Intradermal allergy testing, also known as a skin patch test, is usually a group of tests that are performed on a person in order to determine the kind of substance a person is allergic to. Though there are many methods of testing for an allergy, the most common ones are skin tests and the elimination type tests. Blood tests may also often be performed for identifying allergies.
The most common of all the intradermal allergy tests are the skin tests. There are specific methods applied for skin tests, which may vary from lab to lab. In skin tests, the most common used test is the prick test. In the prick test, a small amount of the suspected allergen is placed on the skin, usually on the upper arm, forearm, or back. The skin on the particular area is then pricked, allowing the suspected allergen to reach inside the skin surface. During this time, the doctor or lab technician watches the skin closely, looking for any dermal or intradermal changes.
It usually takes about 15-20 minutes for the symptoms of allergy to appear on the skin surface. There may be a slight swelling accompanied by redness and soreness. The advantage of this testing method is that several allergens can be tested at the same time using this technique.
Another similar method of testing involves injecting the allergen directly into the skin. This test is conducted when a person is being tested for allergies to a specific substance like bee venom or any other chemical. These skin tests are used to diagnose allergies to food, mold, animal fur, pollen, penicillin, bee venom, and contact dermatitis.
Intradermal Allergy Test Preparation
To prepare for the test, first give your detailed medical history to the medical practitioner. Discuss your illnesses, eating habits, lifestyle, work, and social conditions. It is recommended that before you take an intradermal allergy test, you should not have consumed any medication that has antihistamines. If you have taken antihistamines before the test, it may show false negative results. Have a discussion with your doctor, who will tell you which medicines you should avoid.
The tests are usually ordered if you suffer from allergic rhinitis, hives, contact dermatitis, and allergies to chemicals. Intradermal tests are never used for testing food allergies because they can show false positive results and the test itself may cause severe allergic reactions. Some people may have positive responses when they are being tested on specific allergens, without having allergic reactions to those substances in their everyday life.