Frequent use of symptomatic headache drugs may induce medication overuse headache. In primary care settings, medication overuse headache is the third common diagnosis of headache, next to migraine and tension-type headache. The pathophysiologic mechanisms are unknown. It is a severely disabling condition that has a huge economic impact on society. Treatment includes complete drug withdrawal, and the prognosis is good. Preventive measures and providing information to the patients are very important.