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Cluster Headache

Histamine Cephalgia, Horton's Headache, Basilar Migraine, Ciliary Neuralgia, Migrainous Neuralgia

What is Cluster headaches?

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)

Types and differences of cluster headaches

According to the International Classification of Headache Disorders, there are two groups of cluster headaches, based on the lengths of the cluster periods and remission periods:
  • Episodic. This term may be used to describe cluster headaches occurring daily in periods of one week to one year, followed by remission lasting at least one month before the development of another cluster period.
  • Chronic. This term may be used to describe cluster headaches occurring daily for more than a year, with no remission or with pain-free phases lasting less than one month.
According to the National Headache Foundation, about 10 to 20 percent of people who experience cluster headaches have the chronic form. Although chronic cluster headache may develop after a phase of episodic attacks, it may also develop in people without a history of headaches. Rarely, patients may also experience alternating phases of chronic and episodic headache.

How is it diagnosed?

Cluster headaches can be distinguished from other types of headache because they produce a distinctive type of pain and occur in a unique pattern. As the name suggests, they come in “clusters,” with severe pain followed by remission periods. Physicians can use these symptoms to help diagnose cluster headaches.

During an evaluation for cluster headaches, physicians typically take the patient’s medical history and perform a physical examination. Information provided during these steps can help physicians determine whether a patient’s symptoms are the result of a cluster headache or an underlying medical condition (e.g., brain tumor, aneurysm).

While collecting a patient’s medical history, physicians may ask the patient to describe symptoms. Questions in a pain assessment may focus on the characteristics of the pain, including its severity, location, frequency and duration. The patient will also be asked to describe any symptoms that accompany the pain. During the physical exam, physicians may detect one-sided eyelid drooping or reduced pupil size as part of a neurological exam.

There is no particular test to diagnose cluster headaches, so medical history and physical examination are the only way to diagnose this condition. Other tests may be performed to rule out other serious causes of head pain. Physicians may use a number of methods to determine the cause of the chronic or recurrent head pain. These include:

MRI (magnetic resonance imaging)

MRIs use a powerful magnetic field to create images of structures and organs within the body, allowing a computer to produce clear cross-sectional or three-dimensional images. This test may be ordered to examine the brain and rule out aneurysm and a number of other serious causes.

CAT scan (computed axial tomography)

This test allows for multiple x-rays to be taken from different angles around the patient. A computer analyzes the “slices” or cross-sectional images. Frequently after the first set of images is taken, the patient receives an intravenous (I.V.) injection of a contrast medium (dye) to better outline the body parts. Then a second set of images is taken. This test may be ordered to examine the brain and rule out aneurysm and a number of other serious causes of pain.
If trigeminal neuralgia or another cranial neuralgia is also suspected, the patient may undergo a neurological exam and testing such as electromyography (EMG) and nerve conduction velocity (NCV) studies.

How is Cluster headaches treated?

There are a number of treatment options available for cluster headaches. Although cluster headaches cannot be cured, treatments aim to relieve symptoms, shorten the headache period and prevent future episodes.

Although they do not cure cluster headaches, prescription and over-the-counter medications may also be used to prevent headaches, stop the progression of headaches and relieve symptoms.

Pure oxygen may be recommended as a treatment method for cluster headaches, particularly those that occur at night. Administered through a breathing mask, supplemental oxygen can provide pain relief within 15 minutes. However, this type of treatment may be inconvenient, because patients must carry an oxygen cylinder and regulator with them.

A combination of headache medications may be used to treat cluster headaches and to prevent future headaches. Treating an existing headache is called acute or abortive therapy. These medications include antimigraine medications, which include:
  • Triptans, which are a type of serotonin agonist. They may be injected or taken orally or nasally. These medications may not be prescribed for patients with certain conditions, including high blood pressure, angina and some liver conditions.
  • Ergotamine or ergotamine derivatives. Drugs that constrict dilated blood vessels, which often occur with headaches. This medication may be used to prevent headaches as well, but side effects can be severe (e.g., nausea, confusion, vision changes) and is often not used for more than two or three weeks. These drugs may be used with others, such as isometheptene, which reduces throbbing pain.
Other forms of medication used for acute pain relief include local anesthetics. Acute medications should be taken as soon as the attack begins. They are effective in treating the rapidly peaking pain associated with cluster headaches because they are fast-acting.

Over-the-counter drugs such as aspirin and ibuprofen are not effective in treating cluster headaches because they take too long to take effect. In most cases, the headache has disappeared by the time these medications begin to work.

