Childrens Services

Allergy - children's Acute Food Allergies


What is an allergy?Show [+]Hide [-]

An allergy is as a ‘harmful immune-controlled reaction to a substance that should otherwise be harmless.’ 

Your child is over-sensitive to specific foods, and reacts to them in ways that are unpleasant and sometimes dangerous.

My child had lots of different symptoms when they had their allergic reaction – what happened?Show [+]Hide [-]

All the symptoms were caused by a chemical called histamine. Histamine can cause many things to happen in your body:

  • In the skin – histamine causes blood vessels to swell and become less tightly sealed, so that they leak fluid. It causes redness and swelling to develop in the skin: the typical lumpy ‘nettle rash’, or urticaria of allergic reactions. Some people call them hives. 
  • Swelling – the leaky blood vessels can also give rise to swelling in the tissues under the skin. This can be worrying for parents, as it often affects the face, particularly around the lips and eyes. 
  • In the lungs and nose – histamine causes the lungs to produce excess mucus; the airways may tighten with wheezing, cough and breathing difficulties. In the nose, acute allergies may cause itching, sneezing, or a runny nose.
  • In the gut – Histamine causes increased movement throughout the gut, as well as increasing the production of mucus and stomach acid. This causes vomiting, diarrhoea and often crampy, colicky pains. 
  • Whole-body reactions – the most severe reactions are called ‘anaphylactic reactions’, or ‘anaphylaxis’. Large amounts of histamine can make the child very wheezy and unable to speak. Swelling of the throat may also cause serious breathing problems. In the most severe cases, children can develop low blood pressure, and loss of consciousness. Many children will vomit and have stomach cramps. Perhaps surprisingly, not all will have the rash.

Where does the histamine come from?Show [+]Hide [-]

They came from a special cell called a ‘Mast Cell’. 

These are found all over your body; but particularly in the skin, gut, nose, lungs, and eyes.

Why do the cells react?Show [+]Hide [-]

Mast cells are supposed to release histamine when they sense infection nearby.

However, in your child’s case, their body has made specific IgE antibodies to the food they are allergic to. These antibodies cover the mast cell surface, and whenever they detect the food, they trigger the mast cell to release large amounts of histamine.

What are these antibodies? And why does my child have them?Show [+]Hide [-]

Antibodies are proteins your body makes to fight infections – they are intended to protect you. 

People with acute allergies make too much of a type of antibody called IgE. IgE sticks tightly to mast cells, where it makes them oversensitive to specific triggers. Exactly why some people make too much IgE antibody is not known. Although a tendency to do it definitely runs in families, it can also happen to some children at random.

Can anything be done to get rid of the antibodies?Show [+]Hide [-]

 Unfortunately, not. Doctors are researching ways to desensitise children to food – but this is not yet a safe or proven treatment.

How do I manage my child’s diet safely?Show [+]Hide [-]

 This is a very important question, as your child needs to completely avoid whatever they are allergic to. If your child’s allergies make it difficult to get a balanced diet, your doctor should refer you to a dietician who can offer you personalised advice. Additional information may also be found on the internet.

How do medicines stop allergic reactions?Show [+]Hide [-]

How do medicines stop allergic reactions?

There are three main types of medicine used to treat allergic reactions; and all are potentially lifesaving. Some people with allergies carry an emergency pack containing all three.

  • Antihistamines – these directly block the actions of histamine throughout the body.
  • Inhalers – these medicines are inhaled to treat the asthma-like symptoms in the chest. They are usually given as a blue ‘puffer’ called salbutamol. If your child is only a little wheezy, inhalers should be enough to treat the problem. If they are really short of breath, the next medicine is required – adrenaline.
  • Adrenaline – this is a natural hormone, which has several actions:
  • It stops the release of further histamine from mast cells
  • It tightens up blood vessels everywhere, raising the blood pressure, and reducing swelling very quickly.
  • It causes the lungs to relax (like an inhaler, but stronger).
  • It makes the heart beat faster and stronger.

Adrenaline is potentially life-saving; although it won’t help very much with the stomach upset or itching. You must always go to the Emergency Department after using it.

Which antihistamine is best for my child?

Liquids work faster than tablets; which should be crunched before swallowing to make them work faster. The ‘best’ choice depends on the individual; but common antihistamines are:

  • Chlorphenamine (Piriton) – is rapid-acting, but not long-lasting, and can cause drowsiness. Usually given to children under one. 
  • Cetirizine, Loratidine, Fexofenadine and Desloratidine – all of these are rapidacting and long-lasting.
  • In Newcastle, we will always prescribe one of these – most often cetirizine.

Does my child need an adrenaline pen?

The vast majority of children with food allergies do not need an adrenaline pen; but this depends on individual circumstances, and your doctor will have discussed these with you.

Where can I get more information about allergies?Show [+]Hide [-]

Your doctor or allergy nurse should be your best source of information. There are also many websites which are helpful – these are just a few of them:

For more information about allergy testing, read the PDF on the British Dietetic Association website 

You can also download a PDF leaflet of the information on this page

Contact details

Nurse Specialist: tel 0191 282 1701 (Monday – Friday 9.00am – 5.00pm)

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