Allergy Testing for Children: What to Expect?

Allergy Testing for Children: What to Expect?

Allergic diseases are frequently encountered in kids, affecting up to 30-35% of children. These diseases include: eczema, food allergies, allergic rhinitis and asthma. The symptoms can develop at any age and can range from sneezing and runny nose in allergic rhinitis, to life-threatening anaphylaxis that causes breathing difficulty in children with food allergies. Allergies can also be triggered by household allergens like dust mites, or environmental irritants like haze/ smoke.


How Are Allergies Diagnosed In A Child?

Your child’s doctor will first take a detailed history from you, and examine your child looking for signs of allergies. If needed, they will also perform tests that will help determine what triggers the allergy symptoms.

 Some of the common forms of allergy testing include:


1. Skin prick test

This is a simple test that can be performed for your child in the clinic. It identifies possible allergies to mould, certain foods, dust mites, or animal dander.

A small drop of an allergen is applied to the skin either on your child’s forearm or back. The skin is scratched or pricked which will allow the allergen to get into the skin. If your child is allergic to any of the substances that are introduced into the skin, a small itchy red bump (similar to a mosquito bite) will appear in about fifteen to twenty minutes. Although the interpretation of the reaction will be completed in less than an hour, the time taken for this test depends on the number of allergens being tested. The red bumps usually disappear within a few hours.


2. Specific IgE allergy blood tests 

Similar to the skin prick test, specific IgE blood tests are available to check for possible allergies in your child to allergens like house dust mites, mould, pollen and foods. Blood tests are useful in children who have skin conditions and are not able to do skin prick tests. They are also useful in children who are on regular antihistamines (allergy medications) as skin prick tests are not accurate while your child is taking these medications.

The allergy blood tests involve measuring blood levels of IgE antibodies to certain allergens. Total blood IgE and eosinophil counts may also be performed. Eosinophils are a kind of white blood cell that increases in allergies.

A needle is used to obtain 5-10 ml of blood from your child, depending on the number of allergens being tested. The test results take longer to return as they are processed in the hospital laboratory (1-2 weeks on average) and generally cost more than the skin prick tests. Regular medications like antihistamines, do not interfere with test results. Many more different allergens can be tested by this method, however, as blood is needed to be drawn from your child, it can be painful and more scary for young children.


How To Prepare Your Child For Allergy Testing?

If your child is currently on anti-allergy medications like oral antihistamines, the drug should be temporarily stopped a week before the skin prick test as they interfere with test results. Inform your child’s specialist if your child is on any medication. Do not use lotions, powders, or perfumes on the day of testing. Your child’s doctor will obtain a full medical history and perform a thorough clinical examination. This information will be used to determine the number and type of allergens to be used for testing.


What Do The Results Mean?

A positive skin or blood test to an allergen is useful to help identify the triggers for an allergic condition. However, in some instances, having a positive test may not necessarily mean a definite allergy. Conversely, a negative result does not always rule out allergies. False negative results may occur in skin testing. Certain allergies are also triggered via a different mechanism/ pathway in the body.



An allergy test is a useful and effective way to help identify the cause of allergies in most children. If your child has recurring symptoms that suggest an allergy, you should conduct further tests to identify the cause of the allergy. 


Medically reviewed by Dr. Petrina Wong

[This article was reproduced with permission from SOG. Original Article can be found here.]

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