Dr. Donald Levy, Allergy, Asthma, and Immunology, Orange County Ca

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Facts on Allergy Testing

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Office Location
705 W. La Veta Ave.
Suite 101
Orange, CA 92868
(714) 639-7847



Facts on Allergy Testing

Allergy testing can help the more than 50 million Americans who have allergies find out what makes them sneeze and wheeze and help their allergist develop the most effective treatment plan.

Allergy tests are performed using either skin tests or blood tests.

There are two types of skin tests: percutaneous, also known as prick-puncture or scratch tests, and intracutaneous, also known as intradermal, tests. Skin test results are obtained quickly, with positive reactions usually appearing in 15 to 30 minutes.

The prick-puncture or scratch test pricks or scratches the surface of the skin with a drop of a suspected allergen. The test is performed on a patient's back or forearm with multiple allergens tested at once. A positive reaction causes redness and swelling to appear at the site of the scratch.

Intracutaneous skin tests are usually performed if prick-puncture test results are inconclusive. This test type involves injecting the suspected allergen extract under the first few layers of skin with a syringe and a very fine needle. Intracutaneous skin tests are more sensitive, and more often positive, than prick-puncture testing, which also means that it more often yields false positive results.

Blood tests, known as radioallergensorbent testing (RAST) or other newer blood tests, such as ImmunoCAP, often are used to test for allergies when: a physician advises against the discontinuation of medications that can interfere with test results
or cause medical complications; a patient suffers from severe skin conditions such as widespread eczema or psoriasis; or a patient has such a high sensitivity level to suspected allergens that any exposure to those allergens could result in potentially serious side effects.

Blood tests are conducted by drawing a blood sample to be sent to a laboratory, which analyzes the sample for the presence of antibodies to specific allergens. It can take up to several days to receive test results.

Children and adults of all ages can be tested for allergies. However, the appropriate testing method should be determined for very young and very old patients based on individual medical history.

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