| Chronic daily headaches of long duration are characterized by headache duration ≥4 hours a day with headaches occurring ≥15 days per month for >3 months | |
| Chronic tension-type headache: | Bilateral, gradual onset, muscle tenderness common |
| Chronic migraine: | Daily or near-daily headaches of low to moderate intensity and mild migrainous features with superimposed severe intensity headaches with more prominent migrainous features |
| Medication overuse headache: | Usually preceded by an episodic headache disorder, typically migraine or tension-type headache, that has been treated with frequent and excessive amounts of acute symptomatic medications; often manifests as a headache that is present or develops upon awakening |
| New daily persistent headache: | Sudden onset, usually bilateral, typically unresponsive to treatment |
| Hemicrania continua: | Strictly unilateral, unremitting without pain-free intervals but with variable intensity, autonomic features ipsilateral to the side of pain, responsive to indomethacin |
