What Is Ivermectin? The Anti-Parasitic Drug Investigated As a COVID Treatment

Throughout the COVID pandemic, various treatments have been touted as a weapon against the virus. Hydroxychloroquine was one such medicine, which was controversially pushed by former President Donald Trump and other right-wing figures despite safety concerns and a lack of strong evidence that it actually worked. Ivermectin has also been touted as a COVID treatment, but no studies into its use in this way have yet proven definitive. There have also been cases reported of people being hospitalized after self-medicating with ivermectin, which was initially intended for horses, according to the Food and Drug Administration (FDA).

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What Is Ivermectin?

Ivermectin is an anti-parasitic drug that is approved by the FDA for use in humans to treat certain parasitic worm infections—but not for the treatment of any viral infection such as COVID-19. Examples of parasites and parasitic infections that ivermectin can treat include strongyloides, onchocerciasis, head lice and more. It is also used to treat certain parasitic infections in animals; but this type of ivermectin is not to be used by humans.

Can It Be Harmful?

Ivermectin is approved for human use by the FDA for certain conditions, but it can be harmful in large doses. Dr. Penny Ward, a visiting professor in pharmaceutical medicine at King's College London, told Newsweek ivermectin has been associated with allergic reactions and can also worsen pre-existing liver or kidney disease. Ward also said ivermectin is contraindicated—or not to be used—by pregnant women based on foetal damage observed in animal studies. It is also important to highlight that ivermectin for use in animals is not the same as that used in people, and animal drugs are often highly concentrated for bigger doses. The FDA states such high doses can be "highly toxic" in humans. "Overall, it's a relatively safe medicine at the normal prescribed doses," Dr. David Boulware, professor of medicine and an infectious disease expert at the University of Minnesota medical school, told Newsweek. "But you can also buy veterinary formulations on Amazon, over the counter and stuff like that, which are not normal human doses. They're what you'd give a horse, and you can certainly develop toxicity."

Is It As Controversial As Hydroxychloroquine?

Two experts told Newsweek that this is unlikely. Ward said that at doses being used, ivermectin "is not likely to be as harmful as hydroxychloroquine, which can (and did) cause cardiac problems in recipients." Boulware said that the data with ivermectin "looks much more promising than in hydroxychloroquine," but stopped short of calling for its use as a COVID treatment in the U.S. until more evidence becomes available. Nonetheless, he added that "the same sort of crowd" that latched onto hydroxychloroquine have been supporting ivermectin. In June, Republican Senator Ron Johnson was suspended from YouTube temporarily for sharing a clip in which he touted both hydroxychloroquine and ivermectin as COVID-19 treatments, the Washington Post reported.

Is It Useful for COVID?

Some studies have suggested it might be. The medicine has been reported as having antiviral effects in viral culture studies—that is, in a lab dish. Boulware said: "It presumably is doing something on the human cellular level to block replication of the virus. There's been a little bit of handwaving on what the exact mechanism is." However, the downside is that the amount of drug needed to inhibit the virus in the human body is prohibitively large. According to the U.S. National Institutes of Health (NIH), while ivermectin has been shown to stop the COVID-19 virus from replicating in cell cultures, studies suggest that the dosage necessary to replicate this in humans would need to be 100 times higher than is currently approved for use. Plus, an antiviral effect in a petri dish does not necessarily mean the drug will work so well in the real world, according to Dr. Peter English, a recently retired consultant in communicable disease control at Public Health England. English told Newsweek: "Despite widespread endorsement by [the] optimistic, the research so far has not convincingly shown that ivermectin is usefully effective in preventing or treating COVID-19, and it is very unlikely that the benefits of using it would outweigh the risks." Ongoing studies into the effectiveness of ivermectin include the U.K.'s PRINCIPLE trial, which is searching for COVID-19 treatments. One major study which suggested ivermectin was effective against COVID, led by Dr. Ahmed Elgazzar from Benha University in Egypt, was recently withdrawn from the Research Square pre-print website due to "ethical concerns," reported The Guardian newspaper earlier in July. Research Square did not outline its ethical concerns but Nick Brown, a data analyst affiliated with Linnaeus University in Sweden who reviews scientific papers for errors, told The Guardian that at least 79 of the patient records in the study were "obvious clones of other records." "It's certainly the hardest to explain away as innocent error, especially since the clones aren't even pure copies. There are signs that they have tried to change one or two fields to make them look more natural," added Brown. The study's removal is thought to be significant because it was often cited.