Know When to Have Your Child Tested for Allergies and What to Expect
"When should my child be tested for allergies?"
This question is very common, which is unsurprising when you consider that allergies are the sixth leading cause of chronic illness in the U.S., according to the Centers for Disease Control and Prevention. When and how you approach allergy testing depends on multiple factors. Doctors must examine the type of symptoms or clinical reaction observed, the age of the patient, and the type of protein, or allergen, causing the reaction. Allergens can be foods, environmental or other common triggers, such as insect venoms or medications.
When to Test
Children who develop food allergies can have positive allergy tests during infancy, although the tests can be less accurate at this age. During the first year of life, a child can also develop allergies to indoor allergens such as pet dander and dust. Allergies to outdoor pollens—including trees, grasses and weeds—are uncommon during the first several years of life, and typically develop around school age. Therefore, testing for these seasonal pollens is usually done after 3 years of age.
It is important to know that allergy testing should never be performed without taking a thorough medical history to determine the symptoms that occur with allergen exposure. Broad allergy testing panels performed without a detailed history are generally not helpful and can result in unnecessary medical intervention or dietary changes.
Types of Tests
There are two ways to test for allergies: skin testing and blood (specific “IgE”) testing. Skin testing is performed using a skin prick test device which is a small, plastic device that is dipped into an allergen extract and then used to prick the surface of the skin. Some allergists will utilize individual skin prick devices while others will use a larger grid that allows multiple allergen pricks to be performed at the same time. The good news for those afraid of needles: Needles are not commonly used to perform food or environmental skin testing in children, but may be needed in cases of drug or insect allergy.
After using the skin prick test device, the skin is monitored for approximately 15 minutes. If the test is positive, the child will develop a wheal (also known as a hive) on that area of the skin. This method will be performed for each allergen that is being tested.
Skin testing is well tolerated by most children but can be associated with a small amount of pain in the area where the skin prick is performed. Most pain will usually resolve within minutes. With positive testing, children may also experience itching at the test site; more significant reactions, such as anaphylaxis, are very rare. Skin testing can be influenced by taking oral antihistamines such as Benadryl, Zyrtec, Claritin, Allegra and many cold/cough medications, so these medications need to be stopped five days prior to any skin testing.
Blood allergy testing can also be used to determine if a child has an allergy. Previously known as “RAST” testing, blood testing measures IgE antibodies produced against a specific allergen. This type of testing is not influenced by taking oral antihistamines, thus these medications do not need to be discontinued prior to blood IgE testing.
Talk to Your Doctor
Allergy testing plays an important role in appropriate management of environmental, food, drug and venom allergies. By identifying allergic triggers, families can make appropriate environmental or dietary modifications to minimize risk of future exposure or allergic reaction.
The most important part of the allergy evaluation is the detailed history performed by a trained and knowledgeable health care provider which can be used with allergy testing to develop an integrated treatment plan. For more information about allergy testing or to find an allergist in your area, visit the American Academy of Allergy, Asthma & Immunology at AAAAI.org.
Dr. Robert Pesek is director of allergy clinics at Arkansas Children’s Hospital, specializing in food allergy and eosinophilic gastrointestinal disorders. Dr. Amy Scurlock is an allergist and immunologist at Arkansas Children’s Hospital, with an interest in the basic immunology of food allergy. Both Dr. Pesek and Dr. Scurlock are professors of pediatrics and allergy/immunology in the UAMS College of Medicine.
