Anaphylaxis

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

It's also known as anaphylactic shock.

This page covers:

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.

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

If someone has symptoms of anaphylaxis, you should:

call 999 for an ambulance immediately – mention that you think the person has anaphylaxis
remove any trigger if possible – for example, carefully remove any wasp or bee sting stuck in the skin
lie the person down flat – unless they're unconscious, pregnant or having breathing difficulties
use an adrenaline auto-injector if the person has one – but make sure you know how to use it correctly first
give another injection after 5-15 minutes if the symptoms don't 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.

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

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 isn't always.

Common anaphylaxis triggers include:

foods – including nuts, milk, fish, shellfish, eggs and some fruits
medicines – including some antibiotics and non-steroidal anti-inflammatory drugs (NSAIDs) such as aspirin
insect stings – particularly wasp and bee stings
general anaesthetic
contrast agents – special dyes used in some medical tests to help certain areas of your body show up better on scans
latex – a type of rubber found in some rubber gloves and condoms

In some cases, there's no obvious trigger. This is known as idiopathic 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 – give yourself an injection whenever you think you may be experiencing anaphylaxis, even if you're not completely sure