Cluster headache by U.S. National Library of Medicine, National Institutes of HealthNational Institutes of Health
A cluster headache is a type of headache. It is one-sided head pain that may involve tearing of the eyes and a stuffy nose. Attacks occur regularly for 1 week to 1 year. The attacks are separated by pain-free periods that last at least 1 month or longer.
Cluster headaches may be confused with other common types of headaches such as migraines, sinus headache, and tension headache.
Scientists do not know exactly what causes cluster headaches. They seem to be related to the body's sudden release of histamine (chemical in the body released during an allergy response) or serotonin (chemical made by nerve cells). A problem in a small area at the base of the brain called the hypothalamus may be involved.
More men than women are affected. The headache can occur at any age, but are most common in adolescence and middle age. They tend to run in families.
Cluster headaches may be triggered by:
Alcohol and cigarette smoking
High altitudes (trekking, air travel)
Bright light (including sunlight)
Exertion (physical activity)
Heat (hot weather, hot baths)
Foods high in nitrites (such as bacon and preserved meats)
A cluster headache begins as a severe, sudden headache. The headache commonly strikes 2 to 3 hours after you fall asleep. But it can also occur when you are awake. The headache tends to happen daily at the same time of day. Attacks can last for months. Or they can alternate with periods without headaches (episodic). Or they can go on for a year or more without stopping (chronic).
Cluster headache pain is usually:
Burning, sharp, or steady
Felt on one side of the face from neck to temple, even involving the eye
At its worst within 5 to 10 minutes, with strongest pain lasting 30 minutes to 2 hours
When the eye and nose on the same side as the head pain is affected, symptoms can include:
Swelling under or around the eye (may affect both eyes)
Runny nose or stuffy nose on the same side as the head pain
Red, flushed face
More here: http://1.usa.gov/1sVnDrl
— with Norbee Pansuelo.