There are two primary ways to confirm allergies: skin tests and blood tests. People with allergy symptoms, such as the runny nose of (hay fever, may think they have the symptoms of a cold, but often the symptoms continue absent from other associated cold symptoms. Testing is the definitive way to determine allergies.


A skin test is usually performed by an allergist, a doctor specializing in allergies. The skin test is used to determine whether a person has IgE antibodies in the skin that react to a specific allergen. IGE (short for immunoglobulin) antibodies are the substances made by the body that, when they encounter a specific allergen, help produce histamine and/or other substances. Histamine in the nose and eyes, for example, produces symptoms like the itchy nose or watery eyes one may suspect is from an allergy. In the lungs, histamine reduces and constricts the airways; in the skin, it can cause rashes.

The test is administered to the skin with tiny weakened extracts from suspected allergens (pollen, mold, dust mites), either injected under the skin or applied via a small scratch or puncture made on the arm or back. A positive test will produce a small reddened area, called a wheal (hive), with a surrounding flush, called a flare. Although such a reaction indicates that IgE antibody to a specific allergen is present, respiratory symptoms do not necessarily result.


Skin testing is the most sensitive and least costly way to identify allergies. People with widespread skin conditions like eczema, however, should be tested via a blood test. A fairly common blood test is the radio-allergosorbent test (RAST), which can be performed when eczema is present or if a person has taken medicines that interfere with skin testing. |

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