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What to do if…
you have a sudden, severe, and unusual headache

Produced and maintained by PanicStation.org Published: Last reviewed: Editorial policy UK guide

Short answer

Treat a sudden, severe, unusual headache as urgent. If it came on suddenly and is extremely painful, especially if it feels like the worst headache you have had, call 999 now, or 112 if needed, and do not drive yourself.

Do not do these things

  • Do not wait it out if the headache came on suddenly and is extremely painful.
  • Do not drive yourself to A&E if you feel faint, confused, drowsy, weak, 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 try to sleep through it.
  • Do not stay alone if you feel seriously unwell or your symptoms are changing.

What to do now

  1. Get to a safer pause and reduce the risk of falling. Sit or lie down somewhere safe, loosen tight clothing, and ask someone to stay with you if possible.
  2. Call 999 now, or 112 if needed, if any of these apply:
    • The headache started suddenly and is extremely painful, like a thunderclap or blinding pain.
    • The sudden severe headache started during or just after exertion or sex.
    • You have new stroke-like symptoms, such as face drooping, arm or leg weakness, numbness on one side, speech trouble, sudden vision loss, or new trouble walking or balancing.
    • You are very drowsy, confused, fainted, had a seizure, or are hard to rouse.
    • The headache followed a significant head injury.
    • You have a severe headache with fever and a stiff neck, a new rash, or signs of being seriously unwell.
    • You have a severe headache with a red or painful eye, or a sudden major vision change.
  3. If the headache is severe and unusual but not clearly in the 999 list above, call NHS 111 for urgent advice and help arranging assessment today. In Scotland, 111 is provided by NHS 24.
  4. When you speak to 999, 111, A&E, or a clinician, say the key details clearly:
    • The exact time the headache started and how fast it reached its worst point.
    • What you were doing when it started.
    • Any new weakness, numbness, confusion, speech change, vision change, neck stiffness, fever, vomiting, fainting, or seizure.
    • Whether you are pregnant, within 6 weeks after giving birth, have had a recent head or neck injury, or have had a recent infection.
    • Any blood thinners, such as warfarin, apixaban, rivaroxaban, edoxaban or dabigatran, and any new medicines or recreational drugs.
  5. If you are pregnant or recently postpartum and you have a home blood pressure monitor, take a reading only if you can do it safely and without delaying help. Tell 999, 111, or the clinician the reading.
  6. While waiting for help:
    • Keep your phone close and unlocked if you can.
    • If you are alone and it is safe to do so, unlock the door or make it easier for help to reach you.
    • Gather ID and a list or photo of your medicines and allergies.
    • If you might vomit, lie on your side.
    • Avoid alcohol and sedatives.

What can wait

  • Trying to work out the cause.
  • Searching symptoms online.
  • Deciding whether you “really” deserve urgent care.
  • Finishing work, driving home, tidying up, or updating people who do not need to know right now.

Important reassurance

Many headaches are not caused by something dangerous. A sudden, severe, unusual headache is still worth treating as urgent because some serious causes are time-sensitive and hard to rule out at home.

Scope note

These are first steps to help you stay safer and get the right urgent assessment. Later decisions about tests, treatment, and follow-up may need a clinician or another specialist.

Important note

This is general information, not medical advice or a diagnosis. If you think you may be having an emergency, call 999 now, or 112 if needed.

Additional Resources

Closely connected guides that may be useful during the same situation or its immediate aftermath.

About this guide

This guide was produced and is maintained by PanicStation.org using its published editorial process. Official and specialist sources are checked where relevant, and AI-assisted tools may be used for drafting, organisation, and consistency checks. The site operator remains responsible for publication, revision, and removal decisions.

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