Joe Rogan, the host of Spotify’s most popular podcast, has contracted Covid, he announced on Wednesday. He says he is feeling better – but his health update undoubtedly made health experts instantly sick. On Instagram, the podcaster, who professes not to be “an authority on health” but has discouraged young people from getting the coronavirus vaccine, said that he had “immediately thrown the kitchen sink” at his infection. Among the many medications he used, he said, was ivermectin, a drug mainly used to deworm horses. Rogan, described by the New York Times as “one of the most consumed media products on the planet”, has legions of devoted followers. Some episodes of The Joe Rogan Experience have boasted tens of millions of downloads, and his recommendations for everything from supplements to shaving supplies can be a godsend for companies. That’s why his apparent endorsement of a horse medicine totally unproven as an effective treatment for Covid-19 is concerning. Though ivermectin can be prescribed to target parasitic infections in humans, the US Food and Drug Administration has not approved the drug for use against the coronavirus. In large doses, the FDA warns, it can be dangerous, with side effects including “nausea, vomiting, diarrhea, hypotension (low blood pressure), allergic reactions (itching and hives), dizziness, ataxia (problems with balance), seizures, coma and even death”. But after an Australian study last year that found ivermectin could kill Covid in a lab, chatter about the drug has exploded online. Politicians and rightwing talkshow hosts have promoted it – even as the very researchers behind the study warn against it. In the US, prescriptions for the drug have soared from 3,600 weekly before the pandemic to more than 88,000 in a week last month, per CDC data. At the same time, poison control centers have seen calls related to ivermectin explode, reaching five times their usual rate in July, the Washington Post reported. Rogan’s announcement is not his first widely criticized tango with ivermectin. The 22 June episode of his podcast features an interview with Dr Pierre Kory, who testified to US senators in December about ivermectin and called it a “miracle drug”. But experts strongly disagree, and forcefully warn against self-treating with the medication. “I plead with people to stop using ivermectin and get the vaccine because it’s the best protection we have at this point,” the toxicologist Shawn Varney told the New York Times. “Everything else is risk after risk.” A study touting the drug was withdrawn due to ethical concerns, with authors apparently having simply used a thesaurus to alter paragraphs from press releases about the drug.