Pain, swelling, bleeding, or bruising at the injection site may occur. Flushing, sensations of tingling/numbness/prickling/heat, weakness, drowsiness, or dizziness may occur. If any of these effects persist or worsen, notify your doctor or pharmacist promptly.
Remember that your doctor has prescribed this medication because he or she has judged that the benefit to you is greater than the risk of side effects. Many people using this medication do not have serious side effects.
This medication may raise your blood pressure. Check your blood pressure regularly and tell your doctor if the results are high.
Sumatriptan can commonly cause chest/jaw/neck tightness, pain, or pressure that is usually not serious. However, these side effects are like symptoms of a heart attack, which may include chest/jaw/left arm pain, shortness of breath, or unusual sweating. Get medical help right away if these or other serious side effects occur, including: fast/irregular heartbeat, fainting, severe stomach/abdominal pain, bloody diarrhea, signs of a stroke (such as weakness on one side of the body, trouble speaking, sudden vision changes, confusion).
Tell your doctor right away if any of these unlikely but serious side effects occur: blue fingers/toes/nails, cold sensation of hands/feet, hearing changes, mental/mood changes, seizures.
This medication may increase serotonin and rarely cause a very serious condition called serotonin syndrome/toxicity. The risk increases if you are also taking other drugs that increase serotonin, so tell your doctor or pharmacist of all the drugs you take (see Drug Interactions section). Get medical help right away if you develop some of the following symptoms: fast heartbeat, hallucinations, loss of coordination, severe dizziness, severe nausea/vomiting/diarrhea, twitching muscles, unexplained fever, unusual agitation/restlessness.
A very serious allergic reaction to this drug is rare. However, get medical help right away if you notice any symptoms of a serious allergic reaction, including: rash, itching/swelling (especially of the face/tongue/throat), dizziness, trouble breathing.
This is not a complete list of possible side effects. If you notice other effects not listed above, contact your doctor or pharmacist.
In the US - Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088 or at www.fda.gov/medwatch.
In Canada - Call your doctor for medical advice about side effects. You may report side effects to Health Canada at 1-866-234-2345.