These
tests will help you and your healthcare provider or allergist know what substances cause
your allergy symptoms. Diagnostic tests for allergies may include:
-
Skin
tests. These are the most common allergy tests. Skin tests measure if you have
IgE antibodies to certain allergens such as foods, pollens, or animal dander. A small
amount of allergen is put on the skin. The area is then pricked or scratched. If you
are allergic to the allergen, a small raised bump like a mosquito bite appears after
about 15 minutes. Testing for many allergens may be done at the same time. An
allergist may also do an intradermal test. In this test, you are given a shot
(injection) of a small amount of allergen just under the skin. This type of skin
testing is more sensitive than prick or scratch testing. Skin test results are
available right after the testing is done.
-
Blood
tests. Blood tests for allergies measure IgE antibodies to certain allergens
in the blood. The testing that is most often used is called RAST (radioallergosorbent
test). Or you may have a newer blood test called an ELISA (enzyme-linked
immunosorbent assay). Blood tests may be used when skin tests can't be done. For
example, if you have certain skin conditions or a very recent severe allergic
reaction. A positive blood test does not always mean that you have a specific
allergy. These tests take longer to get results and may cost more than skin
testing.
-
Challenge test. This test is always supervised by an allergist. You eat or
breathe in (inhales) a very small amount of an allergen. Then you are closely watched
for an allergic reaction. Challenge testing is often done to test for food or
medicine allergies when an allergist thinks you have a low risk for reaction.
See your healthcare provider for any positive test result. Your
provider will be able to talk with you about the tests and knows your health history.
