Intradermal allergy testing is a skin test used to help identify the substance(s) to which you are allergic. It is used when the preferred method of allergy testing, the skin prick test, fails to yield positive results to a suspected allergen.
Intradermal Allergy Testing & Skin Prick Testing
In a skin prick allergy test, a prick or scratch is made on the skin (usually somewhere on the arm or back). A drop containing the suspected allergen is placed on this area and allowed to penetrate the skin. Redness or swelling indicates a positive result. Skin prick tests are sometimes inconclusive. If the allergist believes the substance administered is the one responsible for symptoms despite this result, an intradermal allergy test may be administered.
Intradermal allergy testing involves injecting the allergen directly into the skin, and provides more sensitive results quickly – usually within twenty minutes. Small red hives on the skin mean a positive result.
This type of test is useful for finding out if the patient has a very specific allergy, such as penicillin.