What is anaphylaxis?

Anaphylaxis is potentially life-threatening, and always requires an immediate emergency response. If you or your child have had anaphylaxis, this page will help you understand more about it: what anaphylaxis is, what increases the risk of anaphylaxis, the treatment and where to get further information.

If you have experienced an allergic reaction in the past, you may be at risk of anaphylaxis even if you have not had anaphylaxis before. We advise that you see your GP – they can refer you to an allergy clinic if needed.

What are the symptoms of anaphylaxis?

Most healthcare professionals consider an allergic reaction to be anaphylaxis when it involves difficulty in breathing or affects the heart rhythm or blood pressure.

In extreme cases there could be a dramatic fall in blood pressure. The person may become weak and floppy and may have a sense of something terrible happening. Any of the ABC symptoms may lead to collapse and unconsciousness and, on rare occasions, can be fatal.


Any one or more of the following symptoms may be present – these are often referred to as the ABC symptoms.
  • right_arrow_orange_icon AIRWAY -swelling in the throat, tongue or upper airways (tightening of the throat, hoarse voice, difficulty swallowing)
  • right_arrow_orange_icon BREATHING - sudden onset wheezing, breathing difficulty, noisy breathing
  • right_arrow_orange_icon CIRCULATION - dizziness, feeling faint, sudden sleepiness, tiredness, confusion, pale clammy skin, loss of consciousness

Additional Symptoms

Other symptoms that might be present include:

  • a red raised rash (known as hives or urticaria) anywhere on the body
  • a tingling or itchy feeling in the mouth
  • swelling of lips, face or eyes
  • stomach pain or vomiting.


These symptoms can also happen on their own. If you don’t have the ABC symptoms, the reaction is likely to be less serious and is not the same as anaphylaxis, but watch carefully in case ABC symptoms develop.

To be prepared and to help you and those around you know what to do in an emergency, it’s important to have an allergy action plan.

What increases the risk of a serious allergic reaction?

There are times when you may be particularly vulnerable and at increased risk of a serious reaction. Times when you need to be particularly careful to avoid the culprit allergen include:

If you have asthma that is poorly controlled

If you are suffering from an infection, or have recently had one

If you exercise just before or just after contact with the allergen

If you are also suffering from hay fever

During times of emotional stress

If you have been drinking alcohol

If you have taken a ‘non-steroid anti-inflammatory drug’ (NSAID) such as aspirin or ibuprofen

What is the treatment for a serious allergic reaction?

Pre-loaded auto-injectors containing adrenaline are prescribed for people who are at risk of anaphylaxis. Adrenaline is referred to in some countries as epinephrine, which is the internationally recognised term for adrenaline.

Because serious allergic reactions can occur very quickly, adrenaline auto-injectors must always be readily available. It is important to carry two adrenaline auto-injectors at all times which are in date and of the correct dose.

Further Information

  • I suspect I have an allergy, what should I do?

    If you suspect you have an allergy, see your GP as soon as possible. Many GPs are well informed about allergies and can make a diagnosis to decide whether you need adrenaline or not. In many cases, the GP will need to refer you to an NHS allergy clinic.

  • I suspect I am at risk of having anaphylaxis

    If you’re at risk of having anaphylaxis, you’re likely to be prescribed adrenaline. This must be available at all times.

  • I have asthma as well as allergies

    If you have asthma as well as allergies, make sure your asthma is well managed. If you have poorly controlled asthma, there is a higher likelihood of any allergic reaction becoming severe. See your GP or asthma nurse for advice on this crucial point and to obtain an asthma management plan to help you self-manage.