Headache in the emergency department
Most headaches are benign, but a few kill. Ask how fast it peaked, look for red flags, examine the fundi, and treat meningitis before you scan.
A 42-year-old woman was lifting a heavy bucket when she felt "like someone hit me with a cricket bat" on the back of the head. The pain was at its worst within a minute. She vomited twice. Now she is alert, with a stiff neck. BP 168/92. No fever.
Can you give her painkillers and send her home if she settles?
- How fast did it peak?Maximum within a minute (thunderclap) is subarachnoid haemorrhage until proven otherwise.
- Full observationsBP, temperature, GCS, SpO₂, sugar.
- Red flagsThunderclap, fever and neck stiffness, focal signs, fits, drowsiness, papilloedema, over 50 with a new headache, pregnancy.
- Examine properlyNeurology, neck stiffness, fundi, temporal arteries, eyes (red eye, fixed pupil).
- Meningitis possible?Ceftriaxone now, before CT or LP. See Meningitis.
- CT head for red flagsThen LP if indicated.
- Treat the painParacetamol or ibuprofen with metoclopramide. Avoid opioids for migraine.
- Discharge safelyOnly with a clear diagnosis and return advice.
- Thunderclap onset
- Fever with neck stiffness, rash or confusion
- Focal neurology, fits or reduced GCS
- Papilloedema, or worse lying down with vomiting
- Over 50 with jaw pain on chewing or visual symptoms
- Pregnant or after delivery with high BP
- Subarachnoid haemorrhage
- Meningitis and encephalitis
- Raised intracranial pressure (tumour, abscess, TB)
- Giant cell arteritis
- Cerebral venous sinus thrombosis
- Pre-eclampsia
- Carbon monoxide poisoning
- Acute angle-closure glaucoma
| Thunderclap | Peak within about 1 minute: CT head urgently |
| CT within 6 hours of onset, normal | SAH very unlikely if a good scanner and expert report |
| CT after 6 hours, normal | LP at least 12 hours after onset for xanthochromia |
| Suspected giant cell arteritis | Prednisolone the same day (dose in the treatment section) |
| Migraine | Simple painkiller plus metoclopramide |
Check every dose against a current drug reference and your hospital protocol.
On this page
Red flags
- Subarachnoid haemorrhage
- Also venous sinus thrombosis, dissection, pituitary apoplexy
- CT now
- Meningitis or encephalitis
- Antibiotics first
- Raised pressure: tumour, abscess, TB, bleed
- CT
- Giant cell arteritis
- ESR, CRP, steroids today
- Carbon monoxide from gas heaters, angithis (charcoal braziers) and generators in closed rooms in winter: headache, dizziness, vomiting, often several family members at once. High-flow oxygen; check a carboxyhaemoglobin level on a blood gas if available. Pulse oximetry reads falsely normal.
- Pre-eclampsia in pregnancy after 20 weeks or up to 6 weeks after delivery: check BP and urine.
- Venous sinus thrombosis after delivery or on the pill: headache, fits, focal signs.
- TB meningitis: weeks of headache, fever and weight loss.
- Acute angle-closure glaucoma: red painful eye, blurred vision with haloes, fixed mid-dilated pupil, vomiting.
Subarachnoid haemorrhage
- Usually from a ruptured berry aneurysm at the circle of Willis.
- Sudden severe headache (often "the worst ever"), vomiting, neck stiffness (may take hours), brief loss of consciousness, fits.
- Do not give a sedating painkiller and send home. A small "warning bleed" can be followed by a fatal rupture.
- CT head without contrastAs soon as possible.
- Bleed on CTNeurosurgery now. BP control, nimodipine and supportive care as directed.
- CT normal and done within 6 hours of onsetSAH very unlikely if reported by an experienced radiologist on a modern scanner. Senior decision.
- CT normal but done after 6 hoursLP at least 12 hours after onset. Look for xanthochromia (yellow CSF from broken-down blood).
- LP normalSAH excluded. Consider other causes.
