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Anaphylaxis is a severe, potentially life-threatening allergic reaction that can develop rapidly.
It is also known as anaphylactic shock.
Signs of anaphylaxis include:
- breathing difficulties
- feeling light-headed or faint
- changes to your skin such as itchy skin or a raised red skin rash
- swelling of certain body parts, particularly the face (angioedema)
Read more about the symptoms of anaphylaxis.
What to do
Anaphylaxis should always be treated as a medical emergency.
If you suspect that you or somebody else is experiencing symptoms of anaphylaxis you should immediately dial 999 for an ambulance.
If available, an injection of a medicine called adrenaline should be given if someone is having breathing difficulties, is feeling faint or has lost consciousness due to suspected anaphylaxis.
Some people with a previous history of anaphylaxis will have an auto-injector of adrenaline. This should be injected into their thigh muscle and held in place for 10 seconds. Instructions for how to use these auto-injectors can be found on the side of each device.
If the person is conscious, you should place them in a position where they are comfortable and able to breathe easily until the ambulance arrives. If they are feeling faint, they should be laid flat with their legs elevated if possible.
If the person is unconscious, you should place them in the recovery position (on their side, supported by one leg and one arm, with the head tilted back and the chin lifted).
If the person's breathing or heart stops, cardiopulmonary resuscitation (CPR) should be performed.
Further treatment and observation will be carried out in hospital.
Read more about treating anaphylaxis.
Causes and triggers
Anaphylaxis is the result of your body's immune system overreacting to a harmless substance, such as food. Substances that provoke allergic reactions are known as allergens.
Anaphylaxis usually develops within minutes of contact with an allergen, though sometimes the reaction can happen hours later.
The most widely reported triggers of anaphylaxis are:
- insect stings; particularly wasp and bee stings
- other types of foods such as milk and seafood
- certain medications such as some types of antibiotics
Read more about the causes of anaphylaxis.
Preventing further episodes
If you know what has triggered anaphylaxis, it is important to take steps to try to avoid further exposure to similar triggers.
If the cause of the allergic reaction is not known, you should be referred to a specialist allergy clinic where tests can be carried out to help identify possible triggers.
You may be provided with an adrenaline auto-injector to use during any future episodes of anaphylaxis.
Read more about preventing anaphylaxis.