An overview of the classification, causes, and treatment of headache.

Headache has been documented as the reason for approximately 18 million office visits per year in the United States, and may be the most prevalent central nervous system condition for which patients consult doctors. The author presents an overview of the literature on classification, causes, and treatment of headache, including uncertainties about diagnostic criteria for migraine and about differentiation of migraine from muscle contraction headache. He discusses treatment of headache in relation to management of the acute attack, avoidance of trigger factors, and pharmacological and nonpharmacological prophylaxis.