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What to do if…
you develop hives, facial swelling, throat tightness, or hoarseness after a possible allergen

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

Short answer

Call 999 now if your throat feels tight, your voice becomes hoarse, your lips, mouth, tongue, or throat suddenly swell, or you develop breathing difficulty, confusion, dizziness, or faintness. Use your prescribed adrenaline auto-injector immediately if you have one, then say that you may be having an anaphylactic reaction.

Do not do these things

  • Do not wait for throat, voice, breathing, or mouth swelling symptoms to settle by themselves.
  • Do not stand, walk around, or drive yourself to hospital.
  • Do not delay an adrenaline auto-injector or the 999 call while looking for antihistamines.
  • Do not eat or drink if swallowing feels difficult.
  • Do not stay alone while waiting for emergency help.
  • Do not deliberately expose yourself to the suspected allergen again.

What to do now

  1. Use your prescribed adrenaline auto-injector without delay if you have one and you suspect anaphylaxis. Follow the instructions on your particular device.
  2. Call 999 for an ambulance immediately after using the injector, or straight away if you do not have one. Say “anaphylaxis” and describe the throat tightness, hoarseness, swelling, breathing changes, hives, dizziness, or other symptoms.
  3. Lie down and raise your legs. If breathing is difficult, raise your shoulders or sit up slowly without standing. If you are pregnant, lie on your left side.
  4. Stay lying down and do not stand or walk, even if you begin to feel better.
  5. Ask someone to stay with you, unlock the door if safe, and bring your second auto-injector and any packaging connected with the possible allergen.
  6. If your symptoms have not improved after five minutes, use your second prescribed adrenaline auto-injector if you have one.
  7. If an insect sting remains in your skin, try to remove it without delaying adrenaline or the ambulance call.
  8. If you have only hives or swelling away from your lips, mouth, tongue, or throat and otherwise feel well, avoid the suspected trigger and seek prompt advice from NHS 111. Call 999 immediately if throat, breathing, swallowing, consciousness, or mouth swelling symptoms appear.
  9. If you become unresponsive or stop breathing normally, anyone with you should follow the 999 call handler’s instructions and begin CPR.

What can wait

Identifying the exact allergen, arranging tests, changing your diet or regular medicines, replacing used injectors, and planning how to prevent another reaction can wait. Deal first with adrenaline if prescribed, emergency help, safe positioning, and having someone stay with you.

Important reassurance

You do not need to be certain that the reaction is anaphylaxis before calling 999 or using a prescribed adrenaline auto-injector when serious symptoms are present. Throat tightness, hoarseness, sudden mouth or throat swelling, and breathing difficulty are appropriate reasons to seek emergency help.

Scope note

This guide covers only the first actions during a possible serious allergic reaction. Later assessment of the cause and future emergency planning may require hospital staff, your GP, or an allergy specialist.

Important note

This is general health information and is not a diagnosis or a substitute for emergency medical assessment. Follow the instructions from the 999 call handler, ambulance clinicians, and your own prescribed adrenaline auto-injector.

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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