Other causes
| Cause | Features | Action |
|---|---|---|
| Migraine | Throbbing, one-sided, nausea, light sensitivity, previous similar attacks, aura | Simple painkillers and antiemetic |
| Tension-type | Band-like, both sides, no vomiting | Reassurance, simple painkillers |
| Medication overuse | Daily headache with frequent painkiller use | Stop the overused painkiller |
| Cluster | Severe pain around one eye, red watery eye, attacks of 15–180 minutes | High-flow oxygen, sumatriptan injection |
| Sinusitis | Facial pain, blocked nose, worse bending forward | Analgesia; see Sinusitis |
| Hypertensive emergency | Very high BP with confusion, vision change | See Hypertensive emergency |
| Idiopathic intracranial hypertension | Young overweight woman, papilloedema, worse lying down | Neurology, LP with pressure |
Examination
- GCS, pupils, full neurological examination.
- Fundoscopy for papilloedema in every serious headache.
- Neck stiffness, rash (meningococcal), temperature.
- Temporal artery tenderness or thickening in those over 50.
- Eyes: red eye, cloudy cornea, fixed mid-dilated pupil (glaucoma).
- BP, and pregnancy status in women.
Treatment
Avoid opioids and painkiller injections such as tramadol or pethidine for migraine. They work poorly, cause rebound headaches and dependence.
Discharge
- Clear diagnosis, pain controlled, normal examination, no red flags.
- Return immediately if: sudden severe headache, fever with neck stiffness, drowsiness, fits, weakness, vision problems.
- Migraine: avoid overusing painkillers (no more than 2–3 days a week). Preventive treatment through the clinic if frequent.
Common mistakes
- Calling a thunderclap headache "migraine" because the pain settled with an injection.
- Doing an LP at 4 hours to "exclude SAH".
- Waiting for CT before giving antibiotics in suspected meningitis.
- Not looking at the fundi.
- Missing carbon monoxide when a whole family has headaches on a winter morning.
- Missing pre-eclampsia in a woman who delivered last week.
Frequently asked questions
What is a thunderclap headache?
A severe headache that reaches its maximum within about a minute. It needs urgent investigation for subarachnoid haemorrhage and other serious causes.
When is an LP needed for suspected subarachnoid haemorrhage?
When the CT is normal but was done more than 6 hours after the headache began. The LP is done at least 12 hours after onset to look for xanthochromia.
What are the red flags for headache?
Thunderclap onset, fever with neck stiffness, focal neurological signs, fits, reduced consciousness, papilloedema, a new headache over 50, pregnancy or the postpartum period, immunosuppression, and headache worse lying down with vomiting.
Test yourself
Exam-style questions on this guide, from our two question banks. Choose an answer to see why each option is right or wrong.
1. A patient has a sudden severe headache that began 9 hours ago. CT head is normal. What is the next step?
Answer: LP at 12 hours after onset. After 6 hours, a normal CT doesn't exclude SAH. LP at least 12 hours after onset looks for xanthochromia.
- Discharge home: Subarachnoid haemorrhage is not yet excluded.
- Repeat CT in 48 hours: Not the next step.
- LP immediately: Too early for xanthochromia.
- MRI brain next week: Delay.
2. A 70-year-old has a new headache, jaw pain on chewing and blurred vision. What should be done today?
Answer: High-dose prednisolone today. Giant cell arteritis with visual symptoms: start steroids the same day; biopsy can be done within 1–2 weeks of starting.
- CT head first: Doesn't change urgent steroid treatment.
- Refer to dentist: Jaw claudication is a feature of giant cell arteritis.
- Ibuprofen and review in a week: Risk of permanent blindness.
- Wait for temporal artery biopsy: Steroids must not be delayed.
3. A family of five all have headaches and vomiting on a winter morning. What should be suspected?
Answer: Carbon monoxide poisoning. A gas heater in a closed room can cause CO poisoning. Give high-flow oxygen and check carboxyhaemoglobin.
- Food poisoning: Less likely with headache dominant.
- Meningitis: Not all at once.
- Migraine: Not a family cluster.
- Viral gastroenteritis: Possible but the shared winter morning pattern suggests CO.
4. A 40-year-old has sudden ‘worst ever’ headache while lifting weights, with vomiting and neck stiffness. CT head at 12 hours is normal. What is the next step?
