Intradermal Allergy Testing

Allergy tests involve the introduction of a small amount of allergen into the body under controlled and supervised medical conditions. Such tests are conducted in order to observe and analyze the nature and seriousness of the ways in which a person’s immune system reacts to the certain substances. Generally, for testing a person for skin allergies, minute punctures are made on the surface of the skin to obtain more specific results. This procedure, known as puncture testing or prick testing in common parlance, is quite painless and less expensive than blood sample testing that is recommended for other kinds of allergies. There is no special preparation that you need to take before the test is conducted. You should of course inform your doctor about your past medical history including illnesses and past allergic attacks, any previous allergy tests that you might have undergone and the results thereof, medicines you consume regularly, as well as your eating habits, lifestyle, home and work environment and emotional state. You are advised not to consume antihistamines before an allergy test as they may interfere with the test results.

Procedure to Conduct Allergy Tests

The actual process involves introducing a sample of the suspected allergen (grass, pollen, food extracts, mite proteins, insect venom, penicillin, and the like.) on the sites on the skin already marked out with dye or a pen, usually on the back or the inner side of the forearm. Following this, a small plastic or metal device is used to make a fine incision on the skin and introduce a minimal amount of the allergen inside the skin. Sometimes, a syringe may also be used to inject the allergen into the skin. Since the allergen is introduced between the layers of the skin, the procedure is technically known as intradermal allergy testing. If the person is allergic to the specific substance that has been introduced into the skin, s/he develops common allergic symptoms like redness or swelling on the skin within 20 to 30 minutes after the injection. The medical examiner obtains readings of the diameter of the skin inflammation as well as observes the intensity of the reaction through visible signs like color. The test result is usually shown as + or –, indicating whether the person is allergic to that particular substance or not. A +/ – result means that the person has borderline allergy to the specific substance. A test result of +4 or more is indicative of a serious allergic condition.