The most common type of severe headache is caused by migraine. It is very common, and it is estimated that about 10% of the population suffers from migraine. It is about three times more common in women. It is estimated that in the USA alone, 92 million workdays are lost to migraine attacks at a cost of $11,000,000,000. Migraine is a illness affecting the brain. Severe headache is only one manifestation of a migraine attack. Most patients with migraines also have nausea and photophobia (light hurts their eyes) as well as other symptoms. The headache is usually throbbing, severe, and often is on one side of the head (hemicranial, from which the word migraine is derived). The links below will inform you about migraine. Diagnosis of Migraine Cause of Migraine Who gets Migraine Treatment of Migraine How to get the help you need