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This is a clinician-written, evidence-based summary aligned to the 2026 MLA Content Map. It is intended for medical students and junior doctors preparing for the UKMLA. Always cross-reference with NICE guidance, local protocols, and clinical judgement.
The Bottom Line
- Excruciating unilateral periorbital pain (often described as the worst pain imaginable) with ipsilateral autonomic features
- Attacks last 15–180 minutes, occur 1–8 times daily, often at the same time (especially nocturnal, waking from sleep)
- Acute treatment: high-flow oxygen 15 L/min via non-rebreather mask OR subcutaneous sumatriptan 6 mg
- Prophylaxis during cluster period: verapamil (first-line, with ECG monitoring) — specialist initiation
- More common in men (3:1), unlike migraine. Patient is typically restless and agitated (not lying still)
Overview
Cluster headache is the most common trigeminal autonomic cephalalgia (TAC). It causes severe unilateral periorbital or temporal pain with ipsilateral cranial autonomic features. Attacks occur in clusters lasting weeks to months (episodic cluster headache, ~80–90%), separated by remission periods of months to years. Chronic cluster headache (~10–20%) has no remission periods >3 months. The pathophysiology involves hypothalamic activation (circadian pattern) and trigeminovascular system engagement.
Epidemiology
Cluster headache affects approximately 0.1% of the population. It is 3–4 times more common in men (one of few headache types more common in males). Mean age of onset is 20–40 years. Smoking and alcohol are common triggers during cluster periods. There is an association with sleep apnoea.
Clinical Features
Symptoms
Severe unilateral periorbital or temporal pain — described as boring, stabbing, "like a hot poker in the eye"
Pain peaks rapidly (within minutes) and lasts 15–180 minutes
Attacks occur 1–8 times daily, often at the same time each day (circadian pattern, commonly nocturnal)
Restlessness and agitation during attacks (patients pace, rock, cannot lie still — contrasts with migraine)
Cluster period: attacks occur daily for 4–12 weeks, then remit for months-years
Signs
Ipsilateral lacrimation (tearing)
Ipsilateral conjunctival injection (red eye)
Ipsilateral nasal congestion or rhinorrhoea
Ipsilateral ptosis and/or miosis (partial Horner syndrome)
Ipsilateral forehead/facial sweating
Ipsilateral eyelid oedema
Investigations
First-line
Clinical diagnosisBased on ICHD-3 criteria: severe unilateral orbital/supraorbital/temporal pain + ipsilateral autonomic features + restlessness + attack duration 15–180 min
Second-line
MRI brain with pituitary viewsRecommended by NICE CG150 to exclude structural lesion (particularly pituitary tumour or posterior fossa lesion) in ALL new presentations of cluster headache
Specialist
ECGRequired before starting verapamil (risk of heart block) and after dose titration
1
Acute treatment
- High-flow 100% oxygen: 15 L/min via non-rebreather mask for 15–20 minutes. First-line. Effective in ~70%
- Subcutaneous sumatriptan 6 mg — rapid onset, effective in ~75%. Can also use nasal sumatriptan or zolmitriptan
- Oral triptans are too slow for cluster headache (attacks peak rapidly)
- Do NOT use paracetamol, NSAIDs, or opioids — they are ineffective for cluster headache
2
Prophylaxis during cluster period
- Verapamil (first-line): starting dose 240 mg/day, titrated up to 960 mg/day. ECG before and after EACH dose increase (risk of heart block)
- Short course of prednisolone may be used as bridging therapy while verapamil takes effect
- Lithium: second-line prophylaxis, especially for chronic cluster headache. Monitor lithium levels, renal and thyroid function
- Greater occipital nerve block (local anaesthetic ± steroid): may provide temporary relief
Complications
- Chronic cluster headache: ~10–20% have no remission periods >3 months — very disabling
- Depression and suicidal ideation: The severity of pain carries significant psychological burden — sometimes called "suicide headache". Screen and support actively
- Verapamil side effects: Heart block (requires ECG monitoring), constipation, peripheral oedema
- Impact on quality of life: Sleep disruption, inability to work during cluster periods
UKMLA Exam Tips
- 1Severe unilateral periorbital pain + lacrimation + nasal congestion + ptosis + restlessness = cluster headache
- 2Patient is RESTLESS and AGITATED (pacing, rocking) — NOT lying still in a dark room (that is migraine)
- 3Acute: high-flow oxygen 15 L/min OR subcutaneous sumatriptan 6 mg. NOT oral triptans (too slow)
- 4Prophylaxis: verapamil (first-line) with ECG monitoring before and after dose increases
- 5MRI brain recommended for ALL new presentations of cluster headache (NICE CG150)
- 6Male predominance (3:1) — unlike migraine which is female-predominant
- 7Attacks often nocturnal and at the same time each day — hypothalamic circadian involvement
practicetest your knowledge on cluster headacheApply what you've learnt with UKMLA-style questions from the iatroX Q-Bank — neurology and beyond.
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