F. Kennedy Jr., the current head of the U.S. Department of Health and Human Services.
Early on in the pandemic, ivermectin was tested as a potential treatment for the viral disease, based on some encouraging lab studies. Subsequent research largely failed to find any benefit from ivermectin, while positive studies were often flagged for glaring flaws or potential fraud.
In the wake of these failures, however, some people have continued to claim that ivermectin can not only treat many viral diseases but cancer as well. And under RFK Jr.’s tenure, the National Cancer Institute announced earlier this year that it would begin to study ivermectin’s anticancer effects. It was a decision that alarmed experts outside and even inside the agency. While some studies in the lab and with animals have possibly suggested ivermectin can kill cancer cells, no large-scale randomized and controlled trials of actual humans have shown it to be useful against cancer.
That didn’t stop Gibson from praising ivermectin on the January 9, 2025, episode of The Joe Rogan Experience. Gibson claimed that three of his friends with Stage IV cancer recovered after taking a combination of ivermectin and fenbendazole, another commonly used deworming treatment (as with ivermectin, no strong evidence supports its use for cancer). According to the study’s researchers, the podcast episode was viewed by more than 60 million people.
The researchers analyzed medical records from 68 million adult patients in the U.S. TriNetX research network, a database covering over 60 healthcare organizations across the country. They specifically looked for outpatient and emergency room prescriptions of ivermectin in combination with fenbendazole. John N. Mafi, an associate professor-in-residence of medicine, division of general internal medicine and health services research at the David Geffen School of Medicine at UCLA, is the senior author on the study.
From January 2025 to July 2025, the researchers found, overall prescription rates of the two-drug combo doubled relative to the same time period in 2024. The rate increased even higher among patients with diagnosed cancer (more than 2.5 times higher) and among patients living in the U.S. South (threefold higher).
Celebrity woo
Ivermectin isn’t an especially dangerous drug, though it can cause potentially serious side effects if taken in larger-than-usual doses. Another worrying risk is that some cancer patients will choose to take it over other proven interventions—a well-known phenomenon seen with other treatments outside of the mainstream. A study earlier this March found that breast cancer patients who admitted to taking complementary and alternative treatments were more likely to die over a five-year span compared to others on traditional treatment.
“The elevated prescribing observed among patients with cancer is particularly concerning; individuals facing life-threatening illness may delay or forgo conventional treatments in favor of unproven therapies, potentially allowing their disease to progress,” the current study researchers wrote.
Ivermectin is great against parasites. But it’s unlikely to be a genuine cancer killer, no matter how many celebrities believe otherwise.
