Rizatriptan is a headache medicine that narrows the blood vessels around the brain. Rizatriptan also reduces substances in the body that can trigger headache pain, nausea, sensitivity to light and sound, and other migraine symptoms. Rizatriptan is used to treat migraine headaches. Rizatriptan will only treat a headache that has already begun. It will not prevent headaches or reduce the number of attacks. Rizatriptan should not be used to treat a common tension headache, a headache that causes loss of movement on one side of your body, or any headache that seems to be different from your usual migraine headaches. Use this medication only if your condition has been confirmed by a doctor as migraine headaches. Rizatriptan may also be used for purposes not listed in this medication guide.