Whats cyproheptadine hydrochloride?

Antihistamine.: This is an antihistamine used to treat allergic reactions (hay fever). It has other uses also, like treating nightmares related to post traumatic stress disorder, cases of serotonin syndrome, in serotonin producing carcinoid tumor, migraines in children and adolescents, and in the treatment of cyclical vomiting syndrome. It has side effects, like drowsiness, dizziness, and low growth hormone.