Ivermectin is an antiparasitic medication. 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, it is used to treat infestations including head lice, scabies, river blindness (onchocerciasis), strongyloidiasis, trichuriasis, ascariasis and lymphatic filariasis. It interferes with the nerves and muscles of parasites, leading to paralysis. It can be taken by mouth, or applied to the skin for external infestations. It belongs to the avermectin family of medications.