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uk Health & medical scares sudden severe headache • unusual headache for you • thunderclap headache • worst headache of life • headache came on suddenly • very severe head pain • sudden headache and nausea • sudden headache and vomiting • headache with weakness • headache with slurred speech • headache with vision changes • headache with confusion • headache after head injury • headache with stiff neck • headache with fever • new neurological symptoms • sudden one-sided weakness • face droop headache • severe headache pregnant • postpartum severe headache • severe headache on blood thinners

What to do if…
you have a sudden severe headache that is unusual for you

Short answer

Treat a sudden, severe, unusual headache as urgent. If it came on suddenly and is very severe (especially “worst ever”), call 999 (or 112) now and do not drive yourself.

Do not do these things

  • Do not “wait it out” if it’s sudden and very severe, or if you have any new neurological symptoms (weakness, speech/vision problems, confusion).
  • Do not drive yourself to A&E if you feel faint, confused, drowsy, or your vision is affected.
  • Do not take extra doses of painkillers beyond the label (including mixing products that both contain paracetamol).
  • Do not drink alcohol or take sedatives to “knock yourself out”.
  • Do not stay alone if you feel significantly unwell or your symptoms are changing.

What to do now

  1. Get to a safer pause and reduce risk of falling. Sit or lie down somewhere safe, loosen tight clothing, and ask someone to stay with you if possible.
  2. Decide “999/112 now” vs “urgent same-day help”:
    • Call 999 (or 112) now if any of these apply:
      • Headache started suddenly and is extremely severe (a “thunderclap”/blinding pain).
      • The severe headache started during/just after exertion or sex.
      • New stroke-like symptoms: face droop, arm/leg weakness, speech trouble, sudden vision loss, new trouble walking/balance.
      • You’re very drowsy, confused, fainted, had a seizure, or are hard to rouse.
      • Headache after a significant head injury.
      • Severe headache with fever and stiff neck, a new rash, or signs of being seriously unwell.
      • Severe headache with a red/painful eye or sudden major vision change.
    • If it’s severe and unusual but not clearly in the emergency list above, contact NHS 111 (NHS 24 in Scotland) for urgent advice and help arranging assessment as soon as possible today.
  3. If you call 999/112 or attend A&E, say the key details clearly:
    • The exact time it started, how fast it peaked (seconds/minutes vs gradual), and what you were doing.
    • Any new symptoms (weakness, numbness, confusion, speech/vision change, neck stiffness, fever, vomiting).
    • Any pregnancy or within 6 weeks after birth, recent infection, recent head/neck injury, or unusual exertion.
    • Medicines that matter urgently: blood thinners (e.g., warfarin/DOACs), steroids, or new medications/recreational drugs.
  4. If pregnant or recently postpartum and you have a home blood pressure monitor: take a reading (if you can do so safely) and share the number with 999/112, 111, or the clinician. Do not delay calling for help to do this.
  5. While waiting for help:
    • Keep your phone unlocked and close. If you’re alone, consider unlocking the front door and keeping a key accessible.
    • Gather ID and a list/photo of medications and allergies.
    • If you might vomit, lie on your side.
    • Avoid alcohol and sedatives. Small sips of water are usually OK unless you’re very drowsy, actively vomiting, or you’ve been told not to drink.

What can wait

  • Trying to work out the cause, searching symptoms, or asking others for reassurance online.
  • Deciding whether you “really” deserve urgent care.
  • Non-urgent tasks like finishing work, driving home, or tidying up.

Important reassurance

A lot of headaches turn out not to be dangerous. But a sudden, severe, unusual headache is one of the situations where getting checked quickly is the safer choice—because the serious causes are time-sensitive and easy to miss at home.

Scope note

These are first steps to keep you safe and get the right level of urgent assessment. Further decisions (tests, treatment, follow-up) can be made once you’ve been properly evaluated.

Important note

This is general information, not a diagnosis. If you think you may be having an emergency, call 999 (or 112) immediately.

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