The purpose of this study is to evaluate the effectiveness and safety of almotriptan malate (AXERT®) 12.5 milligram tablets compared with placebo for the acute treatment of migraine headache at the earliest onset of headache pain. Almotriptan malate (AXERT®) is approved for the treatment of migraine headache, with or without aura, in adults. Patients in this study will take either almotriptan or placebo oral tablets for 3 consecutive migraine headaches.