Allergic conditions are the most common health issues affecting children in the U.S., with as many as 4 in 10 kids having some type of allergy.
If your pediatrician thinks your child might have an allergy, he’ll probably refer you to an allergist for further testing. Here’s what you can expect.
An allergist will first ask you and your child several questions, such as:
- What symptoms do you notice when your child has a reaction (i.e., hives or a scratchy throat)?
- How often does the reaction happen?
- How long does it take between eating a particular food and the start of the symptoms?
- Do any family members have allergies or conditions like eczema and asthma?
Then, the allergist will perform a test. If your child is taking an antihistamine, she should stop several days before the test. It can interfere with the results by suppressing reactions.
Skin tests are the most common type of testing to diagnose allergies.
In a typical skin test, a doctor or nurse will make a small scratch or prick on the skin and then place a tiny bit of an allergen (such as pollen or food) on that spot. Allergists often do skin tests on the forearm or back. The allergist then waits 15 minutes or so to see if reddish, raised spots called wheals form, indicating an allergy.
If the doctor thinks your child might be allergic to more than one thing – or if it’s not clear what’s triggering his allergy – the allergist will probably skin test for several different allergens at the same time.
If the doctor thinks your child may be allergic to more than one thing – or if it’s not clear what’s triggering her allergy – the allergist will probably skin test for several different allergens at the same time.
Skin tests may itch for a while, so the allergist might give you antihistamine or steroid cream after the test to lessen the itching.
Food allergy testing
Doctors often use a combination of skin testing and blood testing to diagnose a food allergy. If both come up positive, there’s no need for further testing.
When a skin test shows up as positive with a certain food, that only means your child might be allergic to that food.
To diagnose a food allergy for certain, an allergist may do a blood test in addition to skin testing. If there are enough IgE antibodies to a particular food in the blood, it means it’s very likely your child has an allergy.
If the results of the skin and blood tests are still unclear, an allergist might do something called a food challenge. During this test, your child will be given gradually increasing amounts of the potential food allergen to eat while the doctor watches for symptoms.
Because food allergies can trigger serious reactions in people, this test can be risky. So it needs to be done in an allergist’s office or hospital that has access to medications and specialists to control reactions like anaphylaxis.
Doctors only occasionally use the food challenge to diagnose a person with a food allergy. Most of the time, this type of test is done to find out if someone has outgrown a known allergy.
(c) 2016. Article adapted from The Nemours Foundation/KidsHealth(R). Used under license.