Fact Check-FDA says male infertility is not a known side-effect of ivermectin

Fixing typos in verdict

A 2011 study out of Nigeria that evaluated 37 subjects is not evidence that ivermectin, an FDA approved drug for treating parasites in animals and humans, is linked to male infertility. According to the U.S. regulator, infertility is not a known side effect of the drug. The drug has been touted on social media as a supposed miracle cure against COVID-19, but the FDA warns against using it for the viral infection.

Claims embracing ivermectin as a COVID-19 treatment often run alongside anti-vaccine narratives ( here , here ). At the time of this article’s publication, ivermectin is not approved to treat or prevent COVID-19 in the United States ( here ), Britain ( here ) or the European Union ( here ).

Separately, there is no widespread evidence that ivermectin is linked to decreased sperm function. The allegation spread on social media following reports that mentioned a 2011 Nigerian study viewable ( here ).

“Ivermectin causes sterilization in 85 percent of men, study finds,” reads one tweet ( here ). Some other examples have been deleted.


The 2011 study ( here ) was authored by four scholars in Nigeria. Titled, “Effects of Ivermectin therapy on the sperm functions of Nigerian onchocerciasis patients,” it evaluated the effect on sperm for 37 patients diagnosed with onchocerciasis, also known as river blindness ( here ), a disease caused by parasitic worms.

The authors evaluated the subjects before and after an 11-month treatment with ivermectin, which is commonly used to treat the disease.

Among their findings, the authors reported to observe a “significant reduction in the sperm counts and sperm motility of the patients tested” and a “significant increase in the number of abnormal sperm cells”. The authors also acknowledge no recording of “any significant change or alteration in the sperm viscosity, sperm volume, and sperm liquefaction time of the patients”.

Reuters contacted Blessing Idonije and Ifeoma Nneka Nweke, two of the authors of the study, and did not receive a response to a request for comment.

Gideon Meyerowitz-Katz, an epidemiologist and researcher at the University of Wollongong in Australia ( here ) took to Twitter to dismiss the claim that this study alone is evidence that ivermectin causes male infertility.

He noted that “It was a small piece of research from nearly a decade ago that excluded 90% of the participants because they had sperm too poor to qualify for inspection. That alone means it's impossible to draw any firm conclusions” ( here ) .

“There's also no control group, so my guess would be that the authors were surveilling a very unwell population who happened to be taking ivermectin. Hard to tell if the medication contributed to that at all,” he added ( here ).

While the Archives of Applied Science Research, the journal that published the study in question, is described as a “peer-reviewed” journal in its website ( here), it does not disclose its peer-review process.

The Archives of Applied Science Research and the Scholars Research Library, the publisher of the journal, did not immediately respond to Reuters request for comment.


A spokesperson from the U.S. Federal Drug Administration told Reuters that infertility is not a known side effect of ivermectin, and it is not currently included as a side effect in its labeling of the drug.

Side-effects listed by the FDA as associated with ivermectin ( here ) include “skin rash, nausea, vomiting, diarrhea, stomach pain, facial or limb swelling, neurologic adverse events (dizziness, seizures, confusion), sudden drop in blood pressure, severe skin rash potentially requiring hospitalization and liver injury (hepatitis)”. More information about this here.

On Sept. 9, the Texas-based KTSM news site issued a correction on their initial story on this study entitled “Ivermectin causes sterilization in 85 percent of men, study finds” ( here ) and said it had been removed from their website ( here ) . “FOR THE RECORD: A national story regarding Ivermectin and a study regarding its effect on men’s reproductive health that KTSM published, has been removed from our website.”.

WFLA, another outlet whose story replicated the KTSM version and was picked up by social media users, also issued a correction and deleted the story here .


No evidence. According to the FDA, infertility is not currently a known side-effect of ivermectin. A Nigerian study from 2011 that concluded ivermectin was related to a decrease in sperm function evaluated only a small sample of 37 patients who had been diagnosed with river blindness.

This article was produced by the Reuters Fact Check team. Read more about our fact-checking work here.