A 2011 study into Ivermectin's affects on the sperm counts of men suffering from river blindness [PDF] found that 85% of them experienced sperm dysfunction of some kind. But as fact-checkers point out, the study hasn't been reproduced and sensational coverage often skips over the fact the research wasn't published in a journal. (Update: On Thurdsay the FDA rejected the study outright)
The study in question was not published in a credible journal, nor was it hosted by an accredited, reputable institution. In the decade since the study's supposed 2011 publication, there has been little — if any — related research to confirm its findings. Furthermore, a spokesperson for the U.S. Food and Drug Administration told Snopes that infertility in men is not a known side effect of ivermectin and, as such, is not included in U.S. labeling requirements.
Nonetheless, Ivermectin is not authorized or approved for treating or preventing COVID-19 in humans or animals, there is little chance of evidence emerging otherwise, and the "horse paste" form for treating animal parasites—which may be bought without a prescription—is dangerous to humans.
