About Cyproheptadine Piperidine (nonselective) First Generation H1 Antagonist ,anticholinergic and antiserotonergic(5-HT2 receptor antagonist), antihistaminic,appetite stimulant. Mechanism of Action of Cyproheptadine Cyproheptadine is a sedative antihistamine with serotonin antagonist, and calcium-channel blocking actions. It competes with Histamine for H1 receptors present in the smooth muscle of gastrointestinal tract, bronchi, large blood vessels and uterus. Histamine cannot bind with H1 receptors and cannot produce histamine induced allergic symptoms. Cyproheptadine blocks serotonin receptors preferentially block 5HT2A receptor and are useful in migraine prophylaxis. It has weak anticholinergic activity and possesses mild CNS depressant properties. It also blocks voltage sensitive calcium channel in islet of pancreas and smooth muscle. Cyproheptadine increases appetite and cause weight gain.