Imitrex is a migraine treatment containing the active ingredient sumatriptan. It is prescribed to patients who have regular migraine attacks. Sumatriptan, which is widely used in generic drug copies of Imitrex, can help reduce the effect of migraine if taken before the headache starts. Imitrex tablets can also help reduce symptoms such as upset stomach, nausea and light and noise sensitivity that come with a migraine attack. You can buy generic Imitrex online in tablet and nasal spray forms.