There are also a number of medications used to reduce the frequency and severity of cluster headaches and increase the effectiveness of acute medications. These preventive drugs are used in short-term and long-term management strategies. Short-term drugs are fast-acting but can cause serious or undesirable side effects. The long-term medications take longer to work but can be used safely for a longer period. These medications are often taken together at the beginning of a cluster period. Patients typically discontinue the short-term medication after a couple of weeks but continue taking the long-term drug.
Short-term medications include:
  • Corticosteroids. Commonly used to relieve inflammation, these drugs may be prescribed to treat cluster headaches that have recently developed. They may also be recommended for patients with brief cluster periods and long remissions. Because of the side effects and risks associated with long-term use, such as osteoporosis and diabetes, these drugs are usually taken for only a few days.
  • Nerve block. An anesthetic may be injected into the fibers surrounding the occipital nerve (a nerve located at the back of the head) to prevent pain messages from traveling to the trigeminal nerve and the pain-sensitive structures in the head.
Long-term medications include:
  • Calcium channel blockers. These antihypertensives increase the flow of oxygen-rich blood to the heart, lower blood pressure and reduce the workload of the heart. They may be used from the development of a cluster period until three to four weeks following the last headache. In some cases the medication may be used for a longer period of time to treat chronic cluster headache.
  • Lithium. A drug that acts on the central nervous system and is commonly used to treat bipolar disorder (manic-depressive illness), lithium is also prescribed to prevent chronic cluster headache.
Additional preventive medications include:
  • Beta blockers. These antihypertensives decrease the workload of the heart and lower blood pressure.
  • Tricyclic antidepressants. These drugs are commonly used to treat depression but also can help relieve some pain conditions. Antidepressants may increase the risk of suicidal thinking and behavior in children and adolescents. As a result, people being treated with these drugs should be closely monitored for unusual changes in behavior, according to the U.S. Food and Drug Administration (FDA).
  • Antihistamines. These drugs are commonly used to treat allergic reactions and prevent an increase in release of histamines. However, these drugs are not usually effective in treating a cluster headache once an attack begins.
  • Indomethacin. This nonsteroidal anti-Inflammatory drug (NSAID) is commonly prescribed to relieve pain, tenderness, inflammation and stiffness.
Medications used to treat cluster headaches have variable effectiveness in different people. In many cases, a number of medications may be tried before an effective drug, or combination of drugs, is found.

Though men are far more likely than women to have cluster headaches, they may be undertreated. A recently completed nine-year British study involving more than 400,000 patients found that women are more likely to seek medical help for headaches and to receive prescriptions. Anyone suffering from cluster headaches or other headaches is advised to take the initiative in seeking help.

In addition to taking medications, patients may reduce the frequency of cluster headaches by avoiding factors that trigger the headaches. Patients may identify these triggers by keeping a headache diary for two months or longer. To compile this journal, patients record certain information after each headache occurs, including:
  • When the headache occurred
  • How severe the headache was
  • Where the headache was located
  • How long the headache lasts
  • Medications taken prior to and after the headache
  • Events before the headache (e.g., consumption of alcohol)
  • Sleep patterns and amount of sleep
In general, there are a number of steps a patient can take to avoid a cluster headache, including:
  • Avoiding alcohol because it often triggers attacks during a cluster period
  • Avoiding cigarettes and other tobacco products
  • Maintaining a regular sleep schedule
  • Avoiding afternoon naps
  • Avoiding certain medications if possible (e.g., nitroglycerin)
  • Avoiding glare and bright lights
In rare instances, surgery may be recommended for treatment of chronic cluster headaches. Patients who do not respond to medication and those who cannot tolerate the side effects of medication may benefit from this form of treatment. However, surgery might be an option only for patients who experience pain on one side of their head. Because the surgery can be performed only once, patients experiencing pain on alternating sides of the head risk that the procedure will be ineffective.
A number of surgeries may be used to treat the trigeminal neuralgia that may be associated with cluster headaches (cluster-tic syndrome):
  • Conventional surgery (trigeminal nerve section). A surgeon uses a scalpel to sever part of the trigeminal nerve (the nerve in the head believed to be responsible for pain), or uses tiny burns to destroy a section of the nerve. Conventional surgery provides relief for the majority of people who undergo the procedure.
  • Radiosurgery. A surgeon uses a focused beam of radiation to destroy a section of the trigeminal nerve. Although this form a surgery is noninvasive and linked with fewer side effects, the safety and permanency of the procedure have not been established.
As with many of the medications used to treat cluster headache, surgical techniques also carry the risk of side effects. The procedures, which are aimed at damaging the trigeminal nerve, may result in residual muscle weakness in the jaw or decreased sensation in areas of the face and head.



Periactin (Cyproheptadine), Topamax (Topiramate), Trileptal (Oxcarbazepine)


  • Avoid any activities that could cause you to injure yourself during attacks.
  • Vigorous physical activity at first symptoms may abort attack.


  • During clusters, avoid alcohol as it can precipitate attack.
  • Rarely, specific foods (chocolate, eggs, dairy products) trigger attacks.

What might complicate it?

Overuse of pain medicines can result in their becoming ineffective. There is a risk of drug addition.

Predicted outcome

The outcome is variable. Headaches may be well managed medically, or they may resist treatment. Headaches may come and go in cycles.


Migraine headache, rebound headache, and temporal arteritis are other possibilities.

Appropriate specialists


Seek Medical Attention

  • You or a family member has symptoms of cluster headache.
  • Attacks continue after treatment is started.

Last updated 4 July 2015