Cluster headaches are extremely painful headaches that begin unexpectedly, are short-lived and occur several times a day.
The headaches affect one side of the head and are often felt behind or around the eye.
Sleep is often disrupted as the headache can cause you to wake up at the same time each night. The eye on the affected side often becomes red and watery and your nose may become blocked or runny on the affected side (see Symptoms, above, for more information).
It is not known what causes cluster headaches, but they are more common in autumn and spring. In some people, they are triggered by drinking alcohol or an extreme increase in temperature (such as from exercising in hot weather).
Who is affected?
Cluster headaches are rare and affect around one in 1,000 people. Anyone can be affected, but approximately eight out of 10 people who have them are men and most are smokers.
How long do they last?
Each cluster headache lasts between 15 minutes and three hours (but often less than an hour). You will usually get one to three cluster headaches every day for several weeks or months before the attacks subside. More headaches may then develop some months later.
Outlook
Although cluster headaches can interfere with everyday life, they are not life-threatening and can be relieved with a medication called sumatriptan or with oxygen therapy (see Treatment, above). You can take medicines to prevent cluster headaches from developing.
