In January 2025, during an appearance on the high-profile podcast The Joe Rogan Experience, Mel Gibson insisted that three of his friends had recovered from Stage IV cancer by taking ivermectin, an antiparasitic medication used to treat tropical diseases, and fenbendazole, which is approved only for veterinary use. Despite a lack of scientific evidence to support Gibson’s anticancer claim, prescriptions for ivermectin more than doubled in the months following the Braveheart director’s endorsement, according to researchers at the University of California, Los Angeles who studied the aftermath of this incident and published their findings in JAMA Network Open.
Data show that celebrities often influence the public when it comes to health information and habits. But people were not equally swayed. More specifically, the researchers found that the ivermectin prescription jump was more prominent among white patients, men, people living in the South and those with cancer.
“As a primary care doctor, I want my patients and people across the country to have the chance to get treatments we know can help them live longer, healthier lives,” said senior study author John N. Mafi, MD, MPH, in a UCLA press release on the study.
Mafi, an associate professor-in-residence of medicine at the David Geffen School of Medicine at UCLA, continued: “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.”
The scientists who discovered ivermectin, which is effective in treating conditions caused by parasitic worms in humans and animals, received a Nobel Prize in 2015. The Food and Drug Administration (FDA) has approved the oral version of the drug for use in humans only as an antiparasitic. As a lotion, the drug is also approved to treat lice and rosacea.
In recent years, ivermectin developed a controversial reputation as the miracle drug at the center of claims by conservatives and members of the Make America Healthy Again movement. During the COVID-19 pandemic, ivermectin surged in popularity when it was inaccurately promoted as an effective treatment for SARS-CoV-2, the virus that causes COVID. Clinical trials have since proved the drug isn’t effective against COVID-19.
Some work on cells and in animal studies suggests ivermectin and benzimidazole drugs, like fenbendazole, may promote anticancer activity. However, none of this research has been replicated in studies on humans, and no clinical trial has confirmed the drug’s safety or efficacy as a cancer treatment. Although the National Cancer Institute announced it would study ivermectin as a treatment for cancer, there seems to be insufficient evidence to warrant using taxpayer funds to investigate the drug.
The FDA has not approved fenbendazole for any use in humans; it remains a veterinary med for deworming animals.
As NPR pointed out in an article in March, despite the lack of rigorous data supporting ivermectin for off-label use, many people, notably conservatives, look to it as a miracle drug. NPR’s Yuki Noguchi wrote:
“Ivermectin is now making a comeback, after its use receded in the waning years of the pandemic. Now, especially in conservative political circles, its reputation keeps growing as a kind of cure-all for various ailments, and even for cancer—despite a lack of evidence it works.
So far, five state legislatures—in Tennessee, Arkansas, Idaho, Louisiana and Texas—have voted to make the drug available over-the-counter, causing concern among doctors who say people might overuse or misuse it, or worse—substitute ivermectin for proven treatments.”
For the study on the prescription spike following Gibson’s podcast appearance, researchers from UCLA, University of Michigan and Virginia Tech used electronic health records from 67 health care organizations nationwide to track prescriptions for ivermectin-benzimidazole from 2018 to mid-2025 for people with and without cancer diagnoses. They also used census data to track demographic information on people being prescribed ivermectin.
Among over 68 million patients, ivermectin-benzimidazole prescription rates were twice as high for the first six months of 2025 compared with the first six months of the prior year. Among people with cancer, the prescription rate for the first six months of 2025 was 2.5 higher than the year before. For people living in the South, the rate was three times higher in the first six months of 2025 than the previous year.
The researchers cannot conclude whether the increase in ivermectin prescriptions was primarily due to Gibson’s endorsement. They also cannot say whether the prescriptions were filled or used by patients or whether the drug replaced or supplemented ongoing cancer treatment.
At the time of the study’s publication, the episode of The Joe Rogan Experience in question had been viewed by over 60 million people across multiple platforms.
“Not all widely shared health information is accurate, even when it comes from familiar or influential sources,” said study author Katherine Kahn, MD, a professor at the Geffen School of Medicine and member of the UCLA Health Jonsson Comprehensive Cancer Center. “Using unproven treatments can carry real risks, especially if it delays care that is known to work. Clinicians and health systems play a critical role in helping patients navigate information and make informed decisions.”
