Severe allergic reaction (anaphylaxis): learn first aid

Adult first aid for someone suffering a severe allergic reaction, including signs and symptoms to look out for and the steps to take in an emergency.

What is anaphylaxis?

Anaphylaxis (also called anaphylactic shock) is a severe allergic reaction that makes it difficult for a person to breathe.

Anaphylactic shock develops within seconds or minutes of contact with a “trigger” and is an emergency. Common causes of allergic reactions are pollen, stings and bites, latex and some food items, such as nuts, shellfish, eggs or dairy products.

If a doctor identifies someone as being at risk of anaphylactic shock, they may give them an auto-injector. An auto-injector contains medication that helps to ease the symptoms in an emergency.

Signs and symptoms of anaphylactic shock

Mild allergies typically cause itchy skin and eyes, while severe allergies can also result in symptoms like swelling of the tongue or neck and difficulty breathing.

The person will have had contact with something they are severely allergic to, though it may not be clear what this was. They may have difficulty breathing, flushed or paler skin and a visibly swollen tongue or throat. They might be confused or feel very scared.

First aid steps for a severe allergic reaction (anaphylaxis)

1. Call 999

2. If they have medication, help them to use it.

Follow the instructions on the packaging. If you are trained how to use an autoinjector you can give it to them yourself. 

3. If they have a known allergy, use their auto-injector.

If someone has a known allergy, they may have been prescribed an auto-injector. Follow the guidance on the packaging.

Watch Amy's video to learn first aid for severe allergic reactions

Meet Amy, someone who has a severe nut allergy and has experienced anaphylactic shock. Learn how Amy applied basic first aid during an anaphylaxis emergency. Skip to 0:55 seconds for the key first aid steps.

Frequently asked questions about severe allergic reactions (anaphylaxis)

Should I use their auto-injector for them?

If the person has an auto-injector, you can help them use it or do it yourself, following the guidance on the injector.


How do I use an auto-injector?

The auto-injector will have instructions on the side of its packaging which you should follow. Give the auto-injector you used to the ambulance crew when they arrive.


Can I use an auto-injector on a child with a known allergy if they have a severe allergic reaction?

Yes. If the child has an auto-injector, you can give them an auto-injection following the guidance on the packaging.


What should I do if the person becomes unresponsive and stops breathing?

Find out:


How can I get an insect sting out of someone’s skin?

If the sting is still in the skin, brush or scrape it off sideways with your fingernail or a credit card. After the sting has been removed, apply something cold to the area (such as an ice pack) to minimise the pain and swelling. Be aware that this may not reduce the risk of an allergic reaction for someone with a severe allergy.


Where can I find more information about allergic reaction first aid?

If you have any other questions about first aid for someone who is having a severe allergic reaction, visit the NHS website. During life-threatening emergencies, call 999, or for non-emergency medical help, call 111.

To test your knowledge about first aid for anaphylactic shock, try our First aid app quiz.