Prescriptions for controversial anti-worming drug ivermectin have surged in the last year after Mel Gibson claimed it cured his friends’ cancer.
Gibson, 70, told podcaster Joe Rogan last year that three of his friends with stage four cancer were cured after taking ivermectin and fenbendazole, drugs that that parasitic infections in people and livestock.
The Lethal Weapon star sensationally claimed all three friends ‘don’t have cancer right now,’ adding, ‘This stuff works, man.’
Clips of the podcast segment were viewed tens of millions of times. Now, researchers at the University of California – Los Angeles (UCLA) fear the claims may have caused irreparable damage.
The researchers found in just one year, prescriptions for ivermectin doubled compared to the previous one-year period.
Among people with cancer, rates jumped 2.5 times. And prescriptions in the south skyrocketed three-fold in 2025 compared to the year before, with men statistically more likely to reach for the drug.
The researchers caution that while ivermectin has been shown to have anti-cancer benefits in some studies on laboratory cells and animals, no clinical trials have shown it is safe in people with cancer.
Ivermectin is also dosed by body weight, and formulas intended for livestock have much higher concentrations of the drug than formulations FDA-approved for humans, making is easy to accidentally overdose.
Actor Mel Gibson in 2025 claimed to Joe Rogan that three of his friends with stage four cancer allegedly cured their disease with anti-parasitic drugs ivermectin and fenbendazole
‘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,’ Dr John N Mafi, senior study author and associate professor-in-residence of medicine at the David Geffen School 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.’
In the new study, published in JAMA Network Open, researchers looked through data from 67 health care organizations across the US to identify ivermectin prescriptions for patients ages 18 to 90 from 2018 to 2025.
Out of a total of 68.3 million patients, the team found that ivermectin prescriptions doubled from the time period of January 1, 2025 to July 31, 2025, compared to the same time period the year before.
Prescriptions among white patients rose 2.6 times compared to people of other races, there was a 3-fold increase in prescriptions among patients in the south. Among men, prescriptions surged 2.8-fold.
And among cancer patients, prescriptions increased 2.5 times.
‘We often focus on how to efficiently get evidence into practice,’ Dr Michelle Rockwell, lead study author and assistant professor of family and community medicine at Virginia Tech, said.
‘But 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.’
Ivermectin gained popularity during the pandemic after fringe medical figures, some now in federal roles, promoted it as a Covid remedy with no clinical proof. Since then, right-leaning influencers have touted it as a dubious cure for various other conditions
Ivermectin was first approved for animal use in 1981, though it would be three decades before it became touted as a potential cancer treatment.
The earliest research dates back to 2014, with a Swiss study suggesting ivermectin could stop the growth of some lung and colon tumors. However, the study was performed on cells rather than human subjects.
Dr Peter P Lee, study author and chair of the immuno-oncology department at City of Hope, said at the time: ‘Certainly by itself ivermectin is not a cure or even an effective treatment for breast cancer.
‘I pride myself as a rigorous, fair-minded scientist. And in our hands, through many years of experiments, it has promise — but not by itself.’
A 2021 study from researchers at City of Hope Comprehensive Cancer Center in California suggested using ivermectin alongside the antibody anti-PD1 could treat triple-negative breast cancer tumors in mice.
However, the researchers cautioned that it’s unclear if the same results can be replicated in humans and advised against taking ivermectin on its own.
Ivermectin has also been shown to be largely ineffective against Covid.
It became a political hot button issue during the pandemic after Republican politicians, including President-Elect Donald Trump, voiced their support for the drug’s use against Covid.
The study found prescriptions for ivermectin doubled in 2025 compared to the year before, which researchers believe may be due to Gibson’s endorsement of the drug for cancer
In 2022, the National Institutes of Health (NIH) wrote on its website that it ‘recommends against the use of ivermectin for the treatment of COVID-19, except in clinical trials.’
Ivermectin can cause dangerous and even dreadful side effects when misused or taken without medical supervision. These include neurotoxicity, such as seizures, coma and altered consciousness, as well as liver and kidney damage, severe skin reactions and life-threatening drug interactions.
The drug also has been shown to interact with the blood thinner warfarin, as ivermectin can disrupt clotting factors, leading to increased bleeding.
‘Not all widely shared health information is accurate, even when it comes from familiar or influential sources,’ Dr Katherine Kahn, study author and Distinguished Professor of Medicine at the Geffen School, said.
‘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.’
