Caffeine is a stimulant that causes narrowing of blood vessels (vasoconstriction). Ergotamine is in a group of drugs called ergot alkaloids (ER-got AL-ka-loids). It works by narrowing the blood vessels around the brain. Ergotamine also affects blood flow patterns that are associated with certain types of headaches. Caffeine and ergotamine is a combination medicine used to treat or prevent a migraine type headache. This medication will only treat a headache that has already begun. It will not prevent migraine headaches or reduce the number of attacks. Caffeine and ergotamine should not be used to treat common tension headaches or any headache that seems to be different from your usual migraine headaches. Caffeine and ergotamine may also be used for purposes not listed in this medication guide.