Clinical cases
Headache: when to worry — a case-based approach to red flags
This is an illustrative educational case, not a real patient. Headache is extremely common and almost always benign, which is exactly why the dangerous minority must be actively looked for. The clinical skill lies in recognising "red flag" features that separate a primary headache (like migraine or tension-type) from a serious secondary cause. We use a fictional case to show how that filtering works.
Education and reference only. This article explains how treatments work in plain language — it contains no doses and is not a substitute for advice from your doctor or pharmacist. Always discuss your own treatment with a qualified clinician.
The presentation
A 45-year-old man describes a sudden, severe headache that reached maximum intensity within seconds while he was lifting something heavy — "like being hit on the back of the head" — now with neck stiffness and vomiting. Almost everything here is a warning sign. A "thunderclap" headache that peaks instantly is the classic presentation of subarachnoid haemorrhage (bleeding around the brain) until proven otherwise, and it demands emergency assessment.
The red flags that change everything
Certain features shift a headache from routine to urgent. Widely used red flags include: a thunderclap onset (maximal within seconds to a minute); a new headache in someone over 50; headache with fever and neck stiffness (meningitis); progressive headache worse in the morning or on coughing, straining or lying down (raised intracranial pressure); headache with new neurological signs, seizures or personality change; headache after head injury; and new headache in someone with cancer or a weakened immune system. The presence of any of these prompts urgent evaluation and usually imaging.
The common, benign causes
Most headaches are primary. Tension-type headache is a common, bilateral, pressing "band around the head" without the features above. Migraine is typically a moderate-to-severe, often one-sided, throbbing headache lasting hours to a few days, frequently with nausea, light and sound sensitivity, and sometimes a preceding visual "aura". Cluster headache causes severe, strictly one-sided pain around the eye with tearing and a blocked nostril, in bouts. Recognising these patterns confidently is what allows a clinician to reassure and treat without unnecessary scans — but only after red flags are excluded.
What the case needs
In this case the thunderclap onset with neck stiffness and vomiting mandates emergency assessment for subarachnoid haemorrhage: urgent CT of the head, and if that is normal but suspicion remains, a lumbar puncture after a delay to look for blood breakdown products. This is a situation where a "normal-looking" patient can be harbouring a catastrophic bleed, and where acting on the pattern rather than waiting is what saves lives.
What the case teaches
The lesson is a safe filter: for every headache, actively screen for red flags first; if none are present and the pattern fits a recognised primary headache, treat and safety-net; if any red flag is present, investigate urgently. Most people with headache need reassurance and simple management, but the discipline of always checking for the dangerous features is what makes that reassurance safe.
In short
Key takeaways
- Most headaches are benign primary headaches (tension-type, migraine, cluster), but serious secondary causes must be actively excluded.
- A thunderclap headache reaching peak intensity within seconds is a subarachnoid haemorrhage until proven otherwise — a medical emergency.
- Key red flags include new headache over 50, fever with neck stiffness, progressive headache worse on straining, new neurological signs, and headache after injury.
- Recognising typical primary-headache patterns allows safe reassurance once red flags are excluded.
- Educational illustration only — a sudden severe or "worst ever" headache needs emergency assessment.
Answers
Frequently asked questions
Is this based on a real person?
No — it is a fictional teaching case for education, not advice for any individual.
When should a headache be treated as an emergency?
A sudden "worst ever" or thunderclap headache, headache with fever and a stiff neck, headache with weakness, confusion, seizures or vision loss, or headache after a head injury all need emergency assessment — call 999 or go to A&E.
How can I tell a migraine from something serious?
Migraine tends to follow a recognisable pattern over time (often one-sided, throbbing, with nausea and light sensitivity). A new, sudden, or rapidly changing headache — especially with the red flags above — should be assessed by a clinician rather than assumed to be migraine.
Go deeper
Related guides
Sources
Where this is drawn from
- NICE CG150 — Headaches in over 12s: diagnosis and management
- NICE CKS — Headache assessment
- SIGN 155 — Pharmacological management of migraine
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