MaryJo Perry raises animals on her property outside of Jackson, Miss., and uses ivermectin to treat her cattle. To her, the drug is as familiar, safe, cheap and effective as vitamins: "We've been using it on the farm for 40 years."
Perry, who studied animal science and at one time wanted to be a vet, also uses it to treat mange in stray dogs she rescues near her home. It works without side effects, she says: "I've never seen issues with it."
In humans, ivermectin fights parasitic infections from roundworm, lice and scabies; it's effective against certain tropical diseases, and may have benefits in fighting malaria.
Its reputation as a miracle drug for animal and human disease began with its discovery in the 1970s. It has driven down cases of river blindness around the world. And scientists initially hoped it might treat COVID-19, too, prompting many people to embrace it, though dozens of studies later confirmed the drug is not an effective treatment.
Despite the disappointing research results, ivermectin took off during the pandemic, fueled by misinformation. Perry, speaking at a political event on medical freedom she organized in September, says she doesn't believe the research finding it ineffective. "I believe that it prevents COVID; I know that firsthand," she claims. "I've taken care of my family with it. Since I started taking it, I've not gotten it again."
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.
Ivermectin prescribing rebounds
During the early years of the pandemic, prescriptions for ivermectin surged to 10 times pre-pandemic levels — as doctors prescribed it off-label. Prescriptions were especially high across the South and among older patients more vulnerable to COVID, says Dr. John Mafi at University of California, Los Angeles, who specializes in geriatrics and tracked ivermectin prescriptions.
Mafi says those numbers, which were waning when he concluded his initial study in 2023, began picking back up in 2024 and increasing in 2025. They were driven, he says, by fresh rounds of disinformation and intensifying mistrust of traditional health information from the government and pharmaceutical companies.
"It became really a symbol of this sort of alternative right-wing movement to defy what the government institutions are telling you and to trust your own intuition," he says. Mafi says policy changes to make ivermectin more available is driven by politics, not medical evidence for the drug's healing power.
In fact, he says the drug — which works by attacking a parasite's nervous system — can have side effects in humans like dizziness, nausea and itchy skin. Excessive doses can even lead to coma or death, the Food and Drug Administration warns.
A dangerous substitute for proven treatments
Last month, Trump's appointed head of the National Cancer Institute, Anthony Letai, said the agency was conducting preclinical studies on ivermectin's ability to kill cancer cells — though doctors say it holds little promise. And Florida's First Lady Casey DeSantis, a breast cancer survivor, touted it in announcing $60 million in cancer research funding, including use of ivermectin.
There's currently no good evidence that ivermectin is an effective cancer treatment in humans.
"Most promising drugs in test tubes and mice don't pan out in humans," Mafi says. "That's just a statistical reality."
And there is already a lot of other cancer research and treatments in the form of targeted immunotherapies that are far more advanced and promising than ivermectin, he says.
Yet that hasn't stopped it from taking off among patients influenced by disinformation.
New Orleans oncologist Jonathan Mizrahi started seeing interest in ivermectin for cancer about a year ago, when he noticed nearly half of his new patients came in asking about it. He was confused. "I was like, 'Ivermectin? I haven't heard about that since medical school.'" Mizrahi knew that studies had debunked its effectiveness in treating COVID.
In fact, when he looked online, Mizrahi found those myths still reverberating in the social media chatosphere. Those then exploded in popularity after actor Mel Gibson suggested on Joe Rogan's podcast last January that ivermectin cured three friends of advanced cancer.
Mizrahi says that appearance, combined with growing public mistrust in government and medicine, convinced some patients to spurn his advice and forgo traditional cancer treatment, putting their faith instead in ivermectin.
"Those are the most heartbreaking because those are patients that we really have stuff that can help, that's tried and true, and they're kind of putting all their eggs in a basket that I don't think is going to be helpful for them," Mizrahi says.
