Chronic migraine and medication-overuse headache

Count headache days: 15 or more a month for over 3 months makes migraine chronic, and frequent acute-drug use adds medication-overuse headache. Vascular disease rules out triptans, and indomethacin response defines hemicrania continua.

1. Chronic migraine is a day-count diagnosis. ICHD-3 requires headache on at least 15 days a month for more than 3 months, with migraine features on at least 8 of those days ¹.
2. Medication overuse is a second, coexisting diagnosis. Medication-overuse headache needs headache on 15 or more days a month in a person with a pre-existing headache disorder, plus regular overuse of acute drugs for more than 3 months; both diagnoses are given when both criteria are met ¹².
3. Thresholds differ by drug class. Triptan overuse is defined as use on 10 or more days a month, a lower bar than the 15 days used for simple analgesics ³. The triptan label lists ergotamine, triptans, opioids and combinations used 10 or more days a month as possible causes ⁴.
4. Triptans are vasoconstrictors with cardiac contraindications. The zolmitriptan label lists ischemic heart disease, coronary vasospasm, uncontrolled hypertension, prior stroke or TIA, hemiplegic or basilar migraine and peripheral vascular disease as contraindications ⁴.
5. Gepants avoid the vascular contraindication. Ubrogepant, a CGRP receptor antagonist, is contraindicated only with strong CYP3A4 inhibitors and hypersensitivity; strong CYP3A4 inducers should be avoided, and the label advises blood pressure monitoring ⁵.
6. OnabotulinumtoxinA is for chronic, not episodic, migraine. It is labeled for prophylaxis in adults with headache on at least 15 days a month lasting 4 hours or longer; benefit in episodic migraine (14 or fewer days) is not established ⁶.

A continuous, strictly one-sided headache with autonomic flares is not migraine until proven otherwise: ICHD-3 hemicrania continua requires an absolute response to therapeutic indomethacin ⁷.

• Chronic migraine and medication-overuse headache are coded together when both are met; one does not exclude the other ².
• Triptan-overuse threshold: 10 or more days a month for more than 3 months ³.
• Triptans are contraindicated within 24 hours of another triptan or an ergot and within 2 weeks of an MAO-A inhibitor ⁴.
• Ubrogepant may be repeated after at least 2 hours, to a maximum of 200 mg in 24 hours ⁵.
• OnabotulinumtoxinA for chronic migraine: 155 units as 5-unit injections across seven head and neck muscles, repeated every 12 weeks ⁶.
• ICHD-3 advises an initial indomethacin trial of at least 150 mg daily, increased up to 225 mg if needed, to confirm hemicrania continua ⁷.
• Paroxysmal hemicrania is also indomethacin-responsive but causes discrete 2–30 minute attacks without a continuous background ⁸.

• Excluding medication-overuse headache because the patient already has chronic migraine ².
• Using the 15-day analgesic threshold for triptans ³.
• Offering onabotulinumtoxinA for episodic migraine ⁶.
• Giving a triptan or ergot to a patient with coronary disease when a gepant is available ⁴⁵.