Pediatric allergy testing identifies specific substances, known as allergens, that trigger an immune response in a child’s body. Testing is performed when a child exhibits symptoms suggesting an allergy, such as chronic runny nose, wheezing, persistent eczema, or adverse reactions to food. The procedure helps pinpoint the exact environmental or food triggers responsible for conditions like allergic asthma, hay fever, or food allergies. This diagnostic testing is a standard and safe procedure conducted under medical supervision.
Preparing for the Appointment
Preparing for a child’s allergy test requires managing their medication schedule, especially antihistamines. These medications block the allergic response and can interfere with skin testing accuracy, potentially causing a false negative result. Oral antihistamines, such as cetirizine (Zyrtec) or loratadine (Claritin), must typically be stopped for five to seven days before the appointment.
Parents should review instructions for other medications, including certain over-the-counter cold medicines, sleep aids, and some acid-reflux drugs, as these may contain hidden antihistamines. Non-antihistamine asthma medications, such as inhaled steroids or leukotriene modifiers, are generally safe to continue. Bringing a detailed log of the child’s symptoms and any prior test results provides the allergist with a complete medical picture. Ensuring the child is comfortable, well-rested, and has eaten a regular meal helps them remain cooperative during the visit.
Common Methods of Allergy Testing
Identifying specific allergies relies on principal testing methods that measure the body’s immune reaction to an allergen. The most frequently used method is the Skin Prick Test (SPT), also called a percutaneous test. This test involves applying a small drop of liquid allergen extract onto the skin, usually the forearm or back. A tiny device gently pricks the top layer of skin through the drop without drawing blood. A positive result occurs when IgE antibodies react to the allergen, causing a localized hive or wheal.
Another technique is the blood test, which measures allergen-specific Immunoglobulin E (IgE) antibodies in the bloodstream. This method is used when a child cannot stop taking necessary antihistamines or has severe eczema that makes skin testing difficult. Blood tests avoid medication withdrawal but are generally less sensitive than skin tests, and results take several days to return from the lab. For suspected allergic contact dermatitis, a delayed reaction, a Patch Test is used. Allergens are secured to the skin on patches for 48 hours, and results are read days later.
During the Testing Procedure
The appointment typically begins with the allergist reviewing the child’s medical history and current symptoms. The skin prick procedure is quick, often taking only a few minutes to apply multiple allergens. For infants and young children, the back is the preferred site, as it provides a larger, flatter testing area while the child sits comfortably on a parent’s lap. Older children usually have the test performed on the inner forearm.
The sensation of the skin prick is often described as a light scratch or a feeling similar to a toothpick pressing on the skin, not an injection. The goal is to barely break the skin surface, making bleeding uncommon. After the allergens are applied, there is a waiting period of 15 to 20 minutes for immediate reactions to develop. If a reaction occurs, the tested areas may become itchy; parents can help by gently blowing on the area or distracting the child. The total appointment time, including consultation and observation, usually spans one to two hours.
Understanding Results and Follow-Up Care
Skin Prick Test results are typically ready immediately after the 15-to-20-minute waiting period. A positive reaction appears as a raised, red, itchy bump, called a wheal, surrounded by a flare of redness, resembling a mosquito bite. Medical staff measure the size of the wheal to help determine the degree of sensitivity to that specific allergen. A positive test confirms the child is “sensitized” to an allergen, meaning they have IgE antibodies against it. The allergist interprets this result alongside the child’s history to make a final diagnosis.
Blood test results require a few days to a week to process, as the sample must be analyzed in a laboratory. Once the diagnosis is confirmed, the allergist creates a comprehensive allergy action plan with the family. This plan includes strategies for allergen avoidance, prescription of appropriate medications, and education for caregivers and school staff. Follow-up care may involve further treatments such as allergy shots (immunotherapy) or, for food allergies, a supervised plan like Oral Immunotherapy (OIT) to gradually introduce the allergen.