One of his young male patients recently refused chemotherapy in favor of ivermectin and another antiparasitic drug, fenbendazole, to treat his Stage 4 cancer. Mizrahi saw him again months later, by which time a CAT scan showed the cancer had spread.
"It's the rare case where I can actually do almost like a study of one patient and say, 'Hey, look, it didn't work,'" then persuading the patient to resume recommended treatment, he says.
Now, more than ever, Mizrahi says it's critical for doctors like him to spend time getting to know patients to better understand their fears, their sources of information and how politics shape their views on health. "The nature of politics today — where it really does permeate so many dimensions of people's lives — makes its way into the exam room," he says.
Ivermectin's rise to prominence
But how and why has ivermectin become a kind of medical litmus test of political belief?
The answer lies in a bizarre saga that began early in the pandemic, says Spanish researcher Carlos Chaccour at the University of Navarra. "Sadly, I was at the forefront when it all started," says Chaccour, who at the time was among a handful of scientists testing ivermectin's potential use in treating disease — in his case, malaria.
When COVID-19 first began to spread, Chaccour says it made sense to test existing medicines like ivermectin for their effectiveness against the novel virus.
"It's been a wonder drug, and that's why it got the Nobel Prize — because it saved the sight, the limbs and the lives of probably hundreds of millions of people," he says. It was cheap and readily available in agricultural and rural areas around the world, and widely known as a safe, easy-to-take remedy.
Early in 2020, Chaccour says a small company called Surgisphere claimed to have data from Australian patients showing ivermectin effectively fought the new COVID virus. It was slated to publish that research in the prestigious medical journal, The Lancet. "Well, it turned out it was fake — it was completely fake," Chaccour says of the company's research.
Chaccour, who'd never heard of the firm, began investigating, uncovering suspicious details about Surgisphere's data and its executives, who claimed to have the endorsement of a Harvard expert. He discovered its chief promoter, for example, also worked as a Las Vegas event organizer, he says. Its affiliation with Harvard also turned out to be bogus.
At the same time, in the summer of 2020 — based largely on hopes pinned on Surgisphere's preprinted research and fueled by the world's desperate search for a cure — governments of Peru, Bolivia, Venezuela, Brazil, Honduras and other Latin American countries began approving and even distributing ivermectin as a treatment for COVID, even before randomized trials were conducted.
This alarmed Chaccour.
"We actually contacted Surgisphere and said, 'Hey, there's countries issuing national guidelines, partly based on your preprint: Are you sure about this,'" Chaccour says. He asked to see their data, but the company evaded his questions.
Chaccour says he understands why so many people were willing to believe the preliminary reports. "The drug is known; it's affordable," Chaccour says. "People give it to animals…There's a preprint with a Harvard stamp on it, saying it prevents COVID. Governments make it national policy. People start taking it — of course people start taking it."
Polarization deepens
Then, in early 2021, conservative media personalities like Laura Ingraham and Joe Rogan began promoting ivermectin, and the furor reached US shores.
Eventually, Surgisphere's fake preprinted research on ivermectin, as well as its research on another antiparasitic drug hydroxychloroquine was retracted, and the company was discredited, causing scandal in the scientific community. But by then, damage had already been done. And that, Chaccour says, set the stage for ivermectin to take center stage as a symbol of politicized medicine.
The Biden administration's response did not help, either, he says. In 2021, amid a rise in ivermectin poisonings in the US, the FDA tweeted a snarky warning to ivermectin users: "You are not a horse. You are not a cow. Seriously, y'all. Stop it." (That post was later removed following a lawsuit brought by three Texas doctors arguing the FDA overstepped its authority in issuing medical guidance.)
The tone of the FDA's message, Chaccour says, carried with it a contemptuous and toxic undertone, which only helped to escalate the political tensions around ivermectin that continue to this day.
Going forward, Chaccour says he hopes people see that both sides actually share an interest in promoting health — and that that understanding will help depoliticize the drug he's worked with for decades. "It remains a global health miracle today, and it's threatened by this misuse."
NPR's Katia Riddle contributed to this report.
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