A cluster headache is one of the most painful types of headache. This uncommon condition often produces severe pain that occurs within minutes.

Cluster headaches are characterized by a sharp, penetrating, or burning pain affecting one side of the head. The pain often appears suddenly with little warning and often occurs in and around one eye or in the temple. The excruciating pain related to a cluster headache is often compared to the sensation of a hot poker being stuck in the eye. Others compare it to the feeling of the eye being pushed out of its socket. The condition may also produce a number of other symptoms including tearing of the eyes and nasal congestion.

According to the National Headache Foundation, cluster headaches affect less than 1 percent of people in the United States. About 85 percent of people affected by the condition are men, according to the American Council for Headache Education.

Cluster headaches differ from other types of headache because they occur in cyclical patterns (clusters). This type of headache occurs repeatedly every day at the same time, usually several times a day. One to four headaches a day is average. These frequent attacks may continue in a series of weeks or months (cluster periods), with each individual attack lasting an average of 45 to 90 minutes. Typically cluster periods last from two to 12 weeks. However, they can continue for more than a year. The temporary relief between attacks in a cluster period may last for a number of hours or continue for as long as a day.

The pain associated with a cluster headache often ends as abruptly as it begins, with a quick reduction in intensity. After the episode, patients are often pain-free but exhausted. The headache often goes into remission (period without headache) for some time until the pain returns. The remission period may last for months or possibly years.

Cluster headaches commonly occur at night. The abrupt onset of a cluster headache often occurs during the REM (rapid eye movement) or dreaming phase of sleep, or 90 minutes to three hours after a person falls asleep. 

Although frequency varies, most patients experience one or two cluster periods a year. In most cases, the cluster periods last between two and 12 weeks. In some people, however, cluster headaches occur for a year or more without going into remission.

The starting date and length of each cluster period is often very consistent. Many patients report that their cluster periods occur seasonally. It is also common for clusters to begin after the summer and winter solstices (the longest and shortest days of the year). Although cluster headaches occur in patterns for many people, over time they often become more frequent, less predictable and longer lasting. 

Pain usually develops on the same side of a person’s head for the duration of a cluster period. Many times, the headaches remain on the same side for a person’s entire life. Although it occurs rarely, pain may switch from one side of the head to another in subsequent cluster periods. It is extremely uncommon for pain to switch sides from headache to headache within the same cluster period.

People with cluster headaches may also have trigeminal neuralgia, a type of facial pain involving the trigeminal nerve. The combination of the two conditions is known as cluster-tic syndrome.

Cluster headaches do not pose a serious risk to a person’s overall health. However, it is a chronic condition that can cause debilitating pain. As a result, the condition can interfere with a person’s daily life and sleep cycle. In some cases, the severity of the pain becomes so unbearable that it causes people to attempt suicide.

Patients should discuss all serious or recurring headaches with their physician and seek medical attention when a headache:

• Starts suddenly
• Is severe or persistent
• Does not improve with treatment
• Disturbs sleep
• Occurs with activity
• Changes in pattern or intensity
• Is accompanied by other symptoms, such as drowsiness, vision changes, changes in movement or sensation, changes in alertness, nausea and vomiting

In some cases head pain may indicate a more serious underlying condition such as a brain tumor, stroke or aneurysm (a bulge in a weakened blood vessel with the potential to burst). As a result, patients should seek emergency medical treatment when:

• A headache is accompanied by unusual symptoms not experienced with previous headaches, including:
• • Speech problems
  • Vision abnormalities  (e.g., double vision)
  • Numbness or weakness
  • Fever
  • Stiff neck
  • Rash
  • Seizures
  • Mental confusion
    
    
• A headache occurs after a head injury
  
  
• A chronic headache intensifies with coughing, exertion, straining or sudden movement
  
  
• A new type of headache pain occurs (in those over age 50 or younger than 8)