Anaphylaxis

Anaphylaxis is a severe and potentially life-threatening reaction to a trigger such as an allergy.


Symptoms of anaphylaxis

Anaphylaxis usually develops suddenly and gets worse very quickly.

The symptoms include:

There may also be other allergy symptoms, including an itchy, raised rash (hives), feeling or being sick, swelling (angioedema), or stomach pain.

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What to do if someone has anaphylaxis

Anaphylaxis is a medical emergency. It can be very serious if not treated quickly.

If someone has symptoms of anaphylaxis, you should:

  1. Use an adrenaline auto-injector if the person has one – but make sure you know how to use it correctly first.
  2. Call 999 for an ambulance immediately (even if they start to feel better) – mention that you think the person has anaphylaxis.
  3. Remove any trigger if possible – for example, carefully remove any stinger stuck in the skin.
  4. Lie the person down flat – unless they're unconscious, pregnant or having breathing difficulties.
  5. Give another injection after 5 to 15 minutes if the symptoms do not improve and a second auto-injector is available.

If you're having an anaphylactic reaction, you can follow these steps yourself if you feel able to.

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Read about how to treat anaphylaxis for more advice about using auto-injectors and correct positioning.

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Triggers of anaphylaxis

Anaphylaxis is the result of the immune system, the body's natural defence system, overreacting to a trigger.

This is often something you're allergic to, but not always.

Common anaphylaxis triggers include:

In some cases, there's no obvious trigger. This is known as idiopathic anaphylaxis.

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Preventing anaphylaxis

If you have a serious allergy or have experienced anaphylaxis before, it's important to try to prevent future episodes.

The following can help reduce your risk:

  • identify any triggers – you may be referred to an allergy clinic for allergy tests to check for anything that could trigger anaphylaxis
  • avoid triggers whenever possible – for example, you should be careful when food shopping or eating out if you have a food allergy
  • carry your adrenaline auto-injector at all times (if you have 2, carry them both) – give yourself an injection whenever you think you may be experiencing anaphylaxis, even if you're not completely sure

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