What is Sumatriptan? Sumatriptan is a prescription medication that falls under the class of drugs known as triptans. It is specifically designed to treat migraines and cluster headaches. Mechanism of Action: Sumatriptan works by stimulating serotonin (a neurotransmitter) receptors in the brain, which causes the blood vessels in the brain to constrict. This alleviates the headache and other sympt..