Treating someone who has anaphylaxis 

If you think that somebody is experiencing symptoms of anaphylaxis, you should use an adrenaline injector if one is available. Dial 999 immediately if an adrenaline injector is not available.

If you can see a potential trigger, such as a wasp or bee sting stuck in their skin, carefully remove it.

Adrenaline injections

Adrenaline causes the blood vessels to become narrower, which raises your blood pressure and reduces swelling. It also causes the airways to open, relieving breathing difficulties.

An adrenaline injection should be given as soon as a serious reaction is suspected.

Signs of suspected anaphylaxis:

  • problems breathing
  • feeling faint or dizzy
  • loss of consciousness

This can be done by the person with anaphylaxis, but sometimes (if it’s a young child or someone who is unconscious) another person may need to give the injection.

Before attempting the injection, make sure you know what to do. You should read all of the instructions carefully when you, or the person you are responsible for, are first prescribed the injector.

After injecting, the syringe should be held in place for 5-10 seconds. Injections can be given through clothing.

After injecting the adrenaline, you should immediately dial 999 for an ambulance, even if the person is starting to feel better.

Most people should experience a rapid improvement in symptoms once the adrenaline has been used. If there’s no improvement after 5-10 minutes, you should inject a second dose of adrenaline, if one is available. This should be injected into the opposite thigh.

Read MHRA (2014) guidelines on how to use an adrenaline auto-injector (PDF, 188kb).

Positioning and resuscitation

In most cases, the person should lie flat with their legs raised on a chair or a low table, to help maintain blood flow to the head and heart.

Pregnant women should lie down on their left side to avoid putting too much pressure on the large vein that leads to the heart.

If the person is conscious but having trouble breathing, they should sit up to make breathing easier.

If the person is unconscious, check that their airways are open and clear, and also check their breathing. Then put them in the recovery position (see below) to make sure they don’t choke on their vomit.

Place the person on their side, making sure they are supported by one leg and one arm. Open the airway by tilting the head and lifting the chin.

If the person's breathing or heart stops, cardiopulmonary resuscitation (CPR) should be performed.

Admission to hospital

Even if adrenaline is given, the person will need to go to hospital for observation (usually for 6 to 12 hours) as symptoms can occasionally return during this period.

While in hospital, an oxygen mask can be used to help breathing, and fluids given by an intravenous drip (directly into a vein) can help to increase blood pressure.

As well as adrenaline, additional medications such as antihistamines and corticosteroids can be used to help relieve symptoms.

Blood tests may also be carried out while you’re in hospital to confirm anaphylaxis.

You should be able to leave hospital when the symptoms are under control and it’s thought that they will not quickly return. This may be after a few hours, but you may have to stay in hospital for a few days if the symptoms were severe.

You may be asked to take antihistamines and corticosteroid tablets two to three days after leaving hospital, to help stop your symptoms returning.

You will probably be asked to attend a follow-up appointment, so you can be given advice about how you can avoid further episodes of anaphylaxis. An adrenaline auto-injector may be given to you for emergency use between leaving hospital and attending the follow-up appointment.

Read more about preventing anaphylaxis.

Page last reviewed: 04/12/2014

Next review due: 04/12/2016