How common are food allergies in children?

In our modern world, it seems like the prevalence of allergies is on the rise – with very little sign of stopping any time soon. Allergies are extremely common, with an estimated 1 in 4 people in the UK affected by an allergy in some form. As we become more and more aware of allergies and their various forms, it’s natural that we might be worried or nervous about our children being introduced to new types of food that they could be allergic to. Dr Adam Fox, one of the UK’s leading paediatric allergists, explains what parents need to know about food allergies, and how you can help spot the symptoms in your child.

Just how common are food allergies in children?

While food allergies may be on the rise, it’s important to note that incidence of food allergies in babies is actually rather small, at about 5-6%. The other good news is that many babies and young children in fact grow out of their allergy. Milk and egg allergies are the most common types affecting babies and young children, but they tend to disappear during childhood.

Just why there has been such an increase in allergies in recent years is not quite clear, but it has been proposed that our immune systems do not have to deal with the same amount of germs and bacteria as they once did, thanks to the cleaner environment we live in compared to in the past.  A less ‘mature’ immune system is more likely to develop inappropriate responses to harmless foods.

What causes food allergies?

A food allergy happens when the immune system reacts inappropriately to a particular food– the body is confused, and the food proteins trigger a reaction which releases histamine, a chemical your immune system releases to fight off parasitic infections. Histamines are part of your body’s natural defence system, but in those with an allergy, the immune system reacts to a normally harmless substance. Histamine causes the symptoms of an allergic reaction.

Food allergies are more common in children who come from families with a history of allergies, but it is babies who have eczema who are in fact most prone to developing a food allergy. If your baby has significant or early onset eczema, it’s a good idea to consider having them tested for food allergies before weaning, because if you delay the introduction of allergenic foods, their risk of developing an allergy may be higher.

How are food allergies diagnosed in children?

In order to diagnose a food allergy in a child, an examination is needed, along with a careful study and analysis of your child’s medical history (and, where appropriate, family allergy history), and finally, allergy testing.

With immediate type allergies (where a reaction is triggered immediately after exposure to the allergen), testing can be done by a blood test or by a ‘skin prick’ test, where food extracts are placed on the skin of the arm and gently pricked. However, with delayed allergies (where a reaction is not immediate), testing is not so straightforward, though exclusion diets followed by reintroduction may provide information.  

Once an allergy has been diagnosed, your child’s doctor will help you come up with a treatment plan, which generally involves avoiding the allergen and foods which contain it, or may involve desensitisation (deliberate exposure to reduce the degree of reactivity).

How can I spot the symptoms of a food allergy?

In some cases, food allergies may be quite easy to spot, especially in cases of immediate type allergies. Sometimes, however, symptoms can be less obvious and the food allergy may be difficult to detect because of this – especially in delayed type allergies. Unlike in immediate type allergies, where histamine is released straight away, delayed allergies involve parts of the immune system which take much longer to respond.

Symptoms of an immediate food allergy include:

• Mild swelling, especially of the eyes, lips, and face.
• A flushed face, hives (raised itchy bumps), a red itchy rash on the face around the tongue, mouth, or eyes. These symptoms can spread across the body.
• A runny or blocked nose, sneezing.
• Watery eyes.
• Tummy cramps, diarrhea, nausea, and vomiting in some cases.
• A scratchy or itchy feeling in the throat.

If the allergy is more serious it may cause severe symptoms (called anaphylaxis). If these symptoms present your child needs urgent medical attention:

• Wheezing or tightness in the chest, like in an asthma attack.
• Swelling of the tongue or of the throat, or both, restricting the airways. You may be able to spot this through noisy breathing, a cough, or a change in voice.
• A sudden drop in blood pressure (hypotension) which leads to shock.
• Dizziness, confusion, collapse, loss of consciousness, or in some cases, coma.

Symptoms of a delayed food allergy include:

• Eczema
• Reflux - an effortless vomiting
• Poor growth
• Swelling in the small bowel
• Constipation and/or diarrhoea
• Raising knees to chest with tummy pain
• Frequent distress and crying

However, these symptoms are not limited only to allergic reactions, and allergy could be but one possible explanation. Identifying if an allergy is the problem can be very difficult and may require the help of an experienced doctor.

How can I be sure my child has a food allergy?

If you suspect your child has any type of allergy, take them to see their paediatrician or your local GP. If the allergy is obvious, with a clear cause, your doctor can offer advice and treatment. However, in certain cases, your child may need referral to a specialist allergy clinic, and a paediatric allergist, who can identify your child’s allergy and come up with a treatment plan for you and the family to follow.

If you are concerned about symptoms in your child and suspect it to be a food allergy, or you would like to discuss treatment plans with a specialist, make an appointment with a paediatric allergist.