Testing for environmental allergies (pollen, molds, animals, dust mites), foods, stinging insects and medications is typically done on the skin to check for an immediate allergic reaction. This allows us to complete the work-up in one office visit. Testing is based upon each patient’s history of allergy symptoms including timing and severity, and is performed on the forearm or back, and sometimes on the upper arm. In some cases, testing for multiple allergens is performed. Allergy testing may involve two parts, depending on the reason for the test.
Initial testing is done using a disposable single or multi-test device. These devices deposit a small amount of allergen by gently pricking the surface of the skin. This is known as a skin prick test. Any discomfort experienced is minimal and in many cases there is no discomfort noted at all. After 15 minutes, test results are “read”. A positive test looks like a small red bump on the skin, similar to a mosquito bite and may be itchy. It is measured by the nurse performing the test and recorded for interpretation by the physician.
For non-food allergy testing, the physician often asks for a second test to be performed using the allergens that were found to be negative during the first test. This is done using a needle to inject a small amount of allergen between the layers of the skin on the upper arm, and is known as an intradermal test. After 15 minutes, test results are “read” using the same process performed following the skin prick test.
Testing for contact allergies such as reactions to cosmetics, sunscreens, certain metals, and other substances involves the use of a “patch test”. This test is performed by placing test allergens into small chambers which are then taped to the back. This is a delayed reaction type of test and requires three visits to the office: one for initial application, one for an initial reading 48 hours after application, and one for a final reading and interpretation 48 hours after the initial reading. A positive reaction can range from a small skin rash with a little swelling to red, blistered skin.
Allergens used for skin testing and patch testing are approved for use and manufactured in accordance with standards established by the Food and Drug Administration.