A skin prick test, also called a puncture or scratch test, checks for immediate allergic reactions to as many as 50 different substances at once. This test is usually done to identify allergies to pollen, mold, pet dander, dust mites and foods. In adults, the test is usually done on the forearm. Food allergy symptoms are caused by the interaction between a food allergen and an antibody known as IgE (immunoglobulin E). To diagnose a food allergy, your allergist may use a skin prick test (SPT) to measure the presence of IgE antibodies for the suspect food. SPTs are inexpensive, produce immediate results, and can be performed in the doctor’s office. During this test, the allergist places a drop of solution containing the food allergen on your forearm or back. (When testing fruits or vegetables, fresh food may be used instead of a solution.) Using a small plastic probe or needle, the doctor gently pricks or scratches the skin to allow a tiny amount of the solution to enter just below the surface. The SPT is generally not painful and there is no bleeding. The scratching on the surface of the skin feels similar to a fingernail scratch.