What is SNOOP10 and which headaches need emergency care?

SNOOP10 is a structured red-flag screen used in general practice at every new or changed headache encounter. The letters prompt the GP to ask about Systemic features (fever, weight loss, immunosuppression), Neurological deficit (focal weakness, vision loss, altered consciousness), sudden Onset ('thunderclap' peaking in under a minute), age Over 50, Pattern change, Positional worsening, Valsalva-Precipitated pain, Prior history of cancer or HIV, Pregnancy, Painkiller overuse, and Papilloedema. Thunderclap headache, fever with neck stiffness, or focal neurology require immediate transfer to the emergency department — do not wait for a scan in the clinic.

My head came on suddenly and severely — could it be serious?

A sudden severe headache that peaks within one minute — often described as the worst of a person's life — is a thunderclap headache. The most important cause to exclude is subarachnoid haemorrhage (bleeding on the surface of the brain), which can be life-threatening. Non-contrast CT of the head within 6 hours of onset is approximately 100% sensitive for this on a modern scanner. If the CT is negative but symptoms are still concerning, a lumbar puncture to look for xanthochromia (blood breakdown products in the fluid) is needed. Always call triple zero (000) or go immediately to the emergency department for thunderclap headache.

Do I need a brain scan for my headaches?

Most people with recurring headaches — especially those that match migraine or tension-type patterns, occur on a background of a clear normal examination, and have no red flags — do not need brain imaging. Australian and international guidelines including Choosing Wisely Australia and NICE both recommend against routine neuroimaging in classical primary headache with a normal neurological examination. Imaging is reserved for when any SNOOP10 red flag is present. Scans carry a small but real risk of finding incidental abnormalities that require further investigation without changing headache management, so the decision should be guided by clinical assessment rather than reassurance alone.

What is medication-overuse headache and how does it develop?

Medication-overuse headache (MOH) is a common and often underdiagnosed form of chronic daily headache that develops when acute pain-relieving medications are used too frequently. The threshold is simple analgesics (paracetamol, NSAIDs, aspirin) on 15 or more days per month, or triptans, opioids, or ergotamines on 10 or more days per month, for more than 3 months running. The brain adapts to frequent medication by lowering its pain threshold. Treatment involves a supervised withdrawal of the overused agent — headache typically worsens for the first week before improving — together with bridging anti-inflammatory treatment and starting a preventive medication.

What triggers migraines and what can I do to reduce them?

Common migraine triggers include sleep deprivation or disruption, skipped meals, dehydration, alcohol (particularly red wine and beer), hormonal fluctuation around menstruation, significant stress and the post-stress let-down period, bright light, strong smells, and weather changes. A headache diary — apps such as Migraine Buddy or N1-Headache work well — helps identify personal triggers. Regular aerobic exercise of at least 150 minutes per week has evidence equivalent to topiramate for episodic migraine prevention. Keeping consistent sleep and meal schedules, managing stress, and limiting caffeine intake (while avoiding abrupt withdrawal) are the lifestyle cornerstones.

Headache — primary and secondary

Headache: red-flag screening and workup — the AU general-practice approach

By Dr HB Lo, FACRRM Reviewed 6 July 2026 11 min read

Headache accounts for roughly 3% of all GP encounters — around 95% are primary (migraine, tension-type, cluster) and benign. The SNOOP10 red-flag framework identifies the dangerous minority of secondary headaches requiring urgent investigation or immediate transfer.

Must-not-miss secondary causes include subarachnoid haemorrhage (thunderclap onset peaking within one minute), bacterial meningitis, giant cell arteritis in patients over 50, cervical artery dissection, and brain tumour.

Once red flags are excluded, the headache type is classified by ICHD-3 criteria and managed with targeted acute treatment, lifestyle optimisation, and prophylaxis when headaches are frequent or disabling.

What headache assessment in general practice is really about

Headache is one of the most common reasons Australians attend their GP, accounting for roughly 3% of all encounters in BEACH data. The vast majority — approximately 95% — are primary headaches: migraine, tension-type, or cluster. These are benign, recurrent, and manageable. The remaining 5% are secondary headaches caused by an underlying condition, and a small but critical subset of those are immediately life-threatening.

The GP’s core task is not to diagnose every headache but to apply a structured red-flag screen at every new or changed headache encounter, exclude dangerous secondary causes, and then classify the primary headache type accurately so treatment can be targeted. Australian Prescriber describes this systematic approach as the cornerstone of safe headache practice in general practice.

