Contrary to popular belief, a cluster headache is not simple a collection of headaches that come in a bunch together. A cluster headache is a type of headache which is relatively short-lived (compared with migraine) lasting usually between 20 minutes and two hours. It is always one-sided and is associated with symptoms such as a stuffy nose on one side, tearing, an enlarged pupil, or a droopy lid.
The headaches tend to occur several to many times a day for a period of days to weeks, and then disappear for a variable amount of time, usually weeks to months. Treatments for cluster differ significantly from treatments for other headache types. Clusters are, by reputation, some of the most painful headaches imaginable. It is important to have a treatment plan in place before a cluster begins.