What causes migraines?

Migraines are caused by abnormal activity in the brain. This may be triggered by a number of factors. Although the exact process in which this occurs is unknown, the disorder appears to involve blood vessels, nerve pathways and chemicals in the brain. Some researchers believe migraines are caused by imbalances in brain chemicals or changes in the trigeminal nerve in the face.

How do I know whether I have a migraine or another kind of headache?

A migraine is a severe, throbbing headache that is sometimes accompanied by other symptoms, such as nausea, sensitivity to light or sound, dizziness or chills. The pain is usually located at the side of the forehead. The most common form of headache, tension headache, consists of a dull, pressurelike pain over the head, neck and scalp. Usually it is not as severe as a migraine and does not involve other symptoms.

What other kinds of headaches are there?

There are more than 150 types of headaches on a list compiled by the International Headache Society. After tension headaches and migraines, the most common is a cluster headache. A cluster headache is a severe, chronic headache characterized by sharp, penetrating or burning pain on the side of the head. Unlike migraines and tension headaches, cluster headaches affect men more often than women.

Do symptoms usually occur before a migraine strikes?