Answer: LP for xanthochromia. CT within 6 hours of headache onset is highly sensitive for SAH; after 6 hours, a normal CT should be followed by LP (≥ 12 hours after onset) for xanthochromia (bilirubin from red cell breakdown). If SAH confirmed, CT angiography to find the aneurysm (berry aneurysm, ADPKD, Ehlers–Danlos), nimodipine for vasospasm, and endovascular coiling or clipping.
- Discharge with analgesia: SAH is not excluded by a normal CT at 12 hours.
- MRI of the whole spine: Spinal MRI is not indicated.
- EEG and observation: EEG does not diagnose SAH.
5. A 72-year-old woman has new temporal headache, scalp tenderness, jaw claudication and transient blurred vision. ESR is 95 mm/h. What should be done first?
Answer: High-dose prednisolone today. Giant cell arteritis is a large-vessel vasculitis of people > 50, linked with polymyalgia rheumatica. Visual symptoms threaten permanent blindness (anterior ischaemic optic neuropathy). Start high-dose glucocorticoids immediately (IV methylprednisolone if visual loss), then confirm with temporal artery ultrasound (halo sign) or biopsy within 1–2 weeks (still diagnostic after steroids). Tocilizumab is steroid-sparing. Add aspirin per specialist advice.
- Wait for temporal artery biopsy: Waiting for biopsy risks blindness.
- NSAIDs and review: NSAIDs will not prevent visual loss.
- MRI brain before treatment: MRI delays treatment.
6. A man with angina has migraine with aura. Which drug should be avoided for his acute attacks?
Answer: Sumatriptan. Triptans are 5-HT1B/1D agonists that constrict cranial vessels and also coronary arteries. They are contraindicated in ischaemic heart disease, uncontrolled hypertension, previous stroke and hemiplegic migraine. Simple analgesics plus an antiemetic are suitable alternatives.
- Paracetamol: Safe.
- Ibuprofen: Usually safe (watch other risks).
- Metoclopramide: Antiemetic; safe.
- Aspirin: Safe for migraine; also antiplatelet.
7. A 72-year-old woman has new temporal headache, jaw claudication, scalp tenderness and transient visual loss. ESR is 95. What is the most important immediate step?
Answer: High-dose steroids now, then biopsy. Giant cell (temporal) arteritis is a granulomatous vasculitis of large and medium arteries in people over 50, linked to polymyalgia rheumatica. Visual loss from anterior ischaemic optic neuropathy can be permanent, so high-dose steroids start immediately; biopsy (skip lesions, giant cells) remains positive for 1–2 weeks after starting treatment.
- Wait for the biopsy first: Delay risks blindness.
- Aspirin alone: Not sufficient.
- MRI brain and review in a month: Dangerous delay.
- Methotrexate alone: Steroids are the first-line urgent treatment.
References and dose sources
- NICE CG150: Headaches in over 12s
- NICE NG228: Subarachnoid haemorrhage caused by a ruptured aneurysm
- International Classification of Headache Disorders (ICHD-3)
- NICE NG240 — meningitis & meningococcal disease
- BSR — giant cell arteritis
- NICE NG133 — hypertension in pregnancy
- Ceftriaxone dosing: Drugs.com: Ceftriaxone dosage (see also our ceftriaxone dose page)
- Dexamethasone dosing: Drugs.com: Dexamethasone dosage (see also our dexamethasone dose page)
- Aciclovir dosing: Drugs.com: Acyclovir (aciclovir) dosage (see also our aciclovir dose page)
- Prednisolone dosing: Drugs.com: Prednisolone dosage (see also our prednisolone dose page)
- Paracetamol dosing: Drugs.com: Acetaminophen (paracetamol) dosage (see also our paracetamol dose page)
- Ibuprofen dosing: Drugs.com: Ibuprofen dosage (see also our ibuprofen dose page)
- Metoclopramide dosing: Drugs.com: Metoclopramide dosage (see also our metoclopramide dose page)
- Sumatriptan dosing: Drugs.com: Sumatriptan dosage (see also our sumatriptan dose page)
International guidance is linked where it reflects good practice. Where your hospital’s protocol differs, follow your hospital.