How is cluster headache different from migraine?

The key difference is behaviour during an attack: migraine patients lie still and avoid movement; cluster headache patients pace, rock, or bang their head — the pain is that severe. Cluster attacks also last only 15–180 minutes (migraine lasts 4–72 hours), occur strictly on one side almost always, cause prominent eye watering, redness, nasal congestion, and drooping of the eyelid on the pain side. Cluster headache is also strongly circadian — attacks tend to strike at the same time each day, often waking people from sleep at 1–3 am during a cluster bout.

Why is oxygen the first treatment for cluster headache attacks?

High-flow oxygen — 100% via a non-rebreather mask at 12–15 L/min for 15 minutes, sitting upright — aborts around 70% of attacks within 15 minutes, with no dependence risk, no medication-overuse risk, and no contraindication in pregnancy or cardiac disease. The oxygen must be high-flow through a non-rebreather mask; low-flow oxygen through nasal cannulae is not effective and a failed trial at low flow does not rule out the diagnosis. Subcutaneous sumatriptan is the complementary acute treatment when oxygen gives partial relief.

How is verapamil used to prevent cluster headache?

Verapamil is the first-line preventive for cluster headache. It is started at 80 mg three times daily (240 mg total daily) and increased by 80 mg every 10–14 days until attacks suppress or side effects limit the dose. The usual effective dose is 240–480 mg per day. An ECG must be performed before starting and before every dose increase, because verapamil can prolong the PR interval, cause AV block, or slow the heart rate in around 20% of patients. These side effects can appear at any dose, sometimes with a delay — making the ECG monitoring non-negotiable.

What is a cluster bout, and how long does it last?

A cluster bout (or cluster period) is the active phase when attacks occur daily, often at fixed times, for weeks to months. Most people have episodic cluster headache — bouts last 7 days to one year, then give way to remission periods of at least three months. About 15% have chronic cluster headache, where bouts persist for more than one year without a sustained remission. Between bouts, people feel completely well. Bouts tend to return in the same season each year, often spring or autumn. Alcohol reliably triggers attacks during an active bout but not during remission — a useful diagnostic clue.

How do I get home oxygen for cluster headache in Australia?

Domiciliary oxygen for cluster headache is available through state-based respiratory subsidy programs — EnableNSW in New South Wales, Domiciliary Oxygen Therapy Service in Victoria, Queensland's Oxygen Subsidy Scheme, and similar programs in other states. Your GP writes a script confirming the diagnosis, attack frequency, and oxygen flow rate required. Where a state program doesn't cover cluster headache specifically, medical-grade oxygen cylinders can be hired from companies such as AirLiquide, BOC, and Coregas on a GP prescription. Both a cylinder and a non-rebreather mask are needed — the mask is as important as the oxygen itself.

Cluster headache

Cluster headache: acute care and prevention — the AU GP approach

By Dr HB Lo, FACRRM Reviewed 5 July 2026 9 min read

Cluster headache is a trigeminal autonomic cephalalgia: one-sided, severe periorbital pain lasting 15–180 minutes, up to 8 attacks per day, with ipsilateral eye watering, nasal congestion, ptosis, and restless pacing — the opposite of migraine.

Attacks are aborted with 100% oxygen via non-rebreather mask at 12–15 L/min for 15 minutes and subcutaneous sumatriptan 6 mg. The cluster bout is prevented with verapamil, titrated with ECG monitoring before every dose increase.

All new diagnoses require MRI brain with contrast to exclude a structural mimic. Suicidal ideation occurs in up to half of untreated patients — screen at every visit.

What cluster headache actually is

Cluster headache belongs to a family of conditions called trigeminal autonomic cephalalgias — headaches driven by activation of both the trigeminal nerve and the autonomic nervous system on the same side of the face. The pain is strictly one-sided, centred behind or around one eye or temple, severe to excruciating in intensity, and lasts between 15 and 180 minutes per attack. During an attack, the affected side produces autonomic features: the eye waters and reddens, the eyelid droops (ptosis), the pupil may constrict (miosis), and the nostril congests then runs. The defining behavioural feature is restlessness and agitation — the person paces, rocks, and cannot keep still, which is the opposite of migraine, where patients prefer to lie completely still.

Attacks group into cluster bouts lasting weeks to months, during which they recur at strikingly predictable times — often once to eight times per day, frequently waking the person from sleep at 1–3 am. Between bouts, most people are completely well. About 0.1% of Australians live with cluster headache — roughly 25,000 people nationally — and the average time to diagnosis from symptom onset is five to seven years, according to Headache Australia. Men and women are now affected at a ratio of about 2:1, a narrowing from the historical 5:1 figure.

