Ivermectin

Ivermectin is an antiparasitic medication derived from avermectin, a compound discovered in soil bacteria by Satoshi Ōmura and developed into a human/veterinary medicine by William Campbell -- work that won the 2015 Nobel Prize in Physiology or Medicine. It works by binding glutamate-gated chloride channels found in the nerve and muscle cells of parasites (channels human cells don't share at these sites), causing paralysis and death of the organism. Its FDA-approved oral form treats intestinal strongyloidiasis and onchocerciasis (river blindness); a topical cream treats the inflammatory lesions of rosacea (the FDA label notes the exact mechanism for rosacea is unknown, though anti-inflammatory and anti-Demodex-mite activity are believed to contribute); and a topical lotion treats head lice. It's also widely used off-label for scabies per CDC treatment guidance, though it isn't FDA-approved specifically for that use. Ivermectin has also drawn anecdotal and community interest well beyond these approved uses -- including claims around antiviral, anti-inflammatory, anti-cancer, and longevity/anti-aging effects, some of it based on laboratory (preclinical) research into these mechanisms. That interest hasn't been backed by human clinical trials for any of these uses, so none of it is an established or evidence-based benefit. The one repurposed use that HAS actually been tested in large human trials is COVID-19: ivermectin drew major public attention during the pandemic as a proposed treatment, but the NIH-funded ACTIV-6 trial and the Brazilian TOGETHER trial specifically tested it and found no meaningful benefit for treating or preventing COVID-19, which is why the FDA, CDC, and NIH do not recommend it for that purpose.