Anaphylaxis guide for parents

Anaphylaxis is a severe and often sudden allergic reaction. It can occur when someone with allergies is exposed to something they are allergic to (known as an allergen). Reactions usually begin within minutes and rapidly progress, but can occur up to 2-3 hours later.

It is potentially life-threatening, and always requires an immediate emergency response.

An allergic reaction occurs because the body’s immune system reacts to a substance that it wrongly perceives as a threat. The body produces an “allergy” antibody called Immunoglobulin E (IgE), which sticks to the substance (“allergen”) and causes the release of chemicals such as histamine (this is why antihistamines are used for mild reactions):

  • In the skin, this causes an itchy rash, swelling and redness
  • In the stomach and gut, it can cause nausea, cramping pains and vomiting

Anaphylaxis occurs when the reaction spills over into the bloodstream, causing more widespread symptoms that affect the whole body, including the airway and breathing. Most allergic reactions do not become anaphylaxis, even in someone who has had anaphylaxis before. Very severe, life-threatening allergic reactions are very rare, but are also unpredictable. This is why ALL anaphylaxis reactions must be taken seriously and receive immediate treatment.

What can cause anaphylaxis?

Common allergens that can trigger anaphylaxis are:


(e.g. peanuts, tree nuts, milk/dairy foods, egg, wheat, fish/seafood, sesame and soya)


(e.g. antibiotics, pain relief such as ibuprofen)


(e.g. rubber gloves, balloons, swimming caps)


(e.g. bee, wasp)

Food is the most common cause of anaphylaxis in children. In the UK, most severe reactions are caused by cow’s milk, peanut, tree nuts and fish/seafood.

It is very unusual for someone with food allergies to have anaphylaxis without actually eating the food. Coming into contact with an allergen might trigger a local skin reaction, but is very unlikely to trigger anaphylaxis. However, if the allergen gets on to some food which the person then eats, this can then trigger a reaction.

What are the symptoms of anaphylaxis?

Most healthcare professionals consider an allergic reaction to be anaphylaxis when it involves the breathing or affects the heart rhythm or blood pressure. Stomach/gut symptoms with or without skin signs are not anaphylaxis, unless the reaction is due to an insect sting (as then the sting has caused the release of chemicals which have travelled to the gut, indicating a more widespread reaction).

In anaphylaxis, any one or more of the following symptoms may be present:


  • Persistent cough
  • Vocal changes (hoarse voice)
  • Difficulty in swallowing
  • Swollen tongue


  • Difficult or noisy breathing
  • Wheezing (like an asthma attack)


  • Feeling lightheaded or faint.
  • Clammy skin
  • Confusion
  • Unresponsive/unconscious (due to a drop in blood pressure)

Usually, other less severe symptoms (such as an itchy, raised rash (hives), feeling or being sick, lip/face swelling, or stomach pain) are also present. However, sometimes, this does not happen and only severe symptoms are seen.

In children – even those without asthma – the most common type of anaphylaxis involves the airway/breathing, similar to an asthma attack. The throat can tighten, causing swallowing difficulties and a high-pitched noise (stridor) on breathing in.

How is anaphylaxis treated?

The first line treatment for anaphylaxis is adrenaline (epinephrine), given by an injection into the outer muscle of the mid-thigh (upper leg).

Adrenaline given this way is safe. It starts to work within minutes, reducing swelling, relieving wheeze and improving blood pressure. It also stops “allergy” cells from releasing more chemicals into the blood – so the earlier it is given during anaphylaxis, the better. Other “allergy” medicines (such as antihistamines) can help with mild symptoms, but are not effective for severe reactions (anaphylaxis).

Outside hospital, adrenaline can be safely given by parents, teachers and other non-healthcare workers into the mid-thigh muscle using an adrenaline auto-injector (AAI). Current brands available in the UK are EpiPen®, Emerade®, Jext®.

Giving adrenaline can be lifesaving, and should be administered at the first signs of anaphylaxis.

Some anaphylaxis reactions require more than a single dose of adrenaline; children can initially improve but then get worse later. Therefore always dial 999 and request an ambulance whenever anaphylaxis has occurred – even if there has been a good response to an adrenaline injection.

IF IN DOUBT, give adrenaline.


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