Medication overuse headache
A rebound headache from frequent painkiller use.
Medication overuse headache (MOH), also called rebound headache, arises when painkillers are taken frequently to relieve headaches. It is a serious, disabling disorder and the third-most prevalent type of headache worldwide. MOH is a common cause of chronic daily headache and accounts for more than 20% of all headache-related disability globally.
Quick Facts
- Field
- Neurology
Facts from the source article.
Classification
Medication overuse headache is recognized in the International Classification of Headache Disorders. The term first appeared in the ICHD 2nd edition in 2004, where it was defined as a secondary headache emphasizing excessive drug intake. Subsequent revisions in 2005 and 2006 refined the criteria based on chronicity—headache on more than 15 days/month for more than three months—and drug classes. For ergotamine, triptans, opioids, and combination medications, intake on ≥10 days/month for >3 months is required; simple analgesics are overused when taken on ≥15 days/month for >3 months.
Causes
MOH occurs with frequent, chronic use of many pain or headache medications, including triptans, ergotamines, opioids, non-opioid analgesics (such as paracetamol and NSAIDs), combination medicines, or multiple taken together at a lower frequency. Common over-the-counter medications like Advil, Excedrin Migraine, and Cafergot can be involved. Dietary or medicinal caffeine appears to be a modest risk factor for chronic daily headache. A long history of headaches is a major risk factor; the condition is very rare in patients without recurrent headaches and never develops in those taking analgesics for non-headache pain. A family history of MOH may increase probability. Several mechanisms are theorized, including changes in cortical neuronal excitability, central sensitization of the trigeminal nerves, and alterations in serotonergic, dopaminergic, and endocannabinoid systems. A PET study showed decreased activity in the orbitofrontal cortex, also seen in substance abuse, suggesting a possible neurological susceptibility to addiction. The average time to develop MOH varies by medication: 1.7 years for triptans, 2.7 years for ergotamine, and 4.8 years for simple analgesics. The underlying mechanisms remain widely unknown, with research hampered by a lack of experimental research or suitable animal models.
Prevention
Patients with frequent headaches or migraine attacks should be considered candidates for preventive medications rather than encouraged to take more painkillers or rebound-causing medications. Preventive medications are taken daily, sometimes for many years or as briefly as six months. Effective preventives come from classes including neuronal stabilizing agents (anticonvulsants), antidepressants, antihypertensives, and antihistamines, such as amitriptyline, valproate, topiramate, and propranolol.
Treatment
MOH can be treated by stopping the overused medications, though limited evidence suggests this may be done without other preventive measures. The treatment of choice is abrupt drug withdrawal followed by prophylactic therapy. Discontinuation may cause initial worsening of headaches, nausea, vomiting, sleep disturbance, anxiety, and restlessness, lasting two to ten days; these symptoms are relieved by further intake of the overused medication, which can reinforce noncompliance. Gradual reduction may be necessary where physical dependence or rebound is possible. Abruptly discontinuing butalbital can induce seizures, though simple over-the-counter analgesics can be stopped safely without medical supervision. A long-acting analgesic/anti-inflammatory such as naproxen (500 mg twice a day) can ease headache during withdrawal. Two months after withdrawal, patients typically notice a marked reduction in headache frequency and intensity. Withdrawal is performed differently across countries; most physicians prefer inpatient programs, but outpatient withdrawal may be effective in uncomplicated patients without important comorbidities, not overusing opioids or ergotaminics, and at their first detoxification attempt. The choice of preventive agent should be based on the primary headache type, side-effect profile, comorbidities, patient preferences, and previous experiences. Up to 45% of patients relapse, reverting to overuse of symptomatic drugs.
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