Prescriptions for ivermectin and another antiparasitic drug among cancer patients shot up after actor Mel Gibson discussed an unproven treatment on Joe Rogan’s popular podcast, according to a study published today in JAMA Network Open.
Researchers say these findings raise concerns about the potency of celebrity endorsement, which can encourage people with life-threatening illnesses to delay or forgo conventional care that’s been confirmed to work in favor of unproven and arguably risky treatments.
Prescriptions increased 2.5 times in cancer patients
The study analyzed electronic medical records from 68,373,949 patients across 67 health systems in the United States in search of prescribing rates of ivermectin and benzimidazole.
There have been no clinical trials on ivermectin-benzimidazole’s safety and efficacy for treating cancer in people.
Some cell and animal studies show that the drugs can produce anti-cancer activity. But the dose needed to have even a small effect would typically be considered toxic for humans, said Skyler B. Johnson, MD, of the University of Utah Huntsman Cancer Institute. Johnson wasn’t involved in the study but told CIDRAP News that he worries how ivermectin might affect the way the body processes cancer treatments and other medications.
Despite this lack of proof and possible danger, Gibson claimed on Rogan’s podcast in January 2025 that a combination of ivermectin and benzimidazole cured cancer in several of his friends.
The episode was viewed 60 million times within the first month, and prescribing rates of both medications rocketed.
Prescribing doubled among all patients from January 1, 2025, to July 31, 2025, compared with January 1, 2024, to July 31, 2024. For cancer patients, rates were even higher, increasing 2.5 times.
White patients, men, and people living in the South were most likely to have an ivermectin-benzimidazole prescription, according to the study.
The role of celebrity influencers
Even if people are unharmed by taking these medications, needless prescribing creates excess expense and clogs up an already dysfunctional medical system, explained lead author Michelle Rockwell, PhD, RD, a health services researcher at Virginia Tech.
“Clinicians talk about how difficult it is when the patient demands or asks for a medication that they really feel passionately might help,” she said. “And that’s where I think these celebrity influencers really play a big role.”
Frustrations with the healthcare system, pharmaceutical pricing, and insurance barriers create real grievances that make people easier to exploit, explained Matthew Facciani, PhD, a social scientist at the Yale School of Public Health who wasn’t involved in the study.
“We don’t know whether patients were taking ivermectin alongside conventional treatment or in place of it,” said Facciani. “This is a distinction with very different public health implications.”
Ivermectin was also viewed as potential treatment for COVID-19 early in the pandemic, but several clinical trials found it did not lower the risk of severe disease, prevent hospitalization, or speed time to recovery. Misinformation about the drug was linked to a surge in overdose calls to poison control centers in 2021.
Silver linings
The study’s authors acknowledge that they tracked only whether a patient received a prescription and not whether they used the drug. Also, some people might have tried to access these medications without a prescription. For example, agricultural retailers sell formulations of ivermectin for livestock.
And while the prescribing spike occurred after Gibson’s appearance on Rogan, the findings don’t account for whether other factors drove this activity. Still, the timing suggests that the actor’s endorsement had a powerful effect.
If celebrities can convince people to make poor medical decisions, they can potentially do the opposite. Rockwell noted that after Katie Couric had a colonoscopy on TV in 2000, the nationwide rate of colorectal cancer screening increased by 20%.
Also, the demographic patterns revealed in the study “essentially hands public health a map” of where these trusted messengers are most needed, said Facciani.
“The clinical encounter is likely too late and too brief to be the primary intervention point,” said Facciani. “What’s needed instead is more public health presence in digital spaces, meeting people where they already are.”