Cluster headache is the most common trigeminal autonomic cephalalgia (TAC), characterized by recurrent, strictly unilateral, excruciating periorbital/temporal pain lasting 15–180 minutes with ipsilateral cranial autonomic features and restlessness. [1-2] It affects ~0.1% of the population, with a 3:1 male-to-female ratio and mean onset age of 30 years. [3-4] It is considered one of the most painful human experiences and is associated with high rates of suicidal ideation. [1-2]
The following algorithm from the AAFP provides a practical approach to evaluating acute headache and distinguishing cluster headache from other diagnoses:
1. History
- Location: Strictly unilateral — orbital, supraorbital, or temporal region; always same side within a bout [1]
- Quality: Excruciating, boring, stabbing; often described as "hot poker behind the eye"
- Duration: 15–180 minutes untreated [1]
- Frequency: Every other day up to 8 attacks/day [3]
- Timing: Strong circadian pattern — peak between 21:00–03:00; up to 80% describe sleep as a trigger [1][5]
- Circannual pattern: Bouts cluster in spring and autumn [5]
- Behavior during attack: Restlessness and agitation (pacing, rocking) — in contrast to migraine patients who lie still [1][3]
- Autonomic symptoms: Ipsilateral lacrimation, conjunctival injection, nasal congestion/rhinorrhea, ptosis, miosis, eyelid edema, facial sweating [3]
- Bout pattern: Episodic (bouts 7 days–1 year with ≥3-month remission) vs. chronic (no remission or <3 months) [1]
- Ask about precluster symptoms — 35–57% of patients can predict an impending bout [1]
2. Alarm Features
- New-onset headache in older adults, systemic fever, or vision loss [1]
- Focal neurological signs beyond expected autonomic symptoms [1]
- Persistent autonomic symptoms between attacks [1]
- Sudden change in headache character (onset, frequency, severity, location) [3]
- "Worst headache of life" or thunderclap onset → rule out subarachnoid hemorrhage [3]
- Change in mental status or personality [3]
- Suicidal ideation — actively screen; 47% lifetime active suicidal ideation in one study, OR 3.9 for suicide attempt vs. general population [1][6]
3. Medications
Abortive (First-Line)
- 100% oxygen via non-rebreather mask at 12–15 L/min for 15–20 min, seated position — effective in ~2/3 of patients; no side effects, repeatable [1][7]
- Sumatriptan 6 mg SC — pain relief in ~74% within 15 min; fastest onset [1][3]
- Sumatriptan 20 mg intranasal or zolmitriptan 5–10 mg intranasal — second-line, onset ~30 min [1][7]
- Intranasal lidocaine (4–10%) to ipsilateral nostril — third-line, effective in ~1/3 [3][7]
Transitional (Bridge)
- Prednisone taper (~60–80 mg/day for ~2 weeks) [4][7]
- Greater occipital nerve (GON) block with lidocaine + steroid (e.g., dexamethasone) ipsilateral to pain [1][4]
Preventive
- Verapamil 240–960 mg/day (first-line) — requires ECG before initiation and after each dose increase; ECG abnormalities can appear even after years on stable dose [7-8]
- Lithium 600–900 mg/day (target level 0.6–0.8 mmol/L) — monitor renal/thyroid function [7][9]
- Galcanezumab 300 mg SC monthly — FDA-approved for episodic cluster headache [4][10]
- Second-line: topiramate 100–200 mg/day, melatonin 10 mg [11-12]
Contraindicated/Cautions
- Triptans contraindicated in cardiovascular disease, cerebrovascular disease, uncontrolled hypertension [3]
- Oral triptans generally too slow for cluster attacks [1][7]
- Opioids — avoid; ineffective and risk of dependence [13]
- Indomethacin does NOT work for cluster headache (distinguishes from paroxysmal hemicrania) [1]
4. Diet
- Alcohol is the most reliable dietary trigger — even small amounts can provoke attacks during a bout; typically does not trigger during remission [7][14]
- Foods containing nitrates (cured meats, hot dogs) may trigger attacks [3]
