In an earlier version of this story, David Boulware incorrectly cited an amount and concentration of animal ivermectin available online and calculated that it would be 100 times the normal human dosage, leading to toxicity. Ivermectin, at the amounts and concentration typically available online, would be more than seven times the normal dosage for an adult human, which could still lead to toxicity. This story has been corrected.
The idyllic photo of a chestnut horse appeared on the U.S. Food and Drug Administration’s Instagram feed in August, along with a blunt caption: “You are not a horse. Stop it with the #Ivermectin. It’s not authorized for treating #COVID.”
The post was one of several stark warnings issued about ivermectin — an anti-parasitic medication being promoted by prominent conservative media figures and politicians, as well as some physicians, as an effective treatment for covid-19, despite the lack of scientific evidence showing there are benefits of taking the drug for that purpose.