What Is a Cluster Headache?

Cluster headaches produce severe pain. Named because they occur in clusters, these rare headaches can go away for weeks or years or occur several times a day.

When compared to other kinds of headaches, cluster headaches are, thankfully, rare. But for those who do experience these headaches, cluster headaches can be extremely painful and downright miserable. In fact, people with cluster headaches often describe the pain as stabbing and unbearable.

This type of headache gets its name from the fact the pain comes in "clusters," usually at the same time of day, especially at night. Cluster headaches can hit multiple times a day (each “attack” lasts about one to three hours) and persist for days or weeks. They may also go into remission for weeks, months, or even years, explains the National Center for Advancing the Translational Sciences, part of the National Institutes of Health (NIH).

There are medications to help relieve the pain and prevent or reduce cluster headache episodes. Yet cluster headaches are sometimes confused with other types of headaches (especially migraines). It’s important to be under the care of a doctor who is experienced with diagnosing and treating cluster headaches.

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Cluster headache symptoms are different

Although cluster headaches can hit at any age, they most often first occur between the ages of 20 and 50. Men are more likely to have this type of headache than women.

They are far more severe than tension headaches. Although sometimes confused with migraines, cluster headaches have different symptoms and different treatments. They may also be more severe than migraines.

• Symptoms include pain on one side of the head, typically behind or around one eye, the NIH notes.
• Unlike the throbbing pain of migraines, cluster headache pain is sharp and feels piercing.
• The nose and the eye on the side of the head where the pain is felt often become red and swollen.
• The affected eye may be bloodshot and watery with a drooping eyelid.
• Your nose may run.
• Some people are restless and even agitated during a cluster headache.

Other symptoms can include:

• Nausea
• Changes in the heart rate and blood pressure
• Feeling hypersensitive to sound, smells, and light

These headache attacks, called cluster periods, usually occur daily over weeks or months and then disappear for months or even years before they return. The exception, the National Organization for Rare Disorders (NORD) explains, are chronic cluster headaches. This type, which affects less than 20 percent of cluster headache patients, continues for a year a more, without relief except for a few days or weeks at a time.

What causes cluster headaches?

Researchers have not identified the underlying cause of cluster headaches, but they have made progress in understanding the condition. Cluster headache pain has been linked to the dilation of blood vessels that create pressure on the trigeminal nerve, according to NORD.

The NIH notes the release of histamine (normally released in the body during an allergic response) or serotonin (a neurochemical made by nerve cells) may play a role in the development of cluster headaches.

Several clues suggest cluster headaches are the result of an abnormality in the body’s “internal clock,” the circadian rhythm. In most cases, for example, cluster headaches occur more often at night than daytime, and more often in the spring and fall. Individuals tend to experience their cluster headaches at the same time every day, too.

A study, published in Cephalalgia, the journal of the International Headache Society, backs up this idea that cluster headaches are tied to the circadian rhythm. Neuroscientists found about 82 percent of people with chronic cluster headaches reported their attacks usually occurred the same time, each day they experienced a cluster headache.

What’s more, recent studies using positron emission tomography (or PET) scans have revealed activity in the hypothalamus (the part of the brain responsible for the body’s circadian rhythm) during cluster headaches. This backs up a previous hypothesis that the hypothalamus somehow is the “generator” driving cluster headaches, NORD explains.

There is help for cluster headaches

Cluster headaches, especially the chronic type, can be debilitating, negatively effecting your quality of life and resulting in missed work. Research published in Neurology, the journal of the American Academy of Neurology, found people with cluster headaches miss, on average, twice as much time from work than people with other health conditions.

Although there is no cure for these headaches, the good news is spontaneous remissions do occur, the National Institutes of Health points out. Appropriate treatment can relieve symptoms and sometimes prevent the headaches from developing.

There is no one-size-fits-all medication for people with cluster headaches, however. So, if you believe you may have cluster headaches — or if you are struggling with them and have not found significant relief — it’s a good idea to see a neurologist who has experience diagnosing and treating the condition.

Treatment often includes triptan drugs (given as a pill, nasal spray, or injection) to quickly relieve acute headache pain. Oxygen inhalation therapy can also be helpful.

Ergotamine and corticosteroids (medications that include prednisone and dexamethasone) may be prescribed, depending on your individual case, to break the cluster cycle during the headache phase. The drugs are then tapered off when the headache cluster ends. Verapamil, a calcium channel blocker used to treat high blood pressure, can help prevent cluster headaches or, at least, decrease the frequency and pain level of attacks in many people.

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