Chronic daily headache is one of the most challenging headache syndromes encountered by physicians.

Most commonly, chronic daily headaches occur when migraine headaches become "transformed." That is to say, migraine headaches become more and more frequent over time until they occur on a daily basis. Episodic tension-type headaches and chronic tension-type headaches also can "transform" into chronic daily headaches. More often than not, chronic daily headaches are exacerbated by abuse of medications for headaches. This is called "analgesic rebound headache."

There are several effective treatments available for chronic daily headaches. The most effective treatment probably is intravenous DHE, which usually requires admission to the hospital.