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Acute Severe Headache: Migraine vs Red Flags
A triage guide for community pharmacists on distinguishing primary headache disorders from serious secondary causes requiring emergency or urgent referral.
Why this matters
Headache is one of the most common presentations at a pharmacy counter, and the vast majority are benign. Tension-type headache, migraine, and cluster headache are primary conditions with recognised patterns that pharmacists can identify and manage. However, a small number of headaches are secondary to serious pathology, and missing them carries significant risk.
The most critical condition to recognise is subarachnoid haemorrhage, which presents as a thunderclap headache: sudden and severe, reaching maximum intensity within 5 minutes, described as the worst headache of the patient's life.1 Raised intracranial pressure, meningitis, giant cell arteritis, and hypertensive crisis are further secondary causes. Community pharmacists are often the first point of contact and must know which features demand immediate action.
Red flags vs more likely benign
| Feature | More likely benign | Red flag ⚠ |
|---|---|---|
| Onset | Gradual, over minutes to hours | Thunderclap: reaches maximum intensity within 5 minutes; worst-ever headache1 |
| Severity | Mild to moderate (tension) or moderate to severe (migraine) | Worst headache of life; described as unprecedented by the patient |
| Pattern | Consistent with known personal headache history | New type of headache, substantial change from usual character, or progressive daily headache worsening over weeks |
| Fever | No associated fever | Worsening headache with fever: possible meningitis or encephalitis5 |
| Neurology | None, or fully reversible migraine aura lasting 5 to 60 minutes | New neurological deficit, confusion, personality change, or impaired consciousness |
| Neck stiffness / rash | None | Neck stiffness, photophobia, or non-blanching rash with headache and fever: suspected meningitis or meningococcal disease; rash may be absent5 |
| Visual symptoms | Migraine aura: visual disturbance fully resolving within 60 minutes | New monocular visual loss, diplopia, amaurosis fugax, or acute visual disturbance at any age: same-day urgent assessment for possible TIA, retinal artery occlusion, or other emergency. In patients aged 50 or over with jaw pain or scalp tenderness, also consider giant cell arteritis: treat as an emergency if visual loss is present4 |
| Trigger | Stress, dietary, menstrual, or sleep-related triggers | Cough, Valsalva, exertion, or sneezing; or headache worsening on lying down or bending forward |
| Raised intracranial pressure | Headache without waking pattern or vomiting | Headache worse on waking, on bending forward, or lying down; associated vomiting without nausea; or a recent optician report of swollen optic discs |
| Pregnancy / postpartum | No current pregnancy or recent childbirth | New headache during pregnancy or within 6 weeks of delivery: risk of cerebral venous thrombosis or pre-eclampsia |
| Head injury | No recent head injury | New headache following head injury with any high-risk feature: loss of consciousness, vomiting, confusion, worsening headache, seizure, neurological deficit, or anticoagulant use |
| Immunosuppression | Immunocompetent, no known malignancy | New headache in a patient with known cancer, immunosuppression, or systemic symptoms such as weight loss or night sweats: exclude intracranial metastases or opportunistic infection |
| Age / scalp | Any age; no scalp tenderness or jaw pain | Age 50 or over with new temporal headache, jaw pain on chewing, or scalp tenderness: possible giant cell arteritis4 |
What to do in pharmacy
Call 999 immediately for any thunderclap headache: a sudden, severe headache reaching maximum intensity within 5 minutes, especially if described as the worst headache of the patient's life.1 Also call 999 for headache with impaired consciousness, a new neurological deficit, or seizure. Call 999 for any suspected meningitis or meningococcal disease: a headache with fever and any of neck stiffness, photophobia, non-blanching rash, confusion, or rapid deterioration. Rash may be absent, particularly early in meningococcal disease.5 Call 999 for a blood pressure above 180/120 mmHg accompanied by any of confusion, chest pain, breathlessness, neurological symptoms, or visual disturbance: this represents a hypertensive emergency.1 Do not let analgesia supply delay 999 activation. Advise the patient not to drive or make their own way to hospital.
