Chronic migraine is a disorder in which a person has migraine headaches on 15 or more days each month. The cause isn't clear.

Some research suggests that it may be due to changes in parts of the brain that control pain.

This disorder isn't due to frequent use of painkillers. Treatment of chronic migraine may include certain antidepressants, anti-seizure medications or cardiovascular drugs. However, even with such treatment, migraines may persist.