Children's Food Allergies, Tests & Treatment

In the UK, 40% of children have been diagnosed with an allergy at some stage. The four most common child allergies are food allergies, eczema, asthma, and hay fever. Allergy symptoms can affect all aspects of a child’s daily life and can be equally distressing for parents.¹

What triggers food allergies?

Food allergies happen when the immune system mistakenly treats proteins in food as a threat. As a result, chemicals are released which trigger the symptoms of an allergic reaction.⁵

The immune system protects the body by producing specialised proteins called antibodies. In the most common type of food allergy, an antibody known as IgE mistakenly targets protein found in food as a threat. IgE can cause several chemicals to be released, the most important being histamine.⁵

Food allergies in children are often linked to eczema during infancy. The worse the child’s eczema, and the earlier it started, the more likely they are to develop a food allergy.¹

Food allergy symptoms

Normally food allergy symptoms appear within a few seconds or minutes of eating the food allergen.⁶

Common symptoms include:⁶

• Tingling or itching in the mouth
• A raised, itchy red rash
• Skin turning red and itchy, but without a raised rash
• Swelling of the face, mouth, throat, or other areas of the body
• Difficulty swallowing
• Wheezing or shortness of breath
• Feeling dizzy or lightheaded
• Nausea or vomiting
• Abdominal pain or diarrhoea
• Hay fever symptoms, such as sneezing or itchy eyes

Below, we have listed the most common food allergies in children.

Common food allergies

Cow’s milk allergy

ICow’s milk allergy is one of the most common food allergies in infants and young children, but most children will grow out of it by the time they reach school age (around 5 years of age). In a small number of people, it will persist into adulthood. Where this happens, people are likely to experience more severe allergic reactions.²

Egg allergy

Egg allergy is also among the most common food allergies in young children. Although some children remain allergic to eggs throughout their lives, most will eventually grow out of it. Having an egg allergy can mean being allergic to all forms of egg (well-cooked, loosely cooked, and raw) or only to loosely cooked and raw egg.²

Peanut allergy

Peanut allergy is one of the most common food allergies, affecting around 2% (1 in 50) of children in the UK, increasing in recent decades. It usually develops in early childhood but can occasionally appear in later life.²

Wheat allergy

Although allergy to wheat is one of the most common food allergies in infants and young children, most will outgrow it.³

Wheat allergy results from an adverse immunologic (IgE-mediated) reaction to proteins in wheat. Typical allergy symptoms involve the skin, gastrointestinal tract, respiratory system and, in some cases, even anaphylaxis.³

Soy allergy

Soy allergy is another of the more common food allergies in young children, but most children outgrow it.⁴

The amount and forms of soy to avoid will depend on each individual case. Some people may need to avoid all forms of soy, whereas others may be able to tolerate, for example, soy sauce and soya lecithin. In fact, most soy sauces contain very small amounts of soy, with most of the protein in the sauce being derived from fermented wheat.⁴

Food allergy tests

The type of allergy test required will be decided by your GP or specialist allergy doctor or nurse. This will be guided by the questions and information provided in an allergy focused clinical history. This is a series of questions that helps a doctor understand more about the suspected food allergy and will guide the healthcare professional to appropriate diagnostic tests and ultimately to the type of food allergy your child is suffering from.⁷

The most appropriate test will depend on the type of allergy that is suspected, which could be:⁷

• Delayed (Non IgE mediated). Symptoms occur several hours after exposure to the food allergen.
• Immediate (IgE mediated). Symptoms occur within minutes of exposure to the food allergen.

There are no clinical tests for the diagnosis of Non IgE mediated allergies, instead you will have to undergo a trial of elimination and re-introduction to see if the symptoms improve when the suspected food is removed from the diet. The food should be removed for 2-4 weeks and then re-introduced to see if symptoms return.⁷

Fortunately, testing for IgE mediated food allergies is a little more straightforward. It identifies the presence of IgE antibodies in response to the suspected food allergen through a blood test or a skin prick test, which measure levels of antibodies in the blood or in the skin. Baby allergy tests and children’s food allergy testing are available.⁷ Both blood tests and skin prick testing can be carried out on infants and children in a hospital or allergy clinic.

How to treat food allergies

There are two main types of treatment to relieve symptoms of an allergic reaction.

Antihistamines

Antihistamines are the main course of treatment for allergies, including common food allergies in children. They block the effects of histamine in the body. Histamine is normally released when the body detects something harmful such as an infection. However, in people with allergies, the body mistakes something harmless such as a food allergen, for a threat and produces histamine. The histamine causes the unpleasant symptoms of an allergic reaction.⁸

Antihistamines help prevent this process if taken before you come into contact with allergens or they can reduce the severity of your symptoms if taken afterwards.⁸

Some antihistamines, such as alimemazine and promethazine are not suitable for children under the age of 2.⁹

Adrenaline

Adrenaline works by narrowing the blood vessels to counteract the effects of low blood pressure and opening up the airways to help ease breathing difficulties.⁹

Auto injectors such as EpiPen’s are essential in the case that you or your child is at risk of anaphylaxis (severe allergic reactions) or have experienced a previous episode of anaphylaxis. It’s important to train your child to use it when they are old enough.⁹