Ivermectin, a long-used antiparasitic treatment for both humans and animals, has recently usurped hydroxychloroquine as the “do your own research” internet crowd’s go-to panacea for covid-19. It’s widely discussed in Facebook groups, peddled by shady websites, and even mentioned by Fox News hosts. Swaths of people are now convinced that ivermectin both treats and prevents covid-19. In reality, though the drug has valuable uses, evidence for ivermectin’s potential as an antiviral treatment or preventative is still being gathered and is currently very shaky. Public health experts are now having to warn people away from buying ivermectin meant for animals and using it as an off-label prophylactic, since it can cause dangerous overdoses that land people in the hospital.
So what exactly is ivermectin? And is there really any hope that it may turn out to be a valuable tool against covid-19?
Though ivermectin has gotten a rough reputation lately, often being referred to dismissively as a horse dewormer, that’s really selling it short. For decades, it’s been an invaluable drug for both animals and people, and it’s considered one of the most essential medicines we have by the World Health Organization. The discoverers of its drug class even won the Nobel Prize in 2015. Ivermectin is so treasured not only because it can reliably treat a wide range of parasitic infestations, but because it’s become a cheap generic that can be easily provided to poorer areas of the world. It’s able to be given as a pill, topical gel, or in a liquid bath, as some farmers do with their sheep. Ivermectin has what scientists call a “broad spectrum of activity,” meaning that it can target a lot of different parasites effectively.
Over the years, scientists have wondered whether the drug’s versatility could apply to other types of infection, including those caused by viruses. So it didn’t take long into the covid-19 pandemic before some researchers started looking at ivermectin once again. And sure enough, there was some early research showing that it was very potent at killing the virus in a lab setting—which, of course, is different from being able to help people infected with the germ.
The trouble started when these early results were perceived as concrete proof that ivermectin would be a sure-fire effective treatment for covid-19 by some scientists and many self-proclaimed experts on the pandemic. Even at the time, many researchers cautioned against overhyping these results, since ivermectin isn’t that easily absorbed by the human body. Normally, that’s never been a problem, because it actually doesn’t take a high dose to work when used as an antiparasitic. But translating the dosage used in the lab to kill the coronavirus over to the real world, some scientists have argued, would probably require a much higher dose than could ever be safely used in people. Though safe otherwise, a too-high dose of ivermectin could very well harm people and cause neurological problems, among other things, or interact badly with other drugs.
Still, given the lack of any effective treatments at the time, it was absolutely worth trying ivermectin out. Unfortunately, most studies in the past year that claim to show a benefit from the drug in treating or preventing covid-19 seem to be very low quality, while some have turned out to be based on fraudulent or otherwise suspect data and subsequently withdrawn. And when you look at the largest trials or the overall evidence, you find little to no effect for ivermectin.
Despite these developments, the drug has become wildly popular among certain groups, particularly on social media. These groups, often right-leaning and dismissive of the pandemic otherwise, will argue that the truth about ivermectin has been suppressed and that it’s now kept away from the public at the behest of Big Pharma. These same claims were made about the antimalarial hydroxychloroquine when it was heralded as a potential covid-19 cure. (Hydroxychloroquine was studied in covid-19 patients around the world as a potential therapy, but the results were sadly underwhelming.)
The pharmaceutical industry has serious issues, and it hasn’t shied away from profiteering off the pandemic at times. However, the life-saving drug most widely used during this entire pandemic has been a cheap steroid called dexamethasone. Meanwhile, many of the leading proponents of ivermectin have themselves been accused of profiting off the gullible and desperate by pushing them to buy ivermectin and other supposed preventive treatments via their own businesses. When ivermectin isn’t available through unscrupulous grifters, these online groups will tell people to buy it from animal supply stores and self-administer it. And in Mississippi at least, that bad advice has led to a rash of poison control calls from people who followed it and took the drug.
The Centers for Disease Control and Prevention recently issued a warning to people to not use ivermectin without a prescription, citing two serious cases where people ended up in the hospital with hallucinations and confusion. Last week, the Food and Drug Administration did the same in a memorable tweet reminding us that: “You are not a horse. You are not a cow. Seriously, y’all. Stop it.”
It should be emphasized that these warnings aren’t happening because ivermectin is an unsafe drug when taken as intended. Even in covid-19 clinical trials where people were given a higher dosage than usual under medical supervision, there didn’t seem to have been any major added risk of health problems. But people can overdose on ivermectin and develop symptoms like nausea, vomiting, and diarrhea, while very high doses can cause neurological complications like hallucinations, seizures, and death. There’s also the inconvenience of taking an unneeded drug that has its side effects, as all drugs do. And some ivermectin users may be overconfident and no longer worried about the risk of catching or spreading the coronavirus—a risk that could actually be substantially avoided by getting vaccinated.
It’s not impossible that ivermectin could have a second life as a covid-19 drug, even now. In June, the UK’s Oxford University announced it would add the drug to its ongoing PRINCIPLE trial, advertised as the world’s largest clinical trial of possible covid-19 treatments for people who don’t need hospitalization. The hope is that ivermectin could help prevent people’s early symptoms from getting worse and/or help them clear their infection sooner.
But given the evidence so far, it’s not looking likely that the drug will provide anything more than a modest benefit, if that. Ivermectin is more than a simple animal dewormer, but it’s definitely not a miracle cure for covid-19 or a barrier to getting infected.