Ivermectin is an antiparasitic drug. After its discovery in 1975, its first uses were in veterinary medicine to prevent and treat heartworm and acariasis. Approved for human use in 1987, today it is used to treat infestations including head lice, scabies, river blindness (onchocerciasis), strongyloidiasis, trichuriasis, ascariasis and lymphatic filariasis. It works through many mechanisms to kill the targeted parasites, and can be taken by mouth, or applied to the skin for external infestations. It belongs to the avermectin family of medications.

William Campbell and Satoshi Ōmura won the 2015 Nobel Prize in Physiology or Medicine for its discovery and applications. It is on the World Health Organization's List of Essential Medicines, and is approved by the US Food and Drug Administration as an antiparasitic agent. In 2020, it was the 423rd most commonly prescribed medication in the United States, with more than 100,000 prescriptions. It is available as a generic medicine.

During the COVID-19 pandemic, misinformation has been widely spread claiming that ivermectin is beneficial for treating and preventing COVID-19. Such claims are not backed by credible scientific evidence. Multiple major health organizations, including the US Food and Drug Administration, the US Centers for Disease Control and Prevention, the European Medicines Agency, and the World Health Organization have stated that ivermectin is not authorized or approved to treat COVID-19.