A. Core clinical — the AU general practice framework

Recognising cluster headache by its features

The International Classification of Headache Disorders 3rd edition (ICHD-3) diagnostic criteria require at least five attacks of severe, unilateral orbital or temporal pain lasting 15–180 minutes, accompanied by at least one ipsilateral autonomic feature or a sense of restlessness, with attacks occurring from once every two days up to eight per day during an active bout. Therapeutic Guidelines Neurology and Australian Prescriber (2022) both emphasise that the clinical diagnosis rests on this pattern — no blood test confirms it.

Key discriminating features to ask about in the history:

Time of day — attacks at precisely the same hour, often nocturnal (1–3 am is classic)
Season — spring and autumn are most common for cluster bouts
Alcohol during a bout — reliably triggers an attack during an active cluster period but not during remission — a specific and useful diagnostic pointer
Duration — 15–180 minutes (shorter than migraine; longer than paroxysmal hemicrania or SUNCT)
Laterality — strictly the same side in about 95% of attacks

Examination and investigations

During an attack, the examination shows the autonomic features: ipsilateral lacrimation, conjunctival injection, nasal stuffiness or rhinorrhoea, ptosis, miosis, and sometimes facial sweating. Between attacks, the examination is usually normal. A full neurological examination is mandatory, including fundoscopy for papilloedema.

MRI brain with contrast is recommended for every new diagnosis of cluster headache by both Australian Prescriber (2022) and the European Academy of Neurology (EAN 2023). Around 5–10% of patients presenting with cluster-like features have a structural lesion — pituitary adenoma, posterior fossa abnormality, carotid dissection, or arteriovenous malformation. A pituitary protocol should be added if there are endocrine features (galactorrhoea, visual field change, amenorrhoea).

ECG is mandatory before starting verapamil and before every dose increase — not just at baseline. This is addressed in detail in section C below.

Mental health screen at diagnosis — suicidal ideation is reported in 14–55% of cluster headache patients during an untreated active bout, a figure that gives the condition its informal name “suicide headache.” A direct question about thoughts of self-harm is essential at diagnosis and at every subsequent visit.

Red flags in the cluster headache presentation

Any of the following warrant urgent investigation to exclude a secondary mimic before treating as primary cluster headache:

First or worst headache of life — thunderclap onset → rule out subarachnoid haemorrhage (SAH) urgently
Side shift (attacks switching sides) beyond what the patient’s established pattern shows
New neurological deficit, papilloedema, or fever with neck stiffness
Onset after age 50 in a patient with no prior headache history
Change in a previously stable established cluster pattern

B. Acute attack treatment — oxygen and sumatriptan

High-flow oxygen — first-line

The landmark Cohen JAMA 2009 RCT established that 100% oxygen delivered at 12–15 L/min via a non-rebreather mask for 15 minutes, with the patient sitting upright and leaning forward, aborts around 70% of attacks within the treatment window. This is the standard of care per eTG and AMH.

The critical technical point: it must be 100% oxygen through a tight-fitting non-rebreather mask. Nasal cannulae at low flow are not effective, and a failed trial at 2–4 L/min through nasal prongs does not constitute a failed oxygen trial. Oxygen has no dependence risk, no medication-overuse risk, and is safe in pregnancy and cardiac disease.

Oxygen access in Australia varies by state and is detailed in section D below.

Subcutaneous sumatriptan — fastest pharmacological option

Subcutaneous sumatriptan 6 mg via autoinjector produces significant relief within 5–15 minutes in approximately 75% of attacks, per eTG and AMH. The PBS lists sumatriptan injection under Authority Required for cluster headache — a one-off authority script per cluster bout. The maximum dose is two injections per day.

Sumatriptan nasal spray 20 mg is an alternative. Intranasal zolmitriptan 5 mg is effective in international trials but is not currently marketed in Australia, as noted by Australian Prescriber (2022). Oral triptans are too slow for cluster headache attacks and should not be used as the primary acute treatment.

Transitional (bridge) therapy

When a new bout starts and verapamil is being titrated, a short course of prednisolone 60–100 mg/day for 5 days, then tapered over 2–3 weeks, suppresses attacks in about 70% of cases as a bridge. Rebound on taper is common. A greater occipital nerve block (methylprednisolone plus local anaesthetic on the ipsilateral side) can break a cluster bout for two to four weeks and is performed by neurologists or pain medicine specialists.

