patch test, a skin test for identifying allergens, especially those causing contact dermatitis. The suspected substance (food, pollen, animal fur) is applied to an adhesive patch that is placed on the patient’s skin. Another patch, with nothing on it, serves as a control. After a certain period (usually 24 to 48 hours) both patches are removed. If the skin under the suspect patch is red and swollen and the skin under the control area is not, the test result is said to be positive, and the person is probably allergic to that substance. Compare radioallergosorbent test.