- Strong odors (solvents, perfumes, cigarette smoke) are triggers [3][14]
- No specific dietary management beyond trigger avoidance
- Adequate hydration is generally recommended
5. Review of Systems
- Neuro: Aura, photophobia, phonophobia (can occur in cluster headache but less prominent than migraine), focal deficits
- Psych: Depression, anxiety, suicidal ideation — screen actively [1][6]
- Sleep: Insomnia, sleep disruption, nocturnal awakenings — quality of sleep is lower even during remission [1]
- ENT: Nasal congestion, rhinorrhea, facial pain (distinguish from sinusitis)
- Ophthalmologic: Tearing, redness, ptosis, vision changes
- Cardiovascular: Relevant before prescribing triptans/verapamil [1]
6. Collateral History and Family History
- Family history: First-degree relative with cluster headache increases risk 5–18×; second-degree relative increases risk 1–3× [3]
- Familial in ~10% of cases [14]
- SNP-based heritability estimated at 14.5% [15]
- Genetic correlation with smoking, risk-taking behavior, ADHD, depression, and musculoskeletal pain [15]
- Collateral from bed partner regarding nocturnal restlessness, pacing, and attack timing is valuable
- Substance use history — higher rates of illicit substance use in cluster headache populations [1]
7. Risk Factors
- Male sex (3:1 ratio, though gap is narrowing) [3][7]
- Smoking: 60–88% of patients have a smoking history; Mendelian randomization suggests causal effect of smoking on cluster headache [1][15]
- Age 20–40 at onset [3]
- Seasonal changes — bouts peak in spring and autumn [5]
- Genetic susceptibility (CLOCK gene, REV-ERBα associations) [5]
- Head trauma (historical association, less well-established)
8. Differential Diagnosis
- Migraine: Longer duration (>3 hours), patients lie still, more nausea/photophobia/phonophobia; movement worsens pain [1][3]
- Paroxysmal hemicrania: Shorter attacks (2–30 min), more frequent (>5/day), responds to indomethacin (absolute response is diagnostic) [1]
- SUNCT/SUNA: Very short attacks (seconds to minutes), very high frequency [1]
- Hemicrania continua: Continuous unilateral pain with exacerbations; responds to indomethacin [1]
- Trigeminal neuralgia: Seconds-long lancinating pain, triggered by external stimuli (chewing, cold wind); autonomic features uncommon [1]
- Secondary causes (cannot-miss): Pituitary adenoma, carotid dissection, intracranial aneurysm, posterior fossa lesion, orbital pathology [1][3]
9. Past Medical History
- Prior headache history and previous diagnoses (average diagnostic delay is years) [7]
- Previous bouts — frequency, duration, seasonality, treatments tried
- Cardiovascular disease (impacts triptan/verapamil use) [1]
- Psychiatric history — depression, anxiety, prior suicide attempts [1]
- Medication history including prior prophylactic trials and responses
- History of head/facial trauma
10. Physical Exam
Vital Signs: Generally normal between attacks; tachycardia/hypertension possible during attack due to pain/agitation
During Attack
- Patient is restless, pacing, rocking — pathognomonic behavioral feature [1][3]
- Ipsilateral conjunctival injection, lacrimation
- Ipsilateral ptosis, miosis (partial Horner syndrome)
- Ipsilateral nasal congestion/rhinorrhea
- Ipsilateral eyelid edema, facial flushing/sweating
Between Attacks
- Neurological exam should be normal — any focal deficit or persistent autonomic signs suggest secondary cause [1]
- Fundoscopic exam — rule out papilledema
- Palpate temporal arteries (giant cell arteritis in older patients)
11. Lab Studies
- No routine labs are diagnostic for cluster headache
- If secondary cause suspected: ESR/CRP (temporal arteritis), CBC, BMP
- Before verapamil: Baseline ECG [1][7]
- Before lithium: BMP (renal function), TSH, lithium level monitoring (target 0.6–0.8 mmol/L) [7][9]
