Do not take Sumatriptan if you have a hypersensitivity to sumatriptan or to any of its excipients.
Do not take Sumatriptan if you have previously experienced a myocardial infarction, ischaemic heart disease, cerebrovascular accident (CVA) or transient ischaemic attack (TIA), or severe hepatic impairment.
Disclose your current medication with your doctor, as sumatriptan cannot be taken with other migraine or headache medicines, antidepressants called MAOIs (monoamine oxidase inhibitors and other antidepressants. Sumatriptan must not be used within 2 weeks of discontinuation of therapy with monoamine oxidase inhibitors.
If you experience any of the severe side effects mentioned below you are recommended to cease taking sumatriptan and contact a healthcare professional. These symptoms include:
• The feeling of tightness or tingling in your face, arms, legs or chest
• Unusual feelings of heaviness in your face, arms, legs or chest
• Feelings of warmth or cold in your face, arms, legs or chest

Do not take Sumatriptan with St John's wort as this can increase your risk of serotonin syndrome.