Largest Study of Ivermectin Shows No Protection Against COVID-19 Hospitalizations

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Lara Antal / Verywell

Key Takeaways

  • A large, randomized study of COVID-19 patients in Brazil shows that being treated with ivermectin has little or no benefit.
  • The study found that there was no difference in hospitalization rates between patients who received placebo and those who received ivermectin.
  • Ivermectin has been touted as a treatment or prevention method for COVID-19 since early in the pandemic, but clinical trials have never backed this claim.

A new study published in the New England Journal of Medicine shows that treating COVID-19 patients with ivermectin early in the course of their infection does not reduce their risk of hospitalization. This is the largest study yet to show there is no benefit to using the drug, which is normally used to treat parasitic infections in humans and animals, as a COVID-19 treatment.

The researchers behind the study hope the findings will put an end to the notion that ivermectin could ever be an effective COVID-19 treatment, encouraging people to turn to prevention and treatment methods that are safe, proven, and authorized instead. But they know they can't change everyone's minds.

"Our clinical trial is the largest one yet of ivermectin for the early treatment of COVID. It did not show a statistically significant benefit," Edward Mills, PhD, study author and a professor at McMaster University in Hamilton, Ontario, told Verywell. "I think it will influence those who were uncertain about whether or not further research might provide more precise answers. I do not think it will influence people whose minds have already been made up about whether or not it works."

What Is Ivermectin?

Ivermectin is FDA-approved to treat different diseases caused by parasitic worms, such as intestinal strongyloidiasis and onchocerciasis. It's typically offered as a tablet, though topical formulations are available to treat lice and rosacea. Ivermectin is extremely dangerous in high dosages. People taking the drug must follow their prescriptions carefully.

The type and dosage of ivermectin used as a dewormer in animals is different from the ivermectin used in humans.

No Proof of Reducing COVID-19 Hospitalization

The ivermectin study, which was part of a larger clinical trial known as TOGETHER, enrolled 1,358 adult patients in Brazil with COVID-19 who were within seven days of symptom onset. These patients also had at least one factor that increased their risk of progressing to more severe illness or hospitalization, such as an underlying chronic illness like diabetes or heart disease.

Half the patients received ivermectin for three days (400 micrograms per kilogram of body weight) and half received a placebo, but neither the patients nor the healthcare professionals administering the treatments knew who got which. Researchers tracked the patients to see how many needed hospitalization due to worsened COVID-19 symptoms within 28 days of the study.

Ultimately, 211 patients were admitted to the hospital or went to an emergency room. One hundred (14.7%) were in the ivermectin group and 111 (16.3%) in the placebo group—a statistically insignificant difference.

Researchers also evaluated whether the patients on ivermectin cleared the virus from their bodies faster than those who took the placebo, or if they stopped experiencing symptoms sooner. They did not.

This study did not completely rule out a potential for a small benefit from treatment with ivermectin, Mills said.

"But given that there are other interventions out there that have some statistical significance, then a topic like ivermectin, where the finding is still uncertain after many, many trials, leads one to believe that it's just not a drug worth pursuing any further,” he said.

There are several other large, randomized trials of ivermectin for COVID-19 that are still underway. A division of the National Institutes of Health, the Center for Advancing Translational Sciences, has been running a large study for more than a year.

The Ivermectin Controversy

Ivermectin has been touted by some as a miracle drug since June 2020, when a study showed it was capable of reducing COVID-19 viral load in a lab setting, but not actually in a living organism. The dosage necessary to achieve an effect would not be safe for humans to take.

Several subsequent studies of ivermectin use for COVID-19 in humans have been retracted. Last year, a Cochrane Review of randomized, controlled clinical trials concluded that “based on the current very low- to low-certainty evidence, we are uncertain about the efficacy and safety of ivermectin used to treat or prevent COVID-19. The completed studies are small, and few are considered high quality.”

Despite messaging from the Food and Drug Administration (FDA) not to do so, some physicians started to prescribe ivermectin for COVID-19. Many people obtained it on their own at farm supply stores, where versions used for livestock are available without a prescription.

"For most people that that take care of COVID-19 patients—infectious disease physicians like myself—there's never really been any debate over ivermectin,” Amesh A. Adalja, MD, a senior scholar at the Johns Hopkins Center for Health Security, told Verywell. "Any time there's been a rigorous study with ivermectin, there is no benefit shown."

Adalja explains that this latest study is probably not enough to put an end to conspiracy theories that fuel ivermectin use—like that the pharmaceutical industry is suppressing the drug because it's cheap.

"What keeps the interest in ivermectin as a COVID treatment going is not science,” Adalja said. “This is another study that really should put the whole ivermectin issue to rest. But unfortunately, it probably won't, because the people who advocate for ivermectin always have some objection, or because they're not able to be rationally engaged with on this.”

A real risk of the focus on ivermectin use for COVID is that it diverts attention from more effective treatments.

"There are good antivirals out there like Paxlovid and molnupiravir, and even fluvoxamine," Adalja said. "However, they get much less attention than ivermectin."

What This Means For You

You should not take ivermectin to treat COVID-19. There is no evidence it will make your infection any less severe.

The information in this article is current as of the date listed, which means newer information may be available when you read this. For the most recent updates on COVID-19, visit our coronavirus news page.

6 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Reis G, Silva EASM, Silva DCM, et al. Effect of early treatment with ivermectin among patients with COVID-19N Engl J Med. Published online March 30, 2022. doi:10.1056/NEJMoa2115869

  2. U.S. Food & Drug Administration. Stromectol.

  3. U.S. Food & Drug Administration. Why you should not use ivermectin to treat or prevent COVID-19.

  4. National Center for Advancing Translational Sciences.  Large clinical trial to study repurposed drugs to treat COVID-19 symptoms.

  5. Caly L, Druce JD, Catton MG, et al. The FDA-approved drug ivermectin inhibits the replication of SARS-CoV-2 in vitroAntiviral Res. 2020;178. doi:10.1016/j.antiviral.2020.104787

  6. Popp M, Stegemann M, Metzendorf M-I, et al. Ivermectin for preventing and treating COVID-19Cochrane Database Syst Rev. 2021;7(7). doi:10.1002/14651858.CD015017.pub2

By Valerie DeBenedette
Valerie DeBenedette has over 30 years' experience writing about health and medicine. She is the former managing editor of Drug Topics magazine.