Refer for same-day urgent assessment for any new headache with red flag features that does not require 999. Headache triggered by cough, Valsalva, exertion, or sneezing; new headache with symptoms of raised intracranial pressure; new headache in a patient with known cancer or immunosuppression; and any headache that has substantially changed in character all require same-day A&E or GP review. New monocular visual loss, diplopia, or amaurosis fugax at any age requires same-day urgent assessment for TIA or retinal emergency. In patients aged 50 or over with new temporal headache, jaw pain on chewing, or scalp tenderness, refer urgently for possible giant cell arteritis.4 If visual symptoms are also present, treat as a same-day emergency: untreated giant cell arteritis can cause sudden irreversible sight loss within hours. Do not delay referral to await blood results. New headache during pregnancy or in the postpartum period requires urgent maternity or obstetric triage to exclude cerebral venous thrombosis and pre-eclampsia; call 999 if accompanied by visual disturbance, severe hypertension, or confusion. Cluster headache does not respond to standard OTC analgesics: refer patients with suspected new cluster headache to their GP for specialist assessment. Check blood pressure in any patient presenting with severe headache. A raised blood pressure above 180/120 mmHg without symptoms warrants same-day GP review; with symptoms, call 999 (see Emergency above).
Self-care is appropriate for an established, recognised migraine or tension-type headache consistent with the patient's previous pattern and with no red flag features. For tension-type headache: ibuprofen or paracetamol. Aspirin 300 to 900 mg is an option for adults, but must not be supplied to children under 16 due to the risk of Reye's syndrome.2 For migraine: aspirin 900 mg (adults only), ibuprofen 400 mg, or paracetamol.2 Opioids and codeine-containing analgesics should be avoided for migraine and headache: they offer limited benefit and increase the risk of medication overuse headache.3 Before supplying sumatriptan 50 mg (Imigran Recovery), confirm: the patient has a pre-existing confirmed migraine diagnosis (not a new or atypical headache); they are aged 18 to 65; there are no cardiovascular risk factors or liver disease; they are not pregnant or breastfeeding; and there is no concurrent use of MAOIs, other triptans, or ergots. Concurrent SSRIs or SNRIs are a caution rather than an absolute contraindication: assess for serotonin syndrome risk and refer if the patient is symptomatic or uncertain. Triptans are not licensed for patients over 65.3 Prochlorperazine buccal (Buccastem) is available over the counter for migraine-associated nausea. Migraine management is not a clinical pathway condition under NHS Pharmacy First in England. Warn patients using triptans or combination analgesics on more than 10 days per month, or simple analgesics on more than 15 days per month, about medication overuse headache.3 Safety-net: seek urgent help if the headache changes character, becomes the worst the patient has ever had, or is accompanied by fever, neck stiffness, visual change, rash, or any neurological symptoms.
Key takeaways
- A thunderclap headache reaching maximum intensity within 5 minutes and described as the worst ever is subarachnoid haemorrhage until proven otherwise: call 999, advise against driving or self-transfer, and do not let analgesia delay activation.
- New acute visual symptoms at any age require same-day urgent assessment; in patients over 50 with temporal headache and visual loss, treat as a same-day emergency for giant cell arteritis as irreversible sight loss can occur within hours.
- Before supplying OTC sumatriptan, confirm a pre-existing migraine diagnosis, age 18 to 65, no cardiovascular risk factors, no pregnancy, no MAOIs or ergots, and assess serotonin syndrome risk if SSRIs or SNRIs are present; triptans are not licensed over age 65.
📚 References
- National Institute for Health and Care Excellence. Headache: assessment. NICE Clinical Knowledge Summary. London: NICE; 2024. Available from: https://cks.nice.org.uk/topics/headache-assessment/
- National Institute for Health and Care Excellence. Headaches in over 12s: diagnosis and management. NICE guideline CG150. London: NICE; 2012 (updated 2021). Available from: https://www.nice.org.uk/guidance/cg150
- National Institute for Health and Care Excellence. Migraine. NICE Clinical Knowledge Summary. London: NICE; 2023. Available from: https://cks.nice.org.uk/topics/migraine/
- National Institute for Health and Care Excellence. Giant cell arteritis. NICE Clinical Knowledge Summary. London: NICE; 2023. Available from: https://cks.nice.org.uk/topics/giant-cell-arteritis/
- National Institute for Health and Care Excellence. Meningitis: bacterial meningitis and meningococcal disease. NICE Clinical Knowledge Summary. London: NICE; 2023. Available from: https://cks.nice.org.uk/topics/meningitis-bacterial-meningitis-meningococcal-disease/