Sumatriptan Nasal Spray is used to treat migraine attacks by narrowing swollen blood vessels around the brain and relieving headache, nausea and sensitivity to light and sound. Use the spray as soon as your migraine starts, exactly as prescribed. Common side effects include a bitter taste, dizziness, drowsiness and nasal irritation. Do not use it to prevent migraines, and seek urgent medical advice if you experience chest pain or severe allergic reactions.