What is Medication Overuse Headache?
Medication overuse headache (MOH) is a secondary headache disorder that develops when patients with a pre-existing primary headache disorder (like migraine or tension-type headache) experience headaches on ≥15 days per month for at least 3 months as a direct consequence of regularly overusing acute headache medications. 1
Defining Characteristics
MOH represents a paradoxical worsening of headache frequency caused by the very medications intended to treat headaches. 1 The condition affects approximately 1% of the general population but is substantially more common among patients with chronic migraine, where it accounts for roughly two-thirds of cases. 1, 2
Medication Overuse Thresholds
The diagnosis depends on both headache frequency and specific medication use patterns:
- ≥15 days per month for NSAIDs, acetaminophen, or combination analgesics 1
- ≥10 days per month for triptans, ergotamines, or opioids 1
- The overuse pattern must persist for more than 3 months 1
- Headaches must occur on ≥15 days per month during this period 1
Clinical Presentation and Pathophysiology
The headache phenotype in MOH depends on the underlying primary headache disorder and the specific type of overused medication. 2 Patients typically have a long history of episodic primary headache that transforms over years or decades into a pattern of daily or near-daily headaches following chronic overuse of symptomatic medications. 3
The condition can only be confirmed retrospectively after successful withdrawal of the overused medication, requiring observation for 2-3 months to document improvement in headache frequency. 1 This diagnostic requirement distinguishes MOH from chronic migraine, though these conditions frequently coexist and require different management approaches. 1
Medications at Highest Risk
While any acute headache medication can cause MOH when overused, certain drug classes carry elevated risk:
- Opioids and barbiturates have the highest risk for MOH development and dependency, with higher relapse rates after treatment 1, 2
- Triptans are considered moderate risk when used ≥10 days per month 1
- Combination analgesics containing caffeine or butalbital pose significant risk 1
Primary Prevention Strategy
Patients should be educated that using any acute headache medication more than twice weekly (approximately 8-10 days per month) can increase headache frequency and may lead to daily headaches. 1 Preventive therapy should be initiated in patients experiencing ≥2 headache days per week to reduce the risk of developing MOH. 1
Common Clinical Pitfalls
The most critical error is failing to recognize MOH as a distinct entity from the underlying primary headache disorder. 1 Clinicians frequently confuse chronic migraine with MOH, yet these conditions require fundamentally different initial management—MOH requires medication withdrawal first, while chronic migraine may be treated with preventive therapy without mandatory withdrawal. 1
Another common mistake is continuing to prescribe acute medications without addressing the overuse pattern, which perpetuates the cycle of medication dependence and worsening headache frequency. 2, 4