Medication overuse headache.

PURPOSE OF REVIEW Medication-overuse headache (MOH) is a chronic daily headache in which acute medications used at high frequency cause transformation to headache occurring 15 or more days per month for 4 or more hours per day if left untreated. MOH is a form of US Food and Drug Administration-defined chronic migraine. This review will describe (1) MOH clinical features and diagnosis, (2) pathophysiology and structural and functional MOH brain changes, and (3) prevention and treatment of MOH. RECENT FINDINGS MOH causes structural and functional brain changes. Any butalbital or opioid use increases the risk of transforming episodic into chronic migraine (sometimes referred to as chronification). The American Migraine Prevalence and Prevention Study demonstrated that transformation is most likely to occur with 5 days of butalbital use per month, 8 days of opioid use per month, 10 days of triptan or combination analgesic use per month, and 10 to 15 days of nonsteroidal anti-inflammatory use per month. Acute migraine treatment should be limited to 2 or fewer days per week, and opioids and butalbital should be avoided.Treatment of MOH consists of combining prophylaxis, 100% wean of overused acute medications, and provision of new acute medications, strictly limiting use to 2 or fewer days per week. Wean can be done slowly in an outpatient setting or it can be done abruptly, sometimes requiring hospitalization with medicine bridges. SUMMARY MOH development is linked to baseline frequency of headache days per month, acute medication class ingested, frequency of acute medications ingested, and other risk factors. Using less effective or nonspecific medication for severe migraine results in inadequate treatment response, with redosing and attack prolongation, frequently leading to chronification. Use of any barbiturates or opioids increases the transformation likelihood.Patients with MOH can usually be effectively treated. The first step is 100% wean, followed by establishing preventive medications such as onabotulinumtoxinA or daily prophylaxis and providing acute treatment for severe migraine 2 or fewer days per week. Slow wean or quick termination of rebound medications can be accomplished for most patients on an outpatient basis, but some more difficult problems may need referral for multidisciplinary day hospital or inpatient treatments.