What are the symptoms of anaphylaxis?

A reaction is usually classed as anaphylaxis if there are changes in a person’s breathing, heart rate or blood pressure. Most healthcare professionals consider an allergic reaction to be anaphylaxis when it involves a difficulty in breathing or affects the heart rhythm or blood pressure.


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 - persistent cough, vocal changes (hoarse voice), difficulty in swallowing, swollen tongue
  • right_arrow_orange_icon BREATHING - difficult or noisy breathing, wheezing (like an asthma attack)
  • right_arrow_orange_icon CIRCULATION - feeling light-headed or faint, clammy skin, confusion, weak, floppy, unresponsive or unconscious (because of a drop in blood pressure)

Additional Symptoms

The ABC symptoms will usually (but not always) also come with other less-serious symptoms:

  • Widespread flushing of the skin.
  • Rash.
  • Swelling of the skin anywhere on the body (for example, lips, face).
  • Stomach pain, feeling sick and vomiting.

If the person doesn’t have any of the key ABC symptoms, the allergic reaction is probably less serious. But even then, you should 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 severe reaction?

There are times when you may be particularly vulnerable and at increased risk of a severe 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 severe reaction?

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

Because severe allergic reactions can occur rapidly, the prescribed auto-injectors must be readily available at all times. In our view, it is important to ensure that you carry two adrenaline auto-injectors at all times which are in date and of the correct dose.

  • right_arrow_orange_icon The injection should be given as soon as any symptoms of anaphylaxis are present. If in doubt, give adrenaline
  • right_arrow_orange_icon A second dose should be given after 5-10 minutes if symptoms of anaphylaxis remain, or if there is any doubt about whether the symptoms have improved
  • right_arrow_orange_icon An ambulance must be called immediately following an injection of adrenaline, even if there is immediate improvement
  • right_arrow_orange_icon The emergency service operator must be told the person is suffering from anaphylaxis and needs to be attended by paramedics

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 allergy 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 the severe form of allergy, anaphylaxis

    If you are at risk of the severe form of allergy – anaphylaxis – you are 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.