Cluster headaches

Cluster headaches are extremely painful headaches that tend to affect one particular side of the head, and are often felt around the eye. The pain may radiate through to other parts of the head.

Cluster headaches are a very rare phenomenon, affecting about 0.1% of the US population. They can also occur at various times and frequencies in a patient’s life, from daily to weekly, monthly, yearly, or even decennially (once per decade. Cluster headache attacks or episodes can last minutes to hours or, in some cases, days.

Although medical cannabis has been shown to be useful in managing many kinds of headache and migraine, the evidence for its efficacy for cluster headaches specifically is mixed.

Cluster headache causes

There is no known cause for cluster headaches, but abnormalities in the body’s biological clock (hypothalamus), an imbalance in serotonin or improper functioning of serotonin receptors, and the use of some heart disease medications like nitroglycerin are potential culprits. Neurological conditions like multiple sclerosis (MS) have also been linked to lesions in the brainstem, increasing the likelihood of cluster headaches.

The pain of a cluster headache is said to be comparable to or even worse than severe burns, the bite of a bullet ant, kidney stones, or giving birth.

Cluster headache symptoms & health effects

Cluster headaches can occur everyday (usually at night), with attacks lasting anything between 15 minutes and 3 hours.

Other symptoms of cluster headaches include:

A sharp, burning, grabbing, or piercing pain, usually on 1 side of the head, around the eye
Red and/or watering eyes
Nasal congestion
Profuse sweating on the forehead
Drooping or swelling eyelid/s
Reduced pupil size
Headaches that happen at the same time of year or at set times of the day
Headaches that start and stop quickly, without warning
Stress, anxiety, and agitation
A need to walk around or move your body due to restlessness

Although headaches and migraines can be longer lasting, they rarely have the intensity of pain cluster headaches do.

Unlike migraines or tension headaches, cluster headaches don’t always have triggers like food, stress, or changes in hormone levels, but sometimes they do. Light, some types of sound, alcohol, tobacco smoking, and strong scents (e.g. perfumes) may trigger episodes in some.

Cluster headache diagnosis

Cluster headaches are in a group of primary headaches called trigeminal autonomic cephalalgia (TAC). TACs include:

Cluster headache
Long-lasting autonomic symptoms with hemicrania (LASH)
Paroxysmal hemicrania (chronic or episodic)
Short-lasting unilateral neuralgiform headache attacks with conjunctival injection and tearing (SUNCT)
Short-lasting unilateral neuralgiform headache attacks with cranial autonomic symptoms (SUNA)

TACs can be differentiated by the length and frequency of recurrence of the headaches. Diagnosis is also made to differentiate between cluster headache and headache caused by other health problems, e.g. a tumor.

A primary care physician is likely to refer to a specialist doctor (neurologist) to make a diagnosis for cluster headaches and to determine the type of TAC. A diagnosis is made based on medical history, symptoms, and a physical and neurological examination.

Cluster headache prognosis

Cluster headaches are not necessarily fatal in and of themselves, but can have a dramatic effect on a patient’s quality of life (QoL). Sadly, due to the excruciating nature of cluster headaches, it can result in an increased chance of suicide.

Cluster headaches are often compared to trigeminal neuralgia due to the type of pain, the areas they affect, the health outcomes, and the medications used to treat them.i. However, the two have distinct clinical features, even if they may be treated by similar methods.

Cluster headache treatments

The precise treatment and drug regimen can depend on the type of cluster headache the patient is trying to manage. However, there are some similarities in the medications prescribed, regardless of the type of cluster headache.

Following a healthy diet, exercise, and regulated sleep patterns can also help prevent stress, anxiety, and infection, which can trigger headaches/migraines of all types.

First-line treatments

The most common medications prescribed for cluster headaches are:

Triptans like Sumatriptan (Imitrex) and zolmitriptan (Zomig) as a nasal spray or injection
Calcium channel blockers like verapamil (Isoptin, Calan)
Mood stabilizers like lithium (Priadol, Lithobid) may be prescribed as a preventative and anti-anxiety medication for cluster headaches
Anti-convulsants like gabapentin (Neurontin, Gralise, Horizant) may be prescribed for chronic and nerve pain associated with cluster headaches
Valproate semisodium (semisodium valproate, divalproex sodium, Depakote), which helps regulate dopamine levels. This medication, or the related alproate (valproic acid, VPA, sodium valproate), are used to manage seizures, bipolar disorder, and other types of migraine.
High-flow oxygen inhalation

Other treatments

Topiramate (Topamax), a medication usually used to treat seizures associated with epilepsy, is the most common second-line medication for cluster headaches.

Rarely, opioids may be prescribed for pain.

medical cannabis

Adjunctive therapy & alternative treatments

Melatonin, a neurotransmitter, can be purchased in tablet form over-the-counter (OTC), and is often used to manage pain and insomnia associated with cluster headaches. However, some people may find that melatonin triggers headaches.

Yoga is also recommended as an adjunctive therapy for various types of headache and migraine.

Due to its effect on serotonin, psilocybin (and psilocin, the “trip” compound found in magic mushrooms) may be a particularly promising treatment for headache disorders like cluster headaches.

Cannabis for cluster headache

Cannabis and cannabinoids have shown some efficacy in treating some suffering from cluster headaches, but an almost equal number found cannabis to be a trigger. Cannabinoids may be useful in reducing intracranial pressure in some cluster headaches sufferers, and may also play a part in preventing the release of serotonin during a headache or migraine. Medical cannabis may be helpful in managing anxiety, insomnia, stress, and stiffness associated with cluster headaches.

Some types of prescription medication may also cause headaches, anxiety, and insomnia when used over the long term, so careful use of medical cannabis can be an alternative to such medications, with fewer side effects.

Still, cannabis may be a trigger for some cluster headache sufferers. This could be via smoking cannabis, where the smoke itself may trigger a headache. For other sufferers, overuse of THC may cause anxiety, which can worsen or trigger cluster headaches. Then, some may find that cannabis only has neutral effects.

The possibility of rebound headache in those who cease to use medical cannabis can also be a concern.

Additional information for patients

There are several charities in the US that provide advocacy, resources, and support services for those with headaches and migraines of various types. These include:

American Headache Society
American Migraine Foundation
Clusterbusters
Headache Advocacy Network aka Coalition for Headache and Migraine Patients (CHAMP)
National Headache Foundation

Cluster headache FAQs

What can trigger cluster headaches?

The triggers for cluster headaches are similar to other types of headaches and migraine. They include:

Alcohol use
Smoking
Stress and anxiety
Depression
Change to a high or extremely low altitude
Bright light
Unpleasant and strong smells
Loud sounds
Exercise or exertion
Heat, from either the weather or a bath
Foods that contain nitrates, such as bacon or lunch meat
Recreational drug use
The side effects of some types of medication
Allergic reactions

What is the difference between a cluster headache and a migraine?

Although there are many similarities between cluster headaches and migraines and their treatment, there are some key differences.

Cluster headaches are generally more painful, include headaches as a symptom, and are shorter-lived (15 minutes to three hours). Meanwhile, migraines do not always include headaches, can last up to 72 hours, and their pain intensity is generally lower.

Both conditions, however, may be related to neurological conditions like multiple sclerosis (MS). Both conditions may also be managed by modulating serotonin.

Does paracetamol help with cluster headaches?

Although paracetamol may be used to manage some minor or moderate headache pain, it is not considered powerful or quick enough to take effect for cluster headaches. More specialist treatments are required.