Preventive treatment of migraine.

Migraine preventive therapy, even in the absence of a headache, is given in an attempt to reduce the frequency, duration, or severity of attacks. Circumstances that might warrant preventive treatment include disabling migraine attacks, the overuse of acute medications or failure of or contraindication to acute medications, troublesome side effects from medication, hemiplegic migraine, or very frequent headaches (more than 2 a week). The major medication groups for preventive treatment include anticonvulsants, antidepressants, b-adrenergic blockers, calcium channel antagonists, serotonin antagonists, neurotoxins, nonsteroidal anti-inflammatory drugs, and others. If preventive medication is indicated, the agent preferentially should be chosen from one of the first-line categories, based on the drug's side-effect profile and the patient's coexistent and comorbid conditions.