|8.2||Medication-overuse headache (MOH)||G44.41 or G44.83|
|Previously used terms||Rebound headache, drug-induced headache, medication-misuse headache|
- Headache1 present on ≥15 days/month fulfilling criteria C and D
- Regular overuse2 for ≥3 months of one or more drugs that can be taken for acute and/or symptomatic treatment of headache3
- Headache has developed or markedly worsened during medication overuse
- Headache resolves or reverts to its previous pattern within 2 months after discontinuation of overused medication4
- The headache associated with medication overuse is variable and often has a peculiar pattern with characteristics shifting, even within the same day, from migraine-like to those of tension-type headache.
- Overuse is defined in terms of duration and treatment days per week. What is crucial is that treatment occurs both frequently and regularly, ie, on 2 or more days each week. Bunching of treatment days with long periods without medication intake, practised by some patients, is much less likely to cause medication-overuse headache and does not fulfil criterion B.
- MOH can occur in headache-prone patients when acute headache medications are taken for other indications.
- A period of 2 months after cessation of overuse is stipulated in which improvement (resolution of headache, or reversion to its previous pattern) must occur if the diagnosis is to be definite. Prior to cessation, or pending improvement within 2 months after cessation, the diagnosis 8.2.8 Probable medication-overuse headache should be applied. If such improvement does not then occur within 2 months, this diagnosis must be discarded.
Medication-overuse headache is an interaction between a therapeutic agent used excessively and a susceptible patient. The best example is overuse of symptomatic headache drugs causing headache in the headache-prone patient. By far the most common cause of migraine-like headache occurring on -15 days per month and of a mixed picture of migraine-like and tension-type-like headaches on -15 days per month is overuse of symptomatic migraine drugs and/or analgesics. Chronic tension-type headache is less often associated with medication overuse but, especially amongst patients seen in headache centres, episodic tension-type headache has commonly become a chronic headache through overuse of analgesics.
Patients with a pre-existing primary headache who develop a new type of headache or whose migraine or tension-type headache is made markedly worse during medication overuse should be given both the diagnosis of the pre-existing headache and the diagnosis of 8.2 Medication-overuse headache.
The diagnosis of medication-overuse headache is clinically extremely important because patients rarely respond to preventative medications whilst overusing acute medications.