Anaphylaxis

Anaphylaxis is a severe type of allergic reaction. Your body has reacted to a protein (called an allergen) that it shouldn’t be sensitive to.

Anaphylaxis can be caused by things like:

  • food including nuts and shellfish
  • wasp or bee stings
  • certain medicines such as antibiotics.

Sometimes we do not know what has triggered the episode of anaphylaxis.

We think that you have had an episode of anaphylaxis but are now well enough to go home.

What should I do when I get home?

Some people’s symptoms return in the hours after they have been discharged from hospital. If you start to feel unwell again you should return to the Emergency Department.

What can I do to stop it happening again?

You should make an appointment with your GP so that they can arrange follow up if you need it.

You must avoid contact with whatever has caused the episode of anaphylaxis. This may mean that you have to look at the ingredients list on food in shops and when eating out or getting a take away.

How can I tell if I am having another anaphylaxis attack?

The following symptoms may mean that an allergic reaction is anaphylaxis:

  • difficulty breathing or noisy breathing
  • wheezing
  • tongue swelling
  • a tight throat
  • problems talking or a hoarse voice
  • collasping

A young child with anaphylaxis may look pale and floppy.

What should I do if I think I have anaphylaxis?

We should have given you two adrenaline injectors. You should use these if you think you are having an anaphylaxis attack. Use one injector and call 999, telling the operator that you are having an anaphylaxis attack.

You can use your second injector if your symptoms have not improved after five minutes. Make sure you inject yourself in a different place from the first injection.

How should I use my injector?

You will have been given an EpiPen injector. Follow the instructions in the pictures to give yourself the medicine. You do not need to take off your trousers including jeans to inject yourself. Watch a video on YouTube from King's College Hospital London: How to use your EpiPen.

What if I can’t give the injector myself?

Sometimes people who are having anaphylaxis are too ill to inject themselves. A friend or family member can do it for you. It is important that you teach them how to do this before you are in the situation where you need them to. You can order training EpiPens from the EpiPen website.

What else should I do?

Register on the EpiPen website to get reminders of when your EpiPen is going to expire. An out of date EpiPen may be useless if you develop anaphylaxis.

Where else can I get information and support?

Anaphylaxis can be very scary when it happens. Some people find the changes to their life after an episode difficult. You can contact your GP if you want to discuss things. The websites below may also be helpful:

Reviewed by Dr Thomas Shaw in September 2023, next review in September 2026.

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  • Page last reviewed: 24 April 2024
  • Next review due: 16 August 2026