Cluster headaches, which occur in cyclical patterns or clusters, are one of the most painful types of headache. A cluster headache commonly awakens you in the middle of the night with intense pain in or around one eye on one side of your head.
Bouts of frequent attacks, known as cluster periods, can last from weeks to months, usually followed by remission periods when the headaches stop. During remission, no headaches occur for months and sometimes even years.
Fortunately, cluster headache is rare and not life-threatening. Treatments can make cluster headache attacks shorter and less severe. In addition, medications can reduce the number of cluster headaches.
Common signs and symptoms
A cluster headache strikes quickly, usually without warning, although you might first have migraine-like nausea and aura. Common signs and symptoms during a headache include:
People with cluster headache, unlike those with migraine, are likely to pace or sit and rock back and forth. Some migraine-like symptoms — including sensitivity to light and sound — can occur with a cluster headache, though usually on one side.
Cluster period characteristics
A cluster period generally lasts from six to 12 weeks. The starting date and the duration of each cluster period might be consistent from period to period. For example, cluster periods can occur seasonally, such as every spring or every fall.
Most people have episodic cluster headaches. In episodic cluster headaches, the headaches occur for one week to a year, followed by a pain-free remission period that can last as long as 12 months before another cluster headache develops.
Chronic cluster periods might continue for more than a year, or pain-free periods might last less than one month.
During a cluster period:
The pain usually ends as suddenly as it began, with rapidly decreasing intensity. After attacks, most people are pain-free but exhausted.
When to see a doctor
See your doctor if you’ve just started to have cluster headaches to rule out other disorders and to find the most effective treatment.
Headache pain, even when severe, usually isn’t the result of an underlying disease. But headaches can occasionally indicate a serious underlying medical condition, such as a brain tumor or rupture of a weakened blood vessel (aneurysm).
Additionally, if you have a history of headaches, see your doctor if the pattern changes or your headaches suddenly feel different.
Seek emergency care if you have any of these signs and symptoms:
The exact cause of cluster headaches is unknown, but cluster headache patterns suggest that abnormalities in the body’s biological clock (hypothalamus) play a role.
Unlike migraine and tension headache, cluster headache generally isn’t associated with triggers, such as foods, hormonal changes or stress.
Once a cluster period begins, however, drinking alcohol may quickly trigger a splitting headache. For this reason, many people with cluster headache avoid alcohol during a cluster period.
Other possible triggers include the use of medications such as nitroglycerin, a drug used to treat heart disease.
Risk factors for cluster headaches include: