Paediatric allergy: food allergy, eczema and allergy testing in children

Allergy happens when the immune system overreacts to something harmless, such as a food, pollen, dust mite, animal dander, medicine or insect sting. In children it often appears alongside eczema, asthma and hay fever, which together are sometimes called the atopic conditions.

Children with significant allergy are usually seen by a paediatrician with a special interest in allergy, or a consultant in paediatric allergy and immunology, supported by allergy nurses and dietitians. The British Society for Allergy and Clinical Immunology (BSACI) is the national professional body and lists allergy clinics. For adults and children alike, allergy care is partly a matter of getting the diagnosis right and partly of teaching families how to live safely with it.

Many children with allergy are looked after mainly in primary care. NICE has produced guidance describing which symptoms should prompt a GP to consider food allergy and when to refer on, and the NHS suggests seeing a GP if you think your child may have a food allergy.

Allergy takes different forms, and the pattern of symptoms and their timing is often the most useful clue.

• IgE-mediated food allergy, with symptoms such as hives, swelling, vomiting, wheezing or collapse, usually within minutes to two hours of eating the food. The NHS says symptoms can sometimes appear days later.

• Non-IgE-mediated food allergy, which tends to be slower and involves the gut and skin, for example in some babies with cows' milk protein allergy, with reflux, loose stools or worsening eczema.

• Anaphylaxis, a severe allergic reaction that the NHS describes as life-threatening and starting within minutes of exposure.

• Eczema, which can be worsened by food or environmental allergy in some children but is not caused by allergy in every case.

• Allergic rhinitis (hay fever or year-round nasal allergy), which the NHS says causes sneezing, a runny or blocked nose and itchy eyes, usually worst from late March to September for pollen.

• Chronic urticaria, drug allergy, venom allergy and, occasionally, rarer conditions of the immune system.

The NHS lists skin-prick tests, blood tests and supervised elimination diets as the main approaches for food allergy, sometimes supported by a food and symptoms diary. A positive test shows sensitisation, which means the immune system has made antibodies, but it does not by itself prove that a child will react, so results are always interpreted with the history.

For food allergy the core of treatment is avoiding the food, recognising reactions early and having an emergency plan. The NHS says specialists give an allergy action plan, antihistamines for mild reactions and adrenaline auto-injectors or a nasal spray for severe reactions, and that two devices should be carried at all times if prescribed.

Many children outgrow milk and egg allergy. In some cases clinics use graded reintroduction, often called a milk or egg ladder, in which a small amount of baked or heated food is introduced step by step under dietetic advice. This is a decision for a clinician, not a do-it-yourself plan, and it is not suitable for children who have had severe reactions.

The NHS says children with peanut allergy may have immunotherapy to make them less sensitive to peanut, but they should still avoid eating peanuts. Oral immunotherapy for peanut and other foods is delivered by specialist centres, while allergen immunotherapy is also used for severe pollen and house dust mite allergy. Allergic rhinitis is treated with avoidance, antihistamines and steroid nasal sprays, with immunotherapy considered if those do not work.

Practical management includes label reading, nursery and school care plans, adrenaline devices in date and with the child, and dietitian support to keep the diet balanced. The NHS advises not cutting foods from the diet without speaking to a GP.

On the NHS, a GP assesses the history and may start with advice, a short elimination trial or tests, then refers children with severe reactions, multiple allergies, faltering growth or diagnostic doubt to a paediatric allergy service. Emergency departments and 999 services manage acute reactions and the NHS says someone treated for anaphylaxis may be referred to an allergy specialist for tests and advice afterwards.

Private paediatric allergy clinics usually see children after a GP or paediatrician letter and often provide skin-prick testing, specific IgE testing and food challenges. Be cautious with tests sold outside clinical care and discuss any result with a GP or paediatrician before changing a child's diet. Ask whether the clinic can carry out food challenges safely, who is present if a reaction happens and what follow-up and school paperwork are included in the price.

• Bring photographs of any rash or swelling, a food and symptom diary, and the labels of foods involved.

• Ask what the diagnosis is, which foods must be avoided and which are safe, including baked or processed forms.

• Ask for a written allergy action plan and a demonstration of the adrenaline device, and ask how often to check expiry dates.

• Ask when and how the allergy will be reviewed and whether a supervised challenge or reintroduction might be possible.

• Ask what to tell school or nursery and who is responsible for the plan.

• Call 999 if a child has swelling of the lips, mouth, throat or tongue, fast or difficult breathing, blue, grey or pale skin, or becomes limp, floppy, confused or drowsy, and use an adrenaline device straight away if one has been prescribed, then call 999 even if they seem better.