Medication Overuse Headache.

Medication overuse headache (MOH) is defined as a new or worsening headache occurring more than 15 days a month in people with a pre-existing primary headache that develops as a result of regular overuse of acute headache treatments. MOH is a common secondary headache disorder with an estimated prevalence of 1% to 5%. The presence of a pre-existing primary headache disorder is the main risk factor for MOH.