Definition

A headache is a pain in the head. A headache can be caused by some other physical disorder, or it may be a disorder in and of itself.

Description

There are three major types of headaches: tension (or stress), migraine, and cluster. A tension headache is caused by the tightening of muscles in the neck and head. A migraine headache occurs when blood vessels in the brain dilate (swell up). Cluster headaches are characterized by very severe pain.

Tension headaches are probably the most common form of the disorder. Nearly everyone has a tension headache from time to time. Migraine headaches are less common. About 18 percent of American women and 6 percent of American men experience migraine headaches on a relatively regular basis. Cluster headaches are fairly rare. Less than 0.5 percent of Americans experience cluster headaches. Men make up 80 percent of all cluster headache sufferers.

Approximately forty to...