C. Preventing the cluster bout — verapamil and alternatives

Verapamil: the first-line preventive

eTG, AMH, and the EAN 2023 guideline all position verapamil as first-line preventive treatment for cluster headache. The starting dose is 80 mg three times daily (240 mg total daily), increased by 80 mg every 10–14 days. The target dose range is 240–480 mg per day, with some patients with chronic cluster headache requiring up to 960 mg per day under specialist supervision.

ECG monitoring before each dose increase is non-negotiable. Verapamil causes PR interval prolongation, first- or second-degree AV block, or bradycardia in approximately 20% of patients, and these effects can appear at any dose — sometimes after previously normal ECGs. Australian Prescriber and eTG both specify this monitoring requirement. If the PR interval exceeds 240 ms, or second-degree AV block or symptomatic bradycardia develops, the dose should not be increased and specialist advice sought.

Verapamil is available on the PBS general schedule. It is used off-label for cluster headache (the PBS indications list cardiac conditions), but its use is eTG-endorsed and standard Australian practice.

Second-line and refractory prevention

Galcanezumab (Emgality, an anti-CGRP monoclonal antibody) is TGA-registered for episodic cluster headache after the Goadsby 2019 NEJM RCT showed significant reduction in weekly attack frequency. However, galcanezumab is not PBS-listed for cluster headache in Australia as of 2026 — it is PBS-funded only for chronic migraine prevention. Private cost is approximately $650 per monthly dose; the manufacturer (Lilly) has a patient access programme. Galcanezumab must be specialist-initiated.

Lithium carbonate (600–1200 mg per day, targeting a trough level of 0.4–0.8 mmol/L) is a second-line option, particularly for chronic cluster headache. Narrow therapeutic index, regular level monitoring, and thyroid and renal function checks every six months are required. Specialist supervision is standard.

Topiramate 50–200 mg per day is an adjunct with modest evidence. It carries specific risks worth discussing: cognitive side effects (“brain fog”), kidney stones, and significant teratogenicity, which requires reliable contraception in people of reproductive potential.

Low-dose melatonin at bedtime has supporting evidence from circadian rationale studies and is safe and inexpensive — a reasonable adjunct per NPS MedicineWise.

For genuinely refractory chronic cluster headache, tertiary headache centres offer occipital nerve stimulation and sphenopalatine ganglion stimulation.

D. Australian operations

PBS and home oxygen access

PBS Authority Required sumatriptan injection for cluster headache allows dispensing per cluster bout — the authority must specify cluster headache (not migraine). Verapamil is PBS general — no authority is required, though it is prescribed off-label. Prednisolone and topiramate are also PBS general (topiramate under Streamlined Authority 4622 for migraine prophylaxis; off-label for cluster).

Domiciliary oxygen access varies by state:

New South Wales — EnableNSW (via enable.health.nsw.gov.au)
Victoria — Domiciliary Oxygen Therapy Service (via health.vic.gov.au)
Queensland — Oxygen Subsidy Scheme (via health.qld.gov.au)
Other states have equivalent programs; contact the local respiratory service

Where state programs have eligibility constraints, medical-grade oxygen cylinders and concentrators can be hired on GP prescription from AirLiquide, BOC, or Coregas. The script should specify 100% O₂, 12–15 L/min flow rate, non-rebreather mask, cluster headache diagnosis.

MBS items relevant to cluster headache

Standard GP consultations (items 23, 36, 44) apply. MRI brain is MBS-rebatable for “unexplained chronic headache” or “first or worst headache” under item 63007 on GP referral. ECG is item 11700. Neurology consultation items are 110 and 116. For ongoing chronic cluster headache with significant functional impact, a GP Chronic Condition Management Plan (GPCCMP, item 965; review item 967) supports coordinated allied-health referrals. A Mental Health Treatment Plan (item 2715) should be opened at diagnosis given the high suicidality rate — this funds up to 10 psychology sessions per year under the Better Access initiative.

E. Special populations

Older adults (onset after 50). New cluster headache after 50 warrants imaging to exclude giant cell arteritis, pituitary pathology, and other structural causes before confirming a primary diagnosis. The verapamil titration approach is the same, but cardiac monitoring is more important.

Pregnancy. Oxygen is safe. Subcutaneous sumatriptan carries a Class B1 designation in Australia — limited human data; most guidelines support cautious use when benefit outweighs risk, in consultation with obstetric medicine. Verapamil is generally avoided in the first trimester; the decision requires specialist input.

Chronic cluster headache. Around 15% of those with cluster headache have the chronic form, where bouts persist beyond one year without remission. Verapamil doses up to 960 mg per day may be needed under specialist supervision, with strict ECG monitoring. These patients benefit from referral to a dedicated headache service.

