Chronic headaches and medication overuse.

Chronic headaches represent a significant burden for the affected individuals and for the society, and a major challenge for successful care. Among the various types of chronic headaches, those that are associated with medication overuse (medication-overuse headache, MOH) are of particular importance because of the large proportion of patients who complain of this condition and their poor outcome. Most patients with MOH had migraine as primary headache. Practically, almost all drugs used for the symptomatic relief of migraine, including triptans and analgesics can cause MOH. Although the pathophysiology of MOH is unknown, recent studies hypothesize that plastic changes in specific pain areas of the central nervous system are main contributors to establishing MOH. Not infrequently, drug overuse is associated with habituation and failure of previously effective medications. Finally, treatment of MOH is poorly evidence based and mostly relies on clinical experience and belief.