Intradermal (ID) testing is less commonly needed, but can behelpful in the diagnosis of suspected drug, venom, or vaccine allergies. With ID testing, which is approximately 1000x stronger than skin prick testing, very small amounts (0.02ml or 1/1500 of an ounce) of the potential allergen are injected with an extremely tiny needle into the surface layer of the skin, much like a screening test for tuberculosis. The injection site is then monitored for a local reaction for 20 minutes, which may suggest an allergic response.

ID testing is not generally used for suspected food or environmental allergies.