Papaverine (Latin papaver, “poppy”) is an opium alkaloid antispasmodic drug, used primarily in the treatment of visceral spasm and vasospasm (especially those involving the intestines, heart, or brain), and occasionally in the treatment of erectile dysfunction. It is used in the treatment of acute mesenteric ischemia. While it is found in the opium poppy, papaverine differs in both structure and pharmacological action from the analgesic (morphine-related) opium alkaloids (opiates).