- Pituitary labs if imaging suggests sellar pathology
12. Imaging
- Not routinely recommended for typical presentations meeting ICHD-3 criteria [3]
- Indications for neuroimaging (CT or MRI): [1][3]
- New-onset headache with atypical features
- Sudden change in headache character
- Focal neurological findings
- Persistent autonomic symptoms between attacks
- Systemic illness (fever, weight loss)
- MRI brain with contrast is preferred over CT when imaging is indicated — to evaluate for pituitary adenoma, cavernous sinus pathology, posterior fossa lesions [1]
- CTA if vascular pathology (dissection, aneurysm) is suspected [1]
13. Special Tests
- Indomethacin trial: If diagnostic uncertainty between cluster headache and paroxysmal hemicrania/hemicrania continua — a complete response to indomethacin rules out cluster headache [1]
- Greater occipital nerve block: Both diagnostic and therapeutic [1]
- Non-invasive vagus nerve stimulation (nVNS): Adjunctive acute and preventive treatment, effective in episodic but not chronic cluster headache [1][4]
- Sphenopalatine ganglion stimulation: Implanted device for refractory chronic cluster headache [4]
14. ECG
- Mandatory before starting verapamil and after each dose increase [1][7]
- Monitor for PR prolongation, bradycardia, AV block [8]
- ECG abnormalities can appear after months to years on stable verapamil dose — ongoing periodic monitoring recommended [7-8]
- At doses ≥480 mg/day, consider Holter monitoring [16]
- Incidence of ECG changes ~38% at very high doses (≥720 mg/day); 14% had serious arrhythmias (heart block) [8]
- Also obtain baseline ECG before triptans in patients with cardiovascular risk factors [1]
15. Assessment
Cluster headache is a clinical diagnosis based on ICHD-3 criteria. [1] Key diagnostic features:
- ≥5 attacks of severe unilateral orbital/supraorbital/temporal pain lasting 15–180 min
- Accompanied by ≥1 ipsilateral autonomic symptom OR restlessness/agitation
- Attacks occur every other day to 8/day
Severity stratification
- Episodic (~90%): Bouts lasting 7 days–1 year with ≥3-month remission [1]
- Chronic (~10%): No remission or remission <3 months; more treatment-resistant [4][17]
Typical diagnostic delay is years, often misdiagnosed as migraine, sinusitis, or dental pain. [2][7] Atypical features (nausea, photophobia) can occur in cluster headache and contribute to misdiagnosis. [7]
16. Treatment Plan
In the ED — Acute Attack
- 100% O₂ at 12–15 L/min via non-rebreather, patient seated, for 15–20 min [1][7]
- Sumatriptan 6 mg SC if oxygen insufficient or unavailable [1][3]
- Intranasal lidocaine (4–10%) to ipsilateral nostril if triptans contraindicated [3][7]
Transitional (Bridge) Therapy
- Prednisone 60–80 mg/day tapered over ~2 weeks OR
- GON block with lidocaine + dexamethasone ipsilateral to pain [4][7]
Preventive Therapy (initiate concurrently with bridge)
- Verapamil starting 80 mg TID, titrate to 240–480 mg/day (up to 960 mg in refractory cases); ECG monitoring required [4][7]
- Galcanezumab 300 mg SC monthly for episodic cluster headache [4][10]
- Lithium 600–900 mg/day for chronic cluster headache [4][7]
Non-pharmacologic
- Strict alcohol avoidance during bouts [7][14]
- Smoking cessation counseling [1][15]
- Sleep hygiene optimization [1]
- Screen and treat depression/suicidality [1][6]
17. Disposition
Discharge criteria
- Attack aborted with oxygen or sumatriptan
- Established diagnosis with outpatient follow-up arranged
- Prescriptions for home oxygen and SC sumatriptan provided
- Bridge therapy initiated (prednisone taper or GON block performed)
- No red flag features
Admission/observation considerations
- Refractory status cluster (multiple prolonged attacks unresponsive to treatment)
- Active suicidal ideation [1][6]
