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Diagnosis of Allergies in Children

If you suspect that your child’s symptoms may be caused by allergy, then it is important to go to your GP for further advice. Your GP can give you advice and guidance, and, if appropriate, refer you to a specialist allergy clinic for testing and diagnosis.

To help your doctor, try to think when your child had symptoms, and note the date, time of year and how long they lasted. Think back about your child’s diet previously, and what activities they were doing, and try to record all these details so the doctor can get a clear picture of what has happened. Some doctors may give you a symptom diary to fill in, where you can record all this information since these clues can lead to a quicker diagnosis. You can find an example of a symptom diary here.

Although it is often thought that babies cannot be tested for allergies, this is in fact not true. However, allergy tests can be difficult to interpret in babies and younger children. A positive test may not mean a child is allergic. It is therefore important that allergy tests are requested and interpreted by a doctor with experience of allergy in this age group, for example a paediatric allergy specialist. However, it is not always easy to get access to paediatric allergy specialists as there are very few of them in the country, but sometimes knowing where you can be referred to can be of help to your doctor.

It is possible to be referred to an allergy clinic even if it is outside of your local healthcare area. Further advice on how to get referred to an allergy specialist, and details of the nearest allergy clinics to your area, can be obtained by contacting Allergy UK. 

Paediatric allergy clinics are run in a number of hospitals around the country. The paediatric allergists who work in these clinics are doctors and consultants who specialise in children’s allergy, and have an in-depth knowledge of the causes and symptoms of each allergy. These clinics are part of the services offered through the NHS, and can provide your child with the appropriate treatment for their condition.

While allergy research continues to try to find answers for all the causes of allergies and how to prevent them, there is much information that can be misleading or misinterpreted. Studies must be repeated and assessed before their conclusions can be known to be correct, and not all the results for allergy research in adults can be applied to allergy care in children.

It is for these reasons that it is especially important that, when attending an allergy clinic, you see doctors specifically trained in dealing with childhood allergies. If you are at all unsure how to gain access to this specialist care, contact the Allergy UK helpline.

Once you have an appointment with a paediatric consultant, or allergy specialist, is it important to read any information that you may be sent about your child’s appointment beforehand, or call the clinic to check if there are any special instructions.

The first step to diagnosis

The first step in making an accurate diagnosis is always to take a detailed medical history. This history is vital, and will allow the doctor to make judgements about your child’s condition based on the previous medical experience of your child and family.

Information that is useful to your doctor will include whether there is a history of allergy in the family, a description of the symptoms, which triggers seem to cause allergic reactions, and any recent changes in your child’s health. 

It is important to answer questions as fully as possible, as even things which you may not think of as relevant may hold a clue for the doctor about your child’s condition.

Once a history has been taken, the doctor may organise testing. There are four main types of tests used to work out if an allergy exists and which substance or substances are causing your child’s allergy symptoms:

1. Skin Prick Test                       

A tiny amount of the allergen to be tested is put on the skin, usually in liquid form. Each drop of liquid is then pricked with a tiny needle, which punctures just the top layers of skin. After 15 to 20 minutes, the tester (often a nurse) will check what reaction has happened on the skin. For information, click here.

2. Blood Test

The blood test used to test for allergies is called a specific IgE blood test (previously called a RAST test). A small blood sample is taken and then tested in the laboratory to measure the amount of IgE antibodies produced when the blood is tested against a range of allergens. For information, click here.

3. Patch Test

A patch test is used to find the allergic cause of contact eczema and other types of skin reactions. A range of suspected allergens are placed onto a metal disc or strip, which is then taped to the patient’s back and left in place for 48 hours. The testing strip is then removed and a doctor or nurse looks to see if a reaction has happened on the skin. For information, click here.

4. Challenge Test

Unfortunately, none of the above tests is 100% reliable in diagnosing food allergy. The only way to be certain that an allergy is present is to give the child the food in question under carefully controlled conditions. This is called a challenge test, and should ONLY be performed at hospital, with supervision by qualified medical staff and access to the necessary medical equipment. For information,click here.


Last updated: December 2013            Next review date: December 2016
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