Sumatriptan is used to treat acute migraine headaches in adults. It is not used to prevent migraine headaches and is not used for cluster headaches. Sumatriptan works in the brain to relieve the pain from migraine headaches. It belongs to the group of medicines called triptans. Many people find that their headaches go away completely after they take sumatriptan. Other people find that their headaches are much less painful, and that they are able to go back to their normal activities even though their headaches are not completely gone. Sumatriptan often relieves other symptoms that occur together with a migraine headache, such as nausea, vomiting, sensitivity to light, and sensitivity to sound. Sumatriptan is not an ordinary pain reliever. It will not relieve pain other than from migraine headaches. This medicine is usually used for people whose headaches are not relieved by acetaminophen, aspirin, or other pain relievers. Sumatriptan has caused serious side effects in some people, especially people who have heart or blood vessel disease. Be sure that you discuss with your doctor the risks of using this medicine as well as the benefits that it can have.