Smoking and alcohol. More than 80% of people with cluster headache have a smoking history; while causality is uncertain, smoking cessation support is appropriate. Alcohol abstinence during an active bout is essential — alcohol reliably triggers attacks during a cluster period (not during remission) through a mechanism likely related to vasodilatation.

When to escalate

Refer urgently to the emergency department for:

First or worst headache (to exclude subarachnoid haemorrhage or other intracranial emergency)
Neurological deficit, papilloedema, fever, or neck stiffness with headache
Active suicidal ideation

Refer to neurology for:

All new diagnoses of cluster headache (Australian Prescriber recommends specialist confirmation)
Failure to respond to oxygen plus sumatriptan
Suspected secondary (symptomatic) cluster headache
Refractory bout failing verapamil up to 480 mg per day
Consideration of galcanezumab, lithium, or greater occipital nerve block

Refer to mental health services (Mental Health Care Plan) at diagnosis, and reassess at every visit during an active bout.

What this article is and is not

This is general health information drawn from current Australian general practice guidelines — Therapeutic Guidelines Neurology, the Australian Medicines Handbook, NPS MedicineWise, Australian Prescriber — and from the European Academy of Neurology 2023 cluster headache guideline and key clinical trials. It is not personal medical advice and does not create a doctor–patient relationship. Decisions about treatment — including which medications to use, how to titrate verapamil, and how to access oxygen — are made with your own general practitioner and treating clinicians.

For Australian consumer-friendly information: Headache Australia, HealthDirect — cluster headache, Better Health Channel — headaches.

For mental health support during a cluster bout: Lifeline 13 11 14, Beyond Blue 1300 22 4636.

Sources cited

Frequently asked questions

How is cluster headache different from migraine?

The key difference is behaviour during an attack: migraine patients lie still and avoid movement; cluster headache patients pace, rock, or bang their head — the pain is that severe. Cluster attacks also last only 15–180 minutes (migraine lasts 4–72 hours), occur strictly on one side almost always, cause prominent eye watering, redness, nasal congestion, and drooping of the eyelid on the pain side. Cluster headache is also strongly circadian — attacks tend to strike at the same time each day, often waking people from sleep at 1–3 am during a cluster bout.
Why is oxygen the first treatment for cluster headache attacks?

High-flow oxygen — 100% via a non-rebreather mask at 12–15 L/min for 15 minutes, sitting upright — aborts around 70% of attacks within 15 minutes, with no dependence risk, no medication-overuse risk, and no contraindication in pregnancy or cardiac disease. The oxygen must be high-flow through a non-rebreather mask; low-flow oxygen through nasal cannulae is not effective and a failed trial at low flow does not rule out the diagnosis. Subcutaneous sumatriptan is the complementary acute treatment when oxygen gives partial relief.
How is verapamil used to prevent cluster headache?

Verapamil is the first-line preventive for cluster headache. It is started at 80 mg three times daily (240 mg total daily) and increased by 80 mg every 10–14 days until attacks suppress or side effects limit the dose. The usual effective dose is 240–480 mg per day. An ECG must be performed before starting and before every dose increase, because verapamil can prolong the PR interval, cause AV block, or slow the heart rate in around 20% of patients. These side effects can appear at any dose, sometimes with a delay — making the ECG monitoring non-negotiable.
What is a cluster bout, and how long does it last?

A cluster bout (or cluster period) is the active phase when attacks occur daily, often at fixed times, for weeks to months. Most people have episodic cluster headache — bouts last 7 days to one year, then give way to remission periods of at least three months. About 15% have chronic cluster headache, where bouts persist for more than one year without a sustained remission. Between bouts, people feel completely well. Bouts tend to return in the same season each year, often spring or autumn. Alcohol reliably triggers attacks during an active bout but not during remission — a useful diagnostic clue.
How do I get home oxygen for cluster headache in Australia?

Domiciliary oxygen for cluster headache is available through state-based respiratory subsidy programs — EnableNSW in New South Wales, Domiciliary Oxygen Therapy Service in Victoria, Queensland's Oxygen Subsidy Scheme, and similar programs in other states. Your GP writes a script confirming the diagnosis, attack frequency, and oxygen flow rate required. Where a state program doesn't cover cluster headache specifically, medical-grade oxygen cylinders can be hired from companies such as AirLiquide, BOC, and Coregas on a GP prescription. Both a cylinder and a non-rebreather mask are needed — the mask is as important as the oxygen itself.

Source quality

Sources grouped by evidence tier. AU primary tier first; international where AU is silent or lagging; named-author reconstruction where guidelines have not yet caught up. How tiers work.