Sumatriptan is a medication primarily used for the acute treatment of migraine headaches in adults, with or without aura. It works by narrowing blood vessels in the brain and blocking pain signals. It is not a preventative medicine and should not be used to treat other types of headaches, such as cluster or basilar migraines. 

Key Information

• Usage: Take a tablet as soon as migraine symptoms start. It is not for prevention and generally starts working within 30 to 60 minutes.

• Dosage: The usual adult dose is 25 mg, 50 mg, or 100 mg. A second dose may be taken at least two hours after the first if symptoms return, but do not exceed 200 mg (or 300 mg depending on the region's specific guidelines; 200 mg in the US, 300 mg in Australia) in a 24-hour period. The safety of treating more than four headaches in a 30-day period has not been established.