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Home » Horse dewormer ivermectin still doesn’t work for COVID

Horse dewormer ivermectin still doesn’t work for COVID

Last updated on July 17th, 2023 at 12:50 pm

There has been a lot of scientific evidence that the horse dewormer ivermectin does nothing for COVID-19, but people keep trying to make it appear that it works. But now we have another large study that shows that ivermectin still doesn’t do anything for COVID-19. If you just happen to have a parasitic infection along with COVID-19, then it will help — with the parasitic infection.

Well, let’s look at this new study, just to place the final nail in the coffin for using ivermectin to treat COVID-19. Who am I kidding? Vaccine deniers will never give up pushing this useless treatment over vaccines.

Humans, stay away from our dewormer. Photo by Raphael Wicker on Unsplash

What is ivermectin?

Let me start with ivermectin itself. It is an antiparasitic drug. It was discovered in 1975, and its first uses were in veterinary medicine to prevent and treat heartworm and acariasis. It was approved for human use in 1987 — it is used to treat infestations including head lice, scabies, river blindness, strongyloidiasis, trichuriasis, ascariasis, and lymphatic filariasis, all parasitic infections.

William Campbell and Satoshi Ōmura won the 2015 Nobel Prize in Physiology or Medicine for its discovery and applications. The Nobel Prize was for the two scientists who developed such an important medicine — it was not given for the drug itself, despite wild claims on the internet.

As you will notice, there are no claims made by the researchers or other scientists that ivermectin affects viruses, including SARS-CoV-2 which causes COVID-19. The myth that ivermectin had some effect on SARS-CoV-2 was the result of an in vitro study, which is essentially a study in a test tube, not a real living human being. Furthermore, less than 1% of drugs that work in vitro ever end up with any clinical usefulness.

Then a series of very badly designed trials, with serious methodological issues, tried to show that ivermectin worked to treat COVID-19, but most scientists rejected those claims for bad study design, bad statistical analysis, and bad conclusions. However, anti-vaxxers being their usual anti-science selves, decided that ivermectin was all that was needed, not vaccines.

So, you’re wondering why we call it a “horse dewormer.” It’s because delusional people who thought it treated COVID-19 bought up the horse version of ivermectin because they would need to see an actual doctor for a prescription for the human version, and they knew 99.9% of physicians would have laughed at them.

Really humans, stay away from my meds. Photo by Aurélien Faux on Unsplash

The new ivermectin and COVID-19 paper

In a paper published on 5 May 2022 in the New England Journal of Medicine, by Edward Mills, a professor of health sciences at McMaster University in Hamilton, Ontario, Canada, and colleagues, the horse dewormer ivermectin was no better than a placebo at preventing hospitalizations in COVID-19 patients. This clinical trial, which included nearly 1,400 Covid-19 patients at risk of severe disease, is the largest to show that those who received ivermectin as a treatment for COVID-19 didn’t fare better than those who received a placebo.

Dr. Mills and colleagues examined 1,358 adults who visited one of 12 clinics in the Minas Gerais region of Brazil with COVID-19-19 symptoms. The patients all had a positive rapid test for SARS-CoV-2 and were at high risk of having a severe case for reasons including a history of diabetes, hypertension, cardiovascular disease, or lung disease.

In the randomized, double-blind clinical trial, the researchers gave half of the patients a course of ivermectin pills for three days while the other half received a placebo. They tracked whether the patients were hospitalized within 28 days of receiving ivermectin or the placebo. The clinical endpoints of the study were whether patients on ivermectin cleared the virus from their bodies faster than those who received a placebo, whether their symptoms resolved sooner, whether they were in the hospital or on ventilators for less time, and whether there was any difference in the death rates for the two groups.

Mills and colleagues analyzed the data in three different ways to make certain that they were thorough. They looked at data from all patients; then analyzed data from patients who received ivermectin or a placebo 24 hours before they were hospitalized; and in a third review, looked at data from patients who said they had adhered strictly to their dosing schedule. In each scenario, they found ivermectin did not reduce the risk of hospitalization.

Dr. Mills presented the results of the peer-reviewed study at a forum sponsored by the National Institutes of Health. He told The Wall Street Journal that:

There was no indication that ivermectin is clinically useful.

Dr. Peter Hotez, dean of the National School of Tropical Medicine at Baylor College of Medicine, reviewed the findings and told The Wall Street Journal:

This is the first large, prospective study that should really help put to rest ivermectin and not give any credibility to the use of it for Covid-19.

I hope so, but we all know better.

So, we have more data added to a fairly large body of evidence that ivermectin is ineffective in treating COVID-19. And we also know that taking large doses of the drug is dangerous, according to the FDA. 

There are actual FDA-approved drugs that can treat COVID-19 successfully — Merck’s molnupiravir and Pfizer’s Paxlovid. And researchers, including Dr. Mills, are studying other drugs with an anti-viral activity that might be useful in treating COVID-19. Still, those will only be available once we know that they actually work in large clinical trials.


This is simple — ivermectin is useless in treating, preventing, or reducing symptoms of COVID-19. Let the horses have their dewormer, there are other drugs that are actually effective against COVID-19.


  • Reis G, Silva EASM, Silva DCM, Thabane L, Milagres AC, Ferreira TS, Dos Santos CVQ, Campos VHS, Nogueira AMR, de Almeida APFG, Callegari ED, Neto ADF, Savassi LCM, Simplicio MIC, Ribeiro LB, Oliveira R, Harari O, Forrest JI, Ruton H, Sprague S, McKay P, Guo CM, Rowland-Yeo K, Guyatt GH, Boulware DR, Rayner CR, Mills EJ; TOGETHER Investigators. Effect of Early Treatment with Ivermectin among Patients with Covid-19. N Engl J Med. 2022 May 5;386(18):1721-1731. doi: 10.1056/NEJMoa2115869. Epub 2022 Mar 30. PMID: 35353979; PMCID: PMC9006771.
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