By definition, chronic daily headaches occur 15 or more days per month for at least 3 months. But, as the name suggests, some headache patients suffer almost daily with headaches.
Risk factors for developing CDH:
Previous history of frequent headaches
History of minor head trauma
Association with psychiatric disorders, such as depression and anxiety
Major life changes
CDH does not fit into any specific criteria, but the major primary headaches can become CDH. These include:
Chronic migraine (CM)
Chronic tension-type headache (CTTH)
New daily persistent headache (NDPH)
Medication overuse headache (MOH)
Chronic migraine Patients who suffer from episodic migraine can develop chronic migraines, where the headaches occur for more than 8 days per month. The other characteristics of the pain and associated symptoms are similar to the episodic migraine.