A. Core clinical — the AU general-practice framework

History: SOCRATES and SNOOP10

Every headache consultation begins with SOCRATES — Site, Onset, Character, Radiation, Associations, Time-course, Exacerbating and relieving factors, and Severity. Layered over this clinical description is the SNOOP10 red-flag screen (Dodick, Neurol Clin 2010), which should be applied at every new or changed headache presentation.

Letter	Feature	Suspect
Systemic	Fever, weight loss, immunocompromise, malignancy, anticoagulation	Meningitis, abscess, metastasis
Neurological	Focal deficit, altered consciousness, papilloedema, seizure	Mass, stroke, idiopathic intracranial hypertension
Onset	Thunderclap — peaks within one minute	Subarachnoid haemorrhage, cervical artery dissection
Older	First headache after age 50	Giant cell arteritis, tumour
Pattern	New character or escalation in established headache	Imaging if persistent
Positional	Supine or Valsalva worse → raised ICP; standing worse → low CSF pressure	Mass lesion, CSF leak
Precipitated	Coughing, straining, exertion, sexual activity	Posterior fossa lesion, RCVS
Prior history	Cancer, HIV, anticoagulation, trauma	Metastasis, abscess, haemorrhage
Pregnancy / postpartum	Third trimester or first 6 weeks after birth	Pre-eclampsia, cerebral venous thrombosis, RCVS
Painkiller overuse	Simple analgesic ≥15 days/month or triptan/opioid ≥10 days/month for >3 months	Medication-overuse headache
Papilloedema	Fundoscopic finding	IIH, mass lesion, malignant hypertension

Any positive SNOOP10 flag warrants prompt investigation or urgent transfer, depending on severity.

Examination

Vitals — blood pressure (hypertensive emergency, pre-eclampsia), temperature (meningitis), and heart rate — provide the immediate clinical context. Australian Prescriber and ANZAN both emphasise that fundoscopy is frequently the most cost-effective single step in headache examination: look for papilloedema, retinal haemorrhage, and optic atrophy. Assess neck stiffness and Kernig and Brudzinski signs when meningism is possible. Check cranial nerves — visual fields and acuity, pupil reactions, extraocular movements, facial power and sensation. Palpate temporal arteries in any patient over 50. Assess gait, coordination, power, and plantar reflexes.

Investigations — selective and guided by SNOOP10

Routine neuroimaging is not indicated in classical primary headache with a normal examination and no red flags — per NICE NG150, ANZAN, and Choosing Wisely Australia. When red flags are present, investigation follows the specific flag:

Thunderclap headache → non-contrast CT head immediately. Perry BMJ 2011 demonstrated approximately 100% sensitivity for subarachnoid haemorrhage within 6 hours on a modern scanner with expert reading. If CT is negative and onset was more than 6 hours prior, or clinical suspicion remains high, lumbar puncture for xanthochromia is required.
Focal neurology or papilloedema → MRI brain ± contrast (MBS item 63007).
Suspected giant cell arteritis → ESR and CRP urgently; start prednisolone before biopsy if visual threat is present; temporal artery ultrasound or biopsy for confirmation.
Suspected cerebral venous sinus thrombosis → MRI plus MRV.
Suspected cervical artery dissection → CTA or MRA of the neck.
Suspected meningitis → IV ceftriaxone 2 g and dexamethasone within 30 minutes; do not delay for LP or CT.
Suspected carbon monoxide poisoning → carboxyhaemoglobin level; multiple household members with headache and a faulty heater is the classic scenario.

B. Dangerous secondary headaches — the must-not-miss list

Subarachnoid haemorrhage

The classic presentation is a thunderclap headache — often “the worst headache of my life” — that peaks within one minute. Associated features include neck pain or stiffness, photophobia, nausea, and sometimes brief loss of consciousness or a seizure. Non-contrast CT within 6 hours has approximately 100% sensitivity (Perry BMJ 2011); a negative CT after 6 hours requires lumbar puncture for xanthochromia. Any thunderclap headache is a Category-1 transfer — do not attempt outpatient investigation. The Ottawa SAH Rule provides structured decision support when the clinical picture is borderline.

