What is anaphylaxis?

Anaphylaxis (pronounced ana-fill-ax-is) is a severe and potentially life-threatening allergic reaction affecting more than one body system such as the airways, heart, circulation, gut and skin. 

Symptoms can start within seconds or minutes of exposure to the food or substance you are allergic to and usually will progress rapidly. On rare occasions there may be a delay in the onset of a few hours.

Advice for children about anaphylaxis

Certain food and non-food items can make some children sick. This is because some children have allergies.

Most of the time, you find out if you have an allergy when you are very young but sometimes you notice it when you try something for the first time.

If you have an allergy then your doctor, parent or another adult will talk to you about food that may not be ‘safe’ for you to eat.

If you do not have any allergies but feel funny after eating something then do talk to your teacher or an adult you trust about it, especially if you feel very unwell. 

You may notice any of these symptoms:

  • Feeling weak 
  • Widespread flushing of the skin
  • Nettle rash (otherwise known as hives)
  • Swelling of the skin anywhere on the body
  • Swelling of the lips
  • Abdominal pain, nausea and vomiting.

If you feel like this at any time talk to your teacher, parent or another adult that you trust

If you know you have anaphylaxis already then you will have medicine to help you if you feel unwell. You may have a medical card that explains your allergies too so do show this to others including your teachers so they know about your allergies and can tell other people too.

  • If your child needs one, make sure that they have an in date Epipen on them and a spare Epipen is kept in the medical room at the school they attend
  • Make sure that the school staff are aware that your child is at risk of an anaphylactic reaction to certain triggers and discuss a care plan with the school and school nurse to make sure that the correct procedure is followed to maintain health while at school
  • Make sure that the medication your child may be required to take or needs to be administered in school in an emergency is in date and available at all times. This includes inhalers if they are also asthmatic as this may be required at the same time as giving adrenaline

The common causes of anaphylaxis include foods such as, peanuts, tree nuts, milk, eggs, shellfish, fish, sesame seeds and kiwi fruit, although many other foods have been known to trigger anaphylaxis.

Non-food causes include wasp or bee stings, natural latex (rubber), and certain drugs such as penicillin.

In some people exercise can trigger a severe reaction – either on its own or in combination with other factors such as food or drugs, for example, aspirin.

You may notice any of the following severe symptoms.

There may also be a dramatic fall in blood pressure (anaphylactic shock). The person may become weak and floppy and may have a sense of something terrible happening. This may lead to collapse, unconsciousness and – on rare occasions – death.

In addition to those severe symptoms listed above, there may also be:

  • Widespread flushing of the skin
  • Nettle rash (otherwise known as hives or urticaria)
  • Swelling of the skin (known as angioedema) anywhere on the body.
  • Swelling of the lips
  • Abdominal pain, nausea and vomiting.

These symptoms can also occur on their own, without the more severe ones. Where that is the case, the reaction is likely to be less serious but you should watch carefully in case any of the more severe ones develop.


These come on quickly and symptoms get rapidly worse, but once treated, the symptoms go and don’t return.


These are reactions which may be mild or severe to start with, followed by a period of time when there are no symptoms, and then increasing symptoms with breathing and blood-pressure problems.

If you have an anaphylactic reaction, you will need an observation period in hospital after you have recovered in case you experience a biphasic reaction.

Most biphasic reactions occur within hours of the initial reaction but, rarely, they can be more delayed (Lee et al, 2015).  On very rare occasions, a biphasic reaction has been known to occur as long as 72 hours after the initial reaction.

The length of the observation period would be for your treating doctor to decide. The National Institute for Health and Care Excellence (NICE) recommends that people who have had a severe allergic reaction should be monitored for six to 12 hours within a hospital setting because of the risk of a bi-phasic reaction. Children are likely to be admitted to hospital at least overnight (NICE 2011).

Protracted anaphylaxis

This can last for several days and may need treatment in hospital for some time.

Pre-loaded auto-injectors (sometimes referred to as ‘pens’ or Epipens) 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.

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 aeroallergen symptoms, such as hay fever
  • During times of emotional stress
  • If you have been drinking alcohol.

If someone is having a severe allergic reaction, it is vital that they receive an adrenaline injection. If they have their own adrenaline, this must be given as soon as a severe reaction is suspected to be occurring and an ambulance must be called immediately. If the patient is alone or is unable to self-administer, the adrenaline should be administered first then an ambulance should be called immediately after.

  • Try to make sure that a person suffering an allergic reaction remains as still as possible
  • Preferably they should be lying down and if they are feeling weak, dizzy or appear pale and sweating their legs should be raised
  • When dialling 999, say that the person is suffering from anaphylaxis (anna-fill-axis)
  • Give clear and precise directions to the emergency operator, including the postcode of your location
  • If adrenaline has been given, make a note of the time this was administered. A second dose can be given after five minutes if there has been no improvement
  • If the person’s condition deteriorates after making the initial 999 call, a second call to the emergency services should be made to ensure an ambulance has been dispatched
  • Send someone outside to direct the ambulance crew when they arrive
  • Try to ascertain what food or substance may have caused the reaction and ensure the ambulance crew knows this.