Cluster Headache in 2026: Causes, Diagnosis, and Treatment

Headache Medicine
Anton Ostashko, MD·Last medically reviewed July 10, 2026

Overview

Cluster headache is a primary headache disorder in the trigeminal autonomic cephalalgia family. It causes repeated attacks of excruciating unilateral pain around the eye, temple, or forehead, together with same-side eye redness or tearing, nasal congestion, eyelid swelling, facial sweating, a drooping eyelid or small pupil, and/or marked restlessness.1

Cluster attacks escalate quickly and are too brief for ordinary oral pain medicines to work reliably. Treatment therefore has three parts: a fast acute therapy for each attack, a short bridge while prevention takes effect, and a preventive plan for the active cluster period.2

The most important points in 2026 are:

  • High-flow 100% oxygen and subcutaneous sumatriptan remain first-line acute treatments. The EAN strongly recommends oxygen at a flow of at least 12 L/min for about 15 minutes and sumatriptan 6 mg subcutaneously when medically appropriate.24
  • Verapamil remains the main preventive medication. It requires individualized dosing and ECG monitoring because it can slow cardiac conduction.2
  • Galcanezumab is not a universal cluster-headache drug. Its U.S. indication is for treatment of episodic cluster headache in adults during a cluster period—not chronic cluster headache.3
  • Neuromodulation is promising but device- and phenotype-specific. Evidence varies substantially across noninvasive vagus-nerve stimulation, sphenopalatine-ganglion stimulation, occipital-nerve stimulation, and other approaches.6
  • The condition carries a serious mental-health burden. Suicidal thoughts during severe bouts require immediate support and emergency care.

Evidence cutoff: This article reflects publicly available evidence through July 10, 2026. Oxygen, triptans, steroids, verapamil, lithium, and procedures all have important contraindications and require individualized prescribing.

Recognizing Cluster Headache

ICHD-3 defines attacks lasting 15 to 180 minutes when untreated, occurring from once every other day to as often as eight times per day. The pain is severe or very severe and strictly unilateral in the orbital, supraorbital, and/or temporal region. Attacks may occur at nearly the same time each day, often at night, and alcohol can trigger attacks during an active bout.1

Unlike many people with migraine who prefer to lie still, people with cluster headache often pace, rock, press the head, or feel unable to remain still. Nausea and light or sound sensitivity can occur, so their presence does not automatically mean migraine.

Episodic versus chronic cluster headache

  • Episodic: cluster periods lasting days to months separated by remission periods of at least three months.
  • Chronic: attacks continue for at least one year without remission, or with remissions shorter than three months.

The terms describe remission pattern, not pain severity.

Diagnosis and When Imaging Is Needed

Cluster headache is diagnosed from the attack pattern and neurological examination. MRI is commonly obtained at least once—especially at first presentation, with an atypical pattern, abnormal examination, pituitary symptoms, or treatment resistance—to exclude structural disorders that can mimic a trigeminal autonomic cephalalgia.

Important mimics include paroxysmal hemicrania, SUNCT/SUNA, migraine with autonomic symptoms, trigeminal neuralgia, glaucoma, sinus or orbital disease, carotid dissection, pituitary-region lesions, and other secondary causes. A complete response to indomethacin points toward paroxysmal hemicrania rather than cluster headache.

Emergency red flags

Thunderclap onset, new weakness or numbness, speech or vision loss, fever, neck stiffness, confusion, trauma, a painful fixed pupil, or a major change from the usual pattern requires urgent evaluation.

Acute Treatment: Stop the Attack Fast

100% oxygen

Oxygen is inhaled through a non-rebreather mask at a high flow—at least 12 L/min in the EAN recommendation—for approximately 15 minutes, started as early as possible. Some patients require a higher-flow system under specialist guidance. Nasal cannulas generally do not deliver the concentration or flow used in cluster protocols.24

Oxygen is not addictive and does not cause medication-overuse headache. Fire safety is essential: no smoking, flames, or sparks near the equipment. Coverage and home access can be barriers, so a prescription should specify the mask, flow, and quantity needed for multiple daily attacks.

Triptans

Subcutaneous sumatriptan 6 mg is the best-established fast medication. Intranasal sumatriptan or zolmitriptan may help when injections are not acceptable, but onset is generally slower. Oral triptans are often too slow for cluster attacks.24

Triptans may be inappropriate in selected patients with coronary, cerebrovascular, peripheral vascular, or uncontrolled hypertensive disease. Dosing frequency and cardiovascular safety must be reviewed with the prescriber.