Bacterial meningitis

The classic triad is fever, neck stiffness, and altered mental state — though all three are present in fewer than half of cases. Petechial or purpuric rash suggests meningococcal disease, which can progress to septic shock within hours. Do not delay treatment for imaging or lumbar puncture: give IV ceftriaxone 2 g and dexamethasone within 30 minutes of clinical diagnosis. Therapeutic Guidelines recommends benzylpenicillin and aciclovir be added to cover encephalitis if viral aetiology cannot be excluded. Notify public health promptly — meningococcal disease is notifiable in all Australian states.

Giant cell arteritis

Giant cell arteritis (GCA) should be considered in any patient over 50 with a new headache. Scalp tenderness, jaw claudication, visual disturbance, and features of polymyalgia rheumatica raise the probability substantially. ESR and CRP should be requested urgently; if visual loss or amaurosis fugax is present, start prednisolone 60 mg daily immediately without waiting for temporal artery biopsy. Permanent visual loss from anterior ischaemic optic neuropathy can be prevented when corticosteroids are started promptly. RACGP guidelines support empirical treatment before histological confirmation when clinical suspicion is high.

Medication-overuse headache

Medication-overuse headache (MOH) is chronic daily headache in a patient with established primary headache who uses acute analgesics on 15 or more days per month (simple analgesics) or 10 or more days per month (triptans, opioids, ergotamines) for more than 3 months. The pathophysiology involves central sensitisation driven by frequent analgesic exposure. Treatment requires supervised withdrawal of the overused agent, bridging with scheduled naproxen 250–500 mg twice daily for 2–4 weeks, and initiation of preventive therapy. Patients should be counselled that headache typically worsens in the first week before improving. ICHD-3 criteria and NPS MedicineWise guidance both emphasise that counting headache days in a diary is essential for diagnosis and monitoring.

Other dangerous secondary causes

Cervical artery dissection presents with unilateral neck or occipital pain, Horner syndrome (ipsilateral ptosis, miosis, and anhidrosis), pulsatile tinnitus, or posterior-circulation TIA or stroke symptoms — investigate with CTA or MRA of the neck. Idiopathic intracranial hypertension (IIH) typically affects obese reproductive-age women with daily headache, transient visual obscurations, pulsatile tinnitus, and papilloedema — MRI with MRV and lumbar puncture with opening pressure confirm the diagnosis. Cerebral venous sinus thrombosis is associated with pregnancy, combined oral contraceptive use, dehydration, and inherited thrombophilia — subacute headache with seizures or focal deficit is the presentation. Acute angle-closure glaucoma produces periocular pain, nausea, a red eye, and a mid-dilated fixed pupil — urgent tonometry and ophthalmology referral are needed.

C. Primary headache types and management

Migraine

Migraine affects approximately 14% of Australians and is the leading cause of disability in women under 50 globally. ICHD-3 diagnostic criteria require at least five attacks of 4–72 hours’ duration, at least two of (unilateral location, pulsating quality, moderate–severe intensity, aggravation by routine physical activity), and at least one of (nausea or vomiting, photophobia and phonophobia). Aura — typically visual and reversible over 20–60 minutes — occurs in approximately one third of patients.

Acute treatment per Therapeutic Guidelines: triptans (sumatriptan, rizatriptan, eletriptan — PBS Authority Streamlined) are first-line for moderate–severe attacks; NSAIDs (ibuprofen 400–600 mg, naproxen 500 mg) for mild–moderate attacks; antiemetics (metoclopramide, prochlorperazine) address nausea and improve analgesic absorption. Opioids should be avoided — they are poorly effective and substantially increase the risk of MOH.

Prevention is indicated when attacks are four or more per month, severely disabling, or failing acute treatment consistently. First-line preventive options include propranolol, amitriptyline, topiramate (Authority Required on PBS), and candesartan off-label. CGRP monoclonal antibodies (erenumab, fremanezumab, galcanezumab) are PBS Authority Required for chronic migraine (15 or more days per month) after at least three prior preventive failures. Aerobic exercise at 150 minutes per week has been shown equivalent to topiramate for episodic migraine prevention (Varkey, Cephalalgia 2011), and Cochrane acupuncture meta-analysis (Linde 2016) found acupuncture at least as effective as prophylactic drugs for episodic migraine. Magnesium 400–600 mg/day and riboflavin 400 mg/day have moderate evidence as safe, low-cost adjuncts.

