Benzathine benzylpenicillin, also known as benzathine penicillin G, is an antibiotic medication useful for the treatment of a number of bacterial infections. Specifically it is used to treat strep throat, diphtheria, syphilis, and yaws. It is also used to prevent rheumatic fever. It is given by injection into a muscle. It is known as "Peanut Butter Shot" in US military slang due to its appearance.
Side effects include allergic reactions including anaphylaxis, and pain at the site of injection. When used to treat syphilis a reaction known as Jarisch-Herxheimer may occur.
