Ivermectin, an anti-parasitic drug often used to deworm horses and cattle, does not reduce the risk of being hospitalized with COVID-19 despite its questionable rise as an alternative treatment for the disease, according to a large new study published in the New England Journal of Medicine.
The clinical trial, which began in 2020, analyzed more than 1,300 patients in Brazil who were infected with the coronavirus. Half were given ivermectin and half a placebo in the randomized, double-blind study, meaning neither doctors nor trial participants knew what a patient received.
The results confirmed what U.S. health officials have long stressed: Ivermectin did nothing to aid those sickened with the virus or reduce the risk of ending up in the hospital.
“Treatment with ivermectin did not result in a lower incidence of medical admission to a hospital due to progression of COVID-19 or of prolonged emergency department observation among outpatients with an early diagnosis of COVID-19,” researchers wrote Wednesday.
The data had been shared at a presentation to the National Institutes of Health last August, but the publication Wednesday was the first time results were shared in full.
Researchers in the trial initially gave patients a one-day dose of ivermectin, which is commonly used to treat parasitic diseases, but they also adapted the trial to give some patients the drug in the first three days after a positive COVID-19 test. That group, they found, actually had worse outcomes than those who took a placebo.
Clinical trials had already shown that ivermectin was not effective against COVID-19, and both the Food and Drug Administration and the Centers for Disease Control and Prevention issued repeated warnings to Americans not to self-medicate. But it is still pushed as an alternative treatment, including being touted by Spotify podcaster Joe Rogan and given to inmates in Arkansas.
The drug was among thousands that were initially looked at in the early days of the pandemic, The New York Times noted, when researchers were scrambling to see if treatments for other ailments could potentially be used to combat COVID-19. Preliminary experiments suggested at the time that ivermectin might block the coronavirus, and some doctors began prescribing it despite FDA warnings. Some people began turning to farm supply stores to buy dosages of the drug used for livestock, overdosing on medication meant for much larger creatures. It also created a shortage of the drug.
Research into the possible usefulness of older drugs waned as safe, effective vaccines became widely available in the U.S. and new anti-viral treatments came onto the scene.
Dr. Lindsey Baden, the deputy editor of the New England Journal of Medicine, said in a podcast Wednesday that the spread of misinformation about ivermectin muddled the public’s reaction to treatments that were proved to actively prevent or treat COVID-19.
“If there are active treatments, it is better to use those agents than agents that we wish worked but have no evidence that they work,” Baden said. “So I see the real danger in repurposed drugs that don’t work is that they confuse the early clinical treatment of our patients.”