Tension-type headache

Tension-type headache is bilateral, pressing, mild–moderate in severity, not aggravated by routine activity, and lacks significant nausea — with photophobia or phonophobia present but not both. It responds to paracetamol or NSAIDs for episodic attacks. Chronic tension-type headache (15 or more days per month) warrants low-dose amitriptyline for prophylaxis and diary-keeping to screen for concurrent MOH. Stress management, regular sleep, and physiotherapy addressing cervical musculoskeletal factors are appropriate adjuncts.

Cluster headache

Cluster headache produces severe, strictly unilateral orbital or temporal pain lasting 15–180 minutes with ipsilateral autonomic features — lacrimation, conjunctival injection, ptosis, miosis, rhinorrhoea, or eyelid oedema — and marked restlessness. The circadian periodicity (attacks often waking patients at the same time each night) and episodic clustering over weeks with pain-free remission periods are diagnostically distinctive. Acute treatment: 100% oxygen at 12–15 L/min via non-rebreather mask and sumatriptan 6 mg subcutaneously (PBS Authority Streamlined) are both highly effective. Verapamil is first-line for prevention. Neurology referral is appropriate at diagnosis for management planning.

D. Australian operations

MBS items and GP billing

Headache assessment is billed under standard consultation items (23, 36, 44) according to duration and complexity. Non-contrast CT head is MBS item 56001; MRI brain (with or without contrast) is item 63007. Pathology for ESR, CRP, and FBC is billed under standard pathology items. Mental Health Treatment Plans (items 2715/2717) apply when chronic migraine substantially impacts mood, or when comorbid anxiety or depression requires psychological input — up to 10 subsidised psychology sessions per year under Better Access.

PBS prescribing

Therapeutic Guidelines informs the following PBS landscape: triptans (sumatriptan, rizatriptan, eletriptan) are Authority Streamlined for migraine acute management. Topiramate is Authority Required for migraine prophylaxis. CGRP monoclonal antibodies (erenumab, fremanezumab, galcanezumab) require specialist-initiated Authority for chronic migraine after three prior preventive failures. Verapamil is general schedule for cluster headache prevention; lithium is Authority Required for chronic cluster. Prednisolone for GCA is available under emergency Authority provisions.

Patient resources and headache diaries

Migraine & Headache Australia provides current patient resources and a practitioner directory for CBT-informed headache management. NPS MedicineWise offers consumer-facing headache and migraine information. Headache diaries — the Migraine Buddy app or paper alternatives — are the backbone of every headache consultation, improving diagnostic accuracy, quantifying medication use to detect MOH, and identifying triggers including sleep irregularity, dehydration, skipped meals, alcohol, and menstrual cycle fluctuation.

E. Special populations

Older adults. Any new headache after age 50 requires systematic exclusion of GCA, intracranial neoplasm, and cerebrovascular disease before attributing the headache to a primary cause. Analgesic choices must account for renal function, anticoagulation use, and falls risk. Opioids and tricyclics carry particular risk in older patients; topiramate causes cognitive effects that may be poorly tolerated.

Women of reproductive age and pregnancy. Migraine commonly worsens perimenstrually — oestrogen withdrawal is the trigger — and often in the first trimester, then frequently improves in the second and third trimesters. Most triptans are not recommended in pregnancy; paracetamol is the first-line analgesic. Postpartum headache can reflect pre-eclampsia, cerebral venous sinus thrombosis, or a low-CSF-pressure headache following epidural anaesthesia — the clinical features guide investigation. Migraine with aura slightly increases ischaemic stroke risk, and combined oral contraceptives are generally avoided in this group.

Children and adolescents. Migraine is common in children and often under-diagnosed. Paediatric migraine may last as briefly as 1 hour (ICHD-3 allows 2 hours in children), is more often bilateral and frontal, and has prominent gastrointestinal features. Ibuprofen is first-line acute therapy. Paediatric neurology referral is appropriate when headaches are frequent, disabling, or associated with atypical features. Perimenarchal migraine worsening in adolescent girls often requires both short-term management and a longer-term prevention strategy.

ATSI Australians. Headache as a presenting complaint in Aboriginal and Torres Strait Islander patients warrants the same SNOOP10 framework. Higher rates of hypertension, cardiovascular disease, and diabetes in this population mean secondary causes should be actively considered even in younger patients. Cultural safety and a trusting therapeutic relationship support more complete history-taking.

