Basically any severe allergic reaction is a histamine response, AFAIK (IANAD). Bee stings, rotten fish, nut allergies, etc. Additionally, there are a large numb

Basically any severe allergic reaction is a histamine response, AFAIK (IANAD). Bee stings, rotten fish, nut allergies, etc. Additionally, there are a large number of ailments that trick the body into attacking itself, like some forms of arthritis, and of course AIDS.