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Male sterility not a known side effect of ivermectin

September 10, 2021 GMT

CLAIM: Ivermectin causes reduced sperm count or sterility in men.

AP’S ASSESSMENT: False. The U.S. Food and Drug Administration says claims that the parasite drug ivermectin can cause infertility in men are unproven. The study used to support the claims was based on about three dozen men in Nigeria a decade ago, and has been called into question for flaws in its research methods as well as problems with the journal’s peer review process.

THE FACTS: As coronavirus cases climb during a fourth wave of the pandemic, social media posts have reemerged erroneously touting ivermectin, a cheap drug used to kill worms and other parasites in humans and animals, as a proven treatment for COVID-19.

Health officials and experts have called for people to stop using the unproven treatment — especially the versions meant for animals — warning that incorrect doses could cause harmful side effects such as nausea, vomiting, diarrhea, seizures, delirium and even death. “Currently available data do not show ivermectin is effective against COVID-19,” reads an FDA statement discouraging its use for that purpose.

Amid the warnings surrounding ivermectin, posts and news articles surfaced claiming that another known side effect of the drug was reduced sperm count, or even male sterility.

But the FDA said in an emailed statement to the AP that infertility in men is not a known side effect of ivermectin and is not included as a side effect on labels. The agency said trials of the drug on rats found it had no adverse effects on fertility after the rats were given repeated doses of up to three times the maximum recommended human dose.

Claims that the drug can have an adverse effect on male sperm counts are largely linked to a single 2011 study conducted in Nigeria. The study is hosted online by the Scholars Research Library under a journal called the Archives of Applied Science Research, which states that it is a peer reviewed, open access online publication.

However, the host site has been listed on multiple databases tracking suspicious or potentially predatory publishers that may print research papers without proper peer review processes or may accept payment in exchange for the publishing of studies that may not otherwise meet academic standards.

The journal does not include a section defining how it verifies or reviews its studies and the Twitter account linked to the journal has been suspended due to violating the platform’s policies.

The study focused on male patients diagnosed with river blindness, a parasitic tropical disease. Initially, 385 men were screened for participation in the study, but just 37 of those — less than 10% — were found to have normal sperm counts before the study began. The other patients’ counts were already too low or they were deemed too sick to be eligible.

The sperm counts of those 37 patients were then analyzed before and after being treated with ivermectin for 11 months. The study concluded that following this period, there was a “significant reduction in the sperm counts and sperm motility of the patients tested.”

However, the study did not include key elements often needed in credible scientific research, including the use of a control group to compare whether ivermectin caused the issues, or whether other problems were to blame, including pre-existing health conditions or the severity of their river blindness infection. It also did not include a section outlining limitations that could have impacted the interpretation of the findings. Furthermore, researchers did not say whether the alleged sperm reduction was temporary or permanent.

The study was cited in a Sept. 8 article by a Texas news station which reiterated some of the findings and used the headline: “Ivermectin causes sterilization in 85 percent of men, study finds.”

The station has since removed the article, citing in an editor’s note that it pulled the story following “concerns over the scientific research methods, the veracity of the original, peer-reviewed report and public statements by the Food and Drug Administration (FDA) saying that infertility is not a known side effect of ivermectin.”

Multiple attempts by the AP to reach the host site, the journal and the authors of the study were not answered.


This is part of AP’s effort to address widely shared misinformation, including work with outside companies and organizations to add factual context to misleading content that is circulating online. Learn more about fact-checking at AP.