Evidence from 13 randomized trials of the treatment of migraine in 4,222 patients and tens of thousands of patients in prevention of recurrent attacks supports the use of high dose aspirin from 900 to 1,300 milligrams to treat acute migraine as well as low dose daily aspirin from 81 to 325 milligrams to prevent recurrent attacks. Aspirin is available without a prescription, is inexpensive, and has a relatively favorable side-effect profile compared to alternative more expensive medications.