Medication overuse headache

The IHS describes medication overuse headache (MOH) as an interaction between a therapeutic agent used excessively and a susceptible patient (eg, overuse of acute agents causing headache in a headache-prone patient).⁵⁰ For a diagnosis of MOH, patients must have headache on at least 15 days per month that:

• Has developed or markedly worsened over the course of a minimum 3-month history of overusing acute medications
• Resolves or reverts to its previous pattern within 2 months of discontinuing medication overuse.⁵⁰

The criteria for MOH are evolving. The most recent revision does not require headache resolution or return to the previous headache pattern to confirm the diagnosis.⁵¹

The prevalence of MOH in the general population is about 1% among adults in Europe, North America, and Asia.^52,53 In some headache centers, up to two thirds (64%) of patients are affected.⁵⁴ Providers should be alert for MOH in patients reporting frequent headache attacks, as overuse of symptomatic migraine drugs and/or analgesics is the most common cause of migraine-like and tension-type-like headaches on at least 15 days per month.⁵⁰

The etiology of MOH remains unclear. In some cases, the interaction between a therapeutic agent and susceptible patient may originate with the patient taking an immediate-relief medication (or medications) at the slightest hint of an attack. This approach can evolve into a habit of treating in anticipation of headache, when no pain exists. Eventually, the headache/medication cycle becomes self-sustaining, head pain becomes chronic, and treatment with immediate-relief drugs becomes the cause of head pain. Signs of drug-seeking behavior may be evident in a small subset of MOH patients.⁵⁵

It has been suggested that adding caffeine to headache remedies can increase the likelihood of developing MOH. But the evidence shows that:

• Caffeinated analgesics are not more likely to be overused than single-agent analgesics.⁵⁶
• Immediate-relief medications do not cause MOH in patients not prone to headache).⁵⁷
• Caffeine has never been implicated as the sole agent involved in MOH.⁵⁸

One study of CDH patients reported that almost 90% of subjects overused single-agent NSAIDs, nearly 40% overused APAP, and only about 5% of subjects were found to be taking caffeinated analgesics.⁵⁹ Recent assessments confirm that patients with CDH are not more likely than episodic headache patients to be using or have a history of using caffeinated combinations.60 Because any excessively used immediate-relief medication can cause MOH,^61-65 multiple subtypes of MOH have been established, including ergotamine overuse, triptan overuse, simple analgesic overuse, opioid overuse, and combination analgesic overuse.⁵⁰

Treatment of MOH consists of withdrawing the offending agent as soon as the problem is detected and providing general supportive measures (such as fluid replacement, repetitive parenteral pain-control treatment, or treatment of withdrawal symptoms)⁵⁶ through a period of increased headache intensity and frequency. Refractory cases may require in-patient care. Once the cycle of medication has been broken, patients tend to return to their pre-MOH headache condition.⁶⁶ However, this transition may take a significant amount of time and may never occur.⁵¹ In all cases, patients must be aggressively educated about appropriate use of analgesic medications before reintroducing drug therapy.