The treatment of migraine may be acute (abortive) or preventive (prophylactic). Preventive therapy is used in an attempt to reduce the frequency, duration, or severity of attacks. Additional benefits include enhancing the response to acute treatments, improving a patient's ability to function, and reducing disability. The major medication groups for preventive migraine treatments include anticonvulsants, antidepressants, ß-adrenergic blockers, calcium channel antagonists, serotonin antagonists, botulinum neurotoxins, nonsteroidal anti-inflammatory drugs, and others (including riboflavin, magnesium, and petasides). If preventive medication is indicated, the agent should be chosen from one of the first-line categories, based on the drug's relative efficacy in double-blind, placebo-controlled trials, its side effect profile, and the patient's preference, as well as coexistent and comorbid conditions.