- Need for IV dihydroergotamine protocol in refractory cases
- New diagnosis with atypical features requiring workup
Specialist consultation triggers
- New diagnosis → neurology/headache specialist referral [13]
- Chronic cluster headache or treatment failure → headache center
- Cardiovascular concerns with verapamil → cardiology
- Active psychiatric comorbidity → psychiatry
18. Follow Up / Return Precautions
Follow-up timing
- Neurology/headache specialist within 1–2 weeks for new diagnoses
- ECG within 1–2 weeks of starting or uptitrating verapamil [7]
- Lithium level check 5–7 days after initiation; renal/thyroid monitoring every 6 months [7][9]
Return precautions — seek immediate care for
- Attacks not responding to prescribed abortive therapy
- New neurological symptoms (weakness, vision loss, speech changes)
- Suicidal thoughts or self-harm urges
- Chest pain, palpitations, or syncope (especially on verapamil)
- Fever, neck stiffness, or altered mental status
Patient counseling
- Cluster headache is a treatable condition; attacks can be aborted and bouts shortened with proper therapy
- Avoid alcohol completely during bouts [7]
- Keep oxygen and sumatriptan readily accessible at home and work
- Attacks are self-limited (15–180 min) even without treatment
- Expected course is unpredictable — some patients have single lifetime bouts, others progress to chronic form [14]
References
1. Recent Advances in Diagnosing, Managing, and Understanding the Pathophysiology of Cluster Headache. — Petersen AS, Lund N, Goadsby PJ, et al. The Lancet. Neurology. 2024.
2. Recent Advances in the Diagnosis and Management of Cluster Headache. — Schindler EAD, Burish MJ. BMJ. 2022.
3. Cluster Headache: Rapid Evidence Review. — Malu OO, Bailey J, Hawks MK. American Family Physician. 2022.
4. Diagnosis and Management of Headache: A Review. — Robbins MS. The Journal of the American Medical Association. 2021.
5. Circadian Features of Cluster Headache and Migraine: A Systematic Review, Meta-Analysis, and Genetic Analysis. — Benkli B, Kim SY, Koike N, et al. Neurology. 2023.
6. Demoralization Predicts Suicidality in Patients With Cluster Headache. — Koo BB, Bayoumi A, Albanna A, et al. The Journal of Headache and Pain. 2021.
7. Diagnosis, Pathophysiology, and Management of Cluster Headache. — Hoffmann J, May A. The Lancet. Neurology. 2018.
8. Cardiac Safety in Cluster Headache Patients Using the Very High Dose of Verapamil (≥720 Mg/Day). — Lanteri-Minet M, Silhol F, Piano V, Donnet A. The Journal of Headache and Pain. 2011.
9. Pharmacotherapy for Cluster Headache. — Brandt RB, Doesborg PGG, Haan J, Ferrari MD, Fronczek R. CNS Drugs. 2020.
10. FDA Orange Book. — FDA Orange Book. 2026.
11. Drug Treatment of Cluster Headache. — Diener HC, May A. Drugs. 2022.
12. Acute and Preventive Pharmacologic Treatment of Cluster Headache. — Francis GJ, Becker WJ, Pringsheim TM. Neurology. 2010.
13. Acute Headache Management in Emergency Department. A Narrative Review. — Giamberardino MA, Affaitati G, Costantini R, Guglielmetti M, Martelletti P. Internal and Emergency Medicine. 2020.
14. Cluster Headache. — Leroux E, Ducros A. Orphanet Journal of Rare Diseases. 2008.
15. Cluster Headache Genomewide Association Study and Meta-Analysis Identifies Eight Loci and Implicates Smoking as Causal Risk Factor. — Winsvold BS, Harder AVE, Ran C, et al. Annals of Neurology. 2023.
16. Cardiac Monitoring of High-Dose Verapamil in Cluster Headache: An International Delphi Study. — Koppen H, Stolwijk J, Wilms EB, et al. Cephalalgia : An International Journal of Headache. 2016.
17. Long-Term Safety, Tolerability, and Efficacy of Eptinezumab in Chronic Cluster Headache (CHRONICLE): An Open-Label Safety Trial. — Tassorelli C, Jensen RH, Goadsby PJ, et al. The Lancet. Neurology. 2025.