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Allergy Tests Explained

Allergy Testing – Not One Size Fits All

The term “Allergy Testing” is broad, and often a source of confusion for patients. Allergy testing can actually encompass a number of different tests used to diagnose different types of allergies.

There are two main types of allergy tests, skin allergy tests and patch tests. Skin allergy tests are tests used to look for more “internal” types of allergens and to help identify triggers for conditions such as allergic rhinitis, allergic conjunctivitis, allergic bronchial asthma, food allergies, and medication allergies. Patch testing looks for more “external” type allergens and is typically used to help identify the causes of skin rashes.

Skin Prick Allergy Testing

Skin allergy tests can be further broken down into two different types of tests: percutaneous (prick or scratch) tests and intradermal tests. Percutaneous tests are performed by placing (“pricking”) a small amount of allergen into the skin on the point of a small needle. After a brief wait, the testing areas are examined and measured for the presence of redness or swelling that would indicate a positive reaction. Intradermal testing involves a deeper injection of allergens into the skin resulting in a much more sensitive test for allergies that can be used to clarify inconclusive percutaneous results. These tests identify a specific immune response, Type I (Immediate) Hypersensitivity, which is the mechanism of allergy for allergic rhinitis, allergic conjunctivitis, allergic bronchial asthma, and for penicillin drug allergy. Common allergens that are tested for in the manner include ragweed, pollen, dust mites, pet dander, foods, medications, and insect venom.

Patch Allergy Testing

Patch testing tests for a completely different set of allergens and in a different way. For patch testing, small amounts of allergen are placed on a “patch” and taped onto the skin. These are left in place for forty-eight hours, and no needles are used. After the designated time, the patches are removed and the skin is inspected for allergic reactions. These tests identify a different type of allergic response, known as Type IV (Delayed) Type Hypersensitivity, since the reaction is often delayed hours to days after the initial exposure. Patch testing is primarily a tool to identify the trigger of skin rashes, and example allergens identified this way can include fragrances, preservatives, dyes, metal, rubber, and topical medications.

Have you been suffering from potential allergic reactions or skin sensitivities? Come in and let us help identify the source of your allergies. Our goal is to help you navigate the complexities of medicine and to be your one stop for all of your allergy needs. Let us know if we can help!