Often confused with migraine, a type of headache disorder that can also cause serious discomfort, cluster headache is a relatively rare condition that occurs in about 1 in 1,000 to 1 in 5,000 people, explains Emmanuelle Schindler, MD, PhD, a Yale Medicine neurologist.
“This disorder is characterized by a particularly severe kind of headache, which can happen multiple times a day,” she says. “In some patients, the attacks occur year-round—called chronic cluster headache; in others, the attacks occur for a period of weeks to months—called episodic cluster headache.”
The disorder gets its name because the headache attacks occur in clusters of time, usually at the same time(s) of day. For those with episodic cluster headache, the periods of attacks also occur at the same time each year.
Unfortunately, many people aren’t properly diagnosed with cluster headache, and even when they are, the treatment options are limited and don’t work for everyone, Dr. Schindler adds, which is why she is motivated to continue her research for better therapies.
Below, we talk more with Dr. Schindler about cluster headache and how it differs from other, more common headache disorders.
What does a cluster headache attack feel like?
A cluster headache attack starts suddenly and creates severe pain on one side of the head, around the eye, lasting between 15 minutes and three hours. It may also include other symptoms such as tearing, reddening of the eye, a drooping eyelid, and a stuffy nose. It can occur daily or almost daily for weeks, months, or years at a time. “Patients describe cluster headache attacks as a searing, ripping pain behind and around their eye,” says Dr. Schindler.
The headache attacks can occur as often as eight times a day, but in most cases, people have attacks about twice a day and frequently at night, with a headache that wakes them up from sleep.
Cluster headache is more common in men than in women, tends to run in families, and can happen at any age (though it most often arises in people in their 20s through middle age).
The cause of cluster headache is unknown, but the hypothalamus, a small area deep in the brain that modulates several neurobiological systems, has been shown to be activated during cluster attacks.
What is the difference between cluster headache, migraine, and tension-type headache?
Migraine is one of the most widely recognized headache disorders. It is found in about 15% of the population and, like cluster headache, runs in families, Dr. Schindler explains. “In contrast to cluster attacks, migraine attacks last several hours and are often accompanied by light and sound sensitivity, nausea, and sometimes vomiting,” she says. “There are numerous treatments for migraine, though not all are effective.”
While migraine might be the most widely known headache disorder, tension-type headache is the most common, and is estimated to affect up to 80% of people at some point in their life, Dr. Schindler adds. “I think we all know what this feels like—a squeezing pain around your head that happens at the end of a long day,” she says. “These headaches usually aren’t a problem unless they become chronic.”
How do I know if I have a cluster headache disorder?
Cluster headache is diagnosed by a doctor, based on the descriptions of the headache attacks and after other conditions have been ruled out. “Unless someone has had cluster headache for many years, these patients should all have brain imaging to make sure there is no abnormality or condition that mimics the symptoms of a headache disorder,” she says.
What are the treatments for cluster headache?
Headache disorders are managed primarily in two ways—acute treatments targeting the individual headache attack and preventive treatments that reduce the overall frequency and severity of the attacks.
For the acute treatment of cluster headache, the gold standard is high-flow oxygen. This involves breathing oxygen in through a non-rebreather mask (a medical device to assist in oxygen delivery) at 10 to 15 liters per minute.
“High-flow oxygen can be effective in about 75% of patients with cluster headache and can be used at home, though there are several barriers to accessing this important treatment,” says Dr. Schindler. “Sometimes, clinicians aren’t aware of the treatment or don’t know how to order it, and then patients are not instructed on where to obtain the oxygen or how to properly use it.”
Insurance coverage for home oxygen is not uniform, and some patients are unable to have the treatment covered, even after providing scientific literature and letters from their doctors to the company, she adds.
Other options for acute treatment include triptan medications—sumatriptan (brand name Imitrex®) and zolmitriptan (brand name Zomig®), which are also used to treat migraine. “For cluster headache, triptans must be administered via nasal spray or injection just under the skin to get into the body very quickly,” says Dr. Schindler. “Oral pills take too long to get into the bloodstream—about as long as the cluster attack will last on its own.”
Anti-inflammatory medications, such as ibuprofen, are not effective in treating cluster headache, particularly when administered orally, she adds. “Narcotics should also not be prescribed for cluster headache or any other headache disorder as they are not effective and serve to generate more attacks,” she says. “Unfortunately, cluster headache patients are sometimes still prescribed narcotics, and they can become addicted to them.”
Preventive treatments for cluster headache include verapamil (brand name Verelan®), a medication also used to lower blood pressure, and galcanezumab (brand name Emgality®). Other treatments that can shorten a cluster cycle or induce a period of remission in chronic cluster headache include steroids, such as prednisone, and injections of dihydroergotamine (DHE), a medication also used to treat migraine.
What new treatments are researchers studying for headache disorders?
Dr. Schindler and colleagues at Yale and the Veterans Affairs (VA) Connecticut Healthcare System in West Haven, CT, are currently studying how psilocybin (a psychedelic found in “magic mushrooms”) can be used to treat cluster headache, migraine, and post-traumatic headache (which can occur after a head injury).
“These studies are very preliminary and aim to determine what effect psilocybin has on cluster headache and if it is safe,” she says. “With migraine, after a single, relatively low dose of psilocybin, patients reported a reduction in the number of migraine attacks by about one-half. We only measured over a two-week period, but that reduction was sustained over those two weeks. So far, there’s no other medication you can take by mouth one time that will give you that much reduction in headache burden.”
With cluster headache, treatment with three doses of psilocybin reduced cluster attack frequency by about 30% over a number of weeks in the trial, she adds. "Another group in Denmark showed a similar effect in their study, which has not yet been peer-reviewed. Other groups in Europe are currently studying the effects of lysergic acid diethylamide [LSD] on cluster headache," she says.
While the use of psychedelics, such as psilocybin for depression, and other compounds, such as methylenedioxyamphetamine (MDMA) for post-traumatic stress disorder, have been widely discussed recently, no psychedelic drugs have been approved for medical use by the U.S. Food and Drug Administration.
What's more, Dr. Schindler cautions that these are powerful substances. “They have to be used responsibly and for the right reason,” she says. “And some people should not take them. So, while there is a lot of excitement around them as a potential treatment, we want to ensure they are safe and effective, which is why we are conducting clinical trials.”
In the meantime, if any headache disorder affects your ability to function on a daily or near-daily basis, or if the headache pain is very severe, you should consider making an appointment with a neurologist or headache specialist, Dr. Schindler advises.