Allergy testing in children identifies specific triggers impacting their health. Pinpointing these allergens helps manage symptoms and improve a child’s well-being. Understanding the process can help parents feel prepared for their child’s diagnostic journey.
Preparing for Your Child’s Allergy Test
Before an allergy test, discuss any medications your child is taking with their doctor. Antihistamines, found in many allergy, cold, and sleep medications, can interfere with test results by suppressing allergic reactions. Children may need to stop short-acting antihistamines for 48 hours and long-acting ones for five to seven days before the test. Asthma medications and oral steroids typically do not need to be stopped.
Parents should avoid applying lotions or creams to the testing area, such as the back or forearm, for several days prior. Bring a list of symptoms, their timing, and suspected allergens for the allergist. Prepare your child by explaining the procedure in simple, age-appropriate language to reduce anxiety. Bringing a comfort item or distraction can be helpful.
Types of Allergy Tests for Children
Skin prick tests and blood tests are the most common methods to identify allergens. A skin prick test involves placing small amounts of allergen extracts on the skin, typically the forearm or back. This method helps determine immediate allergic reactions to environmental triggers like pollen, dust mites, pet dander, and certain foods. It is generally suitable for children over six months old.
Blood tests measure allergen-specific IgE antibodies. A blood sample is drawn and analyzed in a laboratory to detect IgE antibodies produced in response to specific allergens. Blood tests are often used when skin conditions like eczema make skin testing difficult, or when a child cannot stop taking antihistamines. While results take longer than skin tests, they provide information about allergic sensitivities.
Oral food challenges are conducted under strict medical supervision, especially when initial test results are inconclusive or to assess if a child has outgrown a food allergy. During this procedure, increasing amounts of a suspected food allergen are given to the child, who is then closely monitored for any reactions. This type of challenge is considered the most accurate way to diagnose a food allergy or confirm if it has been outgrown.
What Happens During the Allergy Test
During a skin prick test, a healthcare professional cleans the chosen skin area, typically the back or forearm. Small drops of allergen solutions are placed on the skin, each corresponding to a potential trigger. A sterile lancet gently pricks the skin through each drop, allowing a tiny amount of allergen to enter just beneath the surface. The pricking is usually described as a light scratch or quick pinprick, causing minimal discomfort.
After the allergens are applied, there is a waiting period, typically 15 to 20 minutes, for a reaction to develop. If a child is allergic to a substance, a raised, red, itchy bump, similar to a mosquito bite, will appear at the site of that specific allergen. The size of this reaction, known as a wheal and flare, is then measured by the healthcare provider. The test application takes only a few minutes, and any itching typically subsides within 30 to 45 minutes.
For a blood test, a small blood sample is collected, usually from a vein in the child’s arm. For infants, a heel prick may be used. The procedure is similar to a routine blood draw and takes only a few minutes. The blood sample is then sent to a laboratory for analysis, identifying specific IgE antibodies associated with various allergens. It is a safe procedure with minimal risks, such as a small bruise or mild soreness at the injection site.
Understanding Your Child’s Allergy Test Results
Interpreting allergy test results requires careful consideration by an allergist. A positive test indicates sensitization (the body has produced IgE antibodies), but not necessarily a clinical allergy. For skin prick tests, a positive reaction is typically identified by a wheal of at least 3 millimeters larger than the negative control. The size of the wheal can correlate with allergy likelihood, with larger reactions often indicating higher probability. However, even a significant wheal does not always mean a child will experience symptoms upon exposure, and smaller reactions may indicate sensitization without a full clinical allergy.
Blood test results provide numerical values for specific IgE antibodies, often reported in kilounits per liter (kU/L) or international units per milliliter (IU/mL). Higher numbers suggest a greater amount of allergen-specific IgE. Similar to skin tests, an elevated IgE level indicates sensitization, but the allergist will consider this with the child’s symptoms and medical history for an accurate diagnosis. Normal IgE levels do not completely rule out an allergy.
A comprehensive diagnosis integrates test results with the child’s detailed clinical history, including observed symptoms and potential triggers. The allergist will discuss the findings and develop a management plan that may include allergen avoidance strategies, medication, or other treatments. A follow-up consultation ensures parents understand the results and next steps for managing their child’s allergies effectively.