When to escalate

Transfer to the emergency department immediately by ambulance for:

Thunderclap headache of any description
Suspected bacterial meningitis (fever + neck stiffness + altered mental state or rash)
Focal neurological deficit of any kind
Altered or fluctuating consciousness
Papilloedema on fundoscopy
Suspected GCA with visual symptoms or amaurosis fugax
Severe headache in pregnancy or postpartum
Post-traumatic headache with neurological deficit

Same-day specialist contact for:

New headache over 50 with elevated ESR/CRP and suspected GCA without visual threat
Suspected cervical artery dissection
Suspected idiopathic intracranial hypertension
Refractory cluster headache

Routine neurology referral for:

Chronic migraine failing two preventive medications
Atypical aura (prolonged, motor, basilar, retinal)
Suspected hemicrania continua (indomethacin-responsive)
Trigeminal neuralgia
New daily persistent headache (diagnosis of exclusion after secondary work-up)

What this article is and is not

This is general health information drawn from Australian general-practice guidelines — RACGP, Therapeutic Guidelines, Australian Prescriber, ANZAN, ICHD-3, Choosing Wisely Australia, NICE NG150 — and peer-reviewed neurology literature. It is not personal medical advice and does not constitute a clinical consultation. Assessment and management of specific headache presentations requires the judgement of a qualified medical practitioner with access to the full clinical picture.

For consumer-friendly information: HealthDirect — Headache, Better Health Channel — Headaches, Migraine & Headache Australia.

For sudden, severe, or concerning headache — particularly one that comes on in seconds: call triple zero (000) or go immediately to the nearest emergency department.

Sources cited

Frequently asked questions

What is SNOOP10 and which headaches need emergency care?

SNOOP10 is a structured red-flag screen used in general practice at every new or changed headache encounter. The letters prompt the GP to ask about Systemic features (fever, weight loss, immunosuppression), Neurological deficit (focal weakness, vision loss, altered consciousness), sudden Onset ('thunderclap' peaking in under a minute), age Over 50, Pattern change, Positional worsening, Valsalva-Precipitated pain, Prior history of cancer or HIV, Pregnancy, Painkiller overuse, and Papilloedema. Thunderclap headache, fever with neck stiffness, or focal neurology require immediate transfer to the emergency department — do not wait for a scan in the clinic.
My head came on suddenly and severely — could it be serious?

A sudden severe headache that peaks within one minute — often described as the worst of a person's life — is a thunderclap headache. The most important cause to exclude is subarachnoid haemorrhage (bleeding on the surface of the brain), which can be life-threatening. Non-contrast CT of the head within 6 hours of onset is approximately 100% sensitive for this on a modern scanner. If the CT is negative but symptoms are still concerning, a lumbar puncture to look for xanthochromia (blood breakdown products in the fluid) is needed. Always call triple zero (000) or go immediately to the emergency department for thunderclap headache.
Do I need a brain scan for my headaches?

Most people with recurring headaches — especially those that match migraine or tension-type patterns, occur on a background of a clear normal examination, and have no red flags — do not need brain imaging. Australian and international guidelines including Choosing Wisely Australia and NICE both recommend against routine neuroimaging in classical primary headache with a normal neurological examination. Imaging is reserved for when any SNOOP10 red flag is present. Scans carry a small but real risk of finding incidental abnormalities that require further investigation without changing headache management, so the decision should be guided by clinical assessment rather than reassurance alone.
What is medication-overuse headache and how does it develop?

Medication-overuse headache (MOH) is a common and often underdiagnosed form of chronic daily headache that develops when acute pain-relieving medications are used too frequently. The threshold is simple analgesics (paracetamol, NSAIDs, aspirin) on 15 or more days per month, or triptans, opioids, or ergotamines on 10 or more days per month, for more than 3 months running. The brain adapts to frequent medication by lowering its pain threshold. Treatment involves a supervised withdrawal of the overused agent — headache typically worsens for the first week before improving — together with bridging anti-inflammatory treatment and starting a preventive medication.
What triggers migraines and what can I do to reduce them?

Common migraine triggers include sleep deprivation or disruption, skipped meals, dehydration, alcohol (particularly red wine and beer), hormonal fluctuation around menstruation, significant stress and the post-stress let-down period, bright light, strong smells, and weather changes. A headache diary — apps such as Migraine Buddy or N1-Headache work well — helps identify personal triggers. Regular aerobic exercise of at least 150 minutes per week has evidence equivalent to topiramate for episodic migraine prevention. Keeping consistent sleep and meal schedules, managing stress, and limiting caffeine intake (while avoiding abrupt withdrawal) are the lifestyle cornerstones.

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.