Used primarily as an anthelmintic in veterinary medicine to treat parasitic worm infections in livestock and companion animals. It works by paralyzing nematodes through inhibition of acetylcholinesterase, leading to expulsion of the parasites from the host. Also investigated for immunomodulatory effects in certain autoimmune conditions and as an additive in research settings to study immune responses. Has been used historically in some human medications, though largely replaced by safer derivatives.