What usually does not work well

Acetaminophen, NSAIDs, oral opioids, and oral combination analgesics act too slowly and can add medication toxicity. Opioids are not recommended as routine cluster treatment.

Bridge Treatment

A bridge suppresses attacks while a preventive medication is being titrated. Options include a short course of corticosteroid or a greater occipital nerve injection with local anesthetic and corticosteroid. Steroid exposure is kept brief because repeated or prolonged courses can cause glucose elevation, mood change, insomnia, infection risk, bone loss, and other harms.2

Bridge treatment is not a substitute for prevention when a bout is expected to continue.

Preventive Treatment

Verapamil

Verapamil is the best-established first choice. It may require doses higher than those commonly used for blood pressure. A baseline ECG and repeat ECGs during dose escalation are important because PR prolongation, heart block, bradycardia, edema, and constipation can occur.2

Lithium and topiramate

Lithium is particularly considered in chronic cluster headache but requires serum levels and monitoring of kidney, thyroid, electrolyte, and drug-interaction issues. Topiramate is another option; cognitive slowing, weight loss, kidney stones, glaucoma risk, metabolic acidosis, and pregnancy-related fetal risk must be discussed.

Galcanezumab

Galcanezumab is FDA-approved for episodic cluster headache in adults. The labeled cluster regimen differs from its migraine-prevention regimen: treatment begins at cluster onset and continues monthly until the end of the cluster period. It has not shown the same established benefit in chronic cluster headache.3

Other strategies

Melatonin, noninvasive vagus-nerve stimulation, and other treatments may be considered in selected cases. Evidence and regulatory status vary; a device cleared for one headache phenotype should not be assumed effective for every cluster patient.6

Refractory Chronic Cluster Headache

For severe chronic disease that remains disabling despite expert medical treatment, specialty centers may consider invasive neuromodulation such as occipital-nerve stimulation or other procedures. These require careful selection because infection, lead migration, hardware failure, repeat surgery, and uncertain long-term benefit are meaningful concerns. Destructive trigeminal procedures can create numbness or neuropathic pain and are generally approached cautiously.65

Daily-Life and Safety Planning

  • Maintain immediate access to acute treatment at home, work, and during travel.
  • Avoid alcohol during an active bout if it reliably triggers attacks.
  • Keep a diary of attack timing, duration, acute treatment, and response.
  • Plan sleep and driving safety when attacks occur predictably at night.
  • Ask the oxygen supplier about travel cylinders, backup equipment, and fire-safety rules.

Cluster headache has historically been called “suicide headache” because of the intensity—not because self-harm is inevitable. Any thoughts of suicide, inability to stay safe, or loss of control require immediate crisis support. In the United States, call or text 988; call 911 for immediate danger.

A Practical Treatment Framework

  1. Confirm the phenotype and exclude a secondary cause.
  2. Prescribe a rapid acute plan. Oxygen and/or a fast triptan should be available before the next attack.
  3. Use bridge treatment when appropriate.
  4. Start prevention early in the bout. Verapamil requires ECG-guided titration.
  5. Reassess subtype and adherence. Episodic and chronic cluster headache have different evidence for some treatments.

Bottom line: cluster headache is one of the most severe pain disorders, but it has highly specific treatments. A successful plan is built before the next attack—not after repeated emergency visits.

At Los Altos Neurology, care focuses on confirming the diagnosis, arranging appropriate imaging, building an oxygen and medication rescue plan, monitoring prevention safely, and referring refractory cases to advanced headache programs.

References

  1. International Headache Society. International Classification of Headache Disorders, 3rd edition. ICHD-3: Cluster headache.
  2. May A, Evers S, Goadsby PJ, et al. Eur J Neurol. 2023;30:2955-2979. European Academy of Neurology guidelines on cluster headache treatment.
  3. U.S. Food and Drug Administration. Revised 2026. EMGALITY prescribing information.
  4. Pearson SM, Burish MJ, Shapiro RE, et al. Headache. 2022;62:738-753. Network meta-analysis of acute cluster-headache therapies.
  5. Review of cluster-headache diagnosis and treatment. 2025. Cluster headache: current and emerging treatment.
  6. Review of neuromodulation evidence in cluster headache. 2026. Neuromodulation for cluster headache: 2026 review.

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