Allergy Testing
If you have an allergy, your body is reacting to something you inhaled, touched or ate. The substances that trigger an allergic reaction are called allergens (ie. food, pollen, mold, dust mites, insect stings, animal dander, etc.). Reactions to these allergens range from annoying to life-threatening.
Skin Test
Here at Hill Country Allergy & Asthma we determine your degree of allergy through a procedure
called skin testing where the prick test and the intradermal (under the skin) test are used. With each
test, you will be exposed to small amounts of things to which you may be allergic (medications, insect venom, molds, pollens, animal dander, dust mites, foods, etc.). If you are allergic
to a substance a reaction will appear which looks like a mosquito bite. The staff will
examine any reaction that appears to decide whether a positive reaction has occurred indicating
allergy.
In the prick test, allergens are applied by tiny pokes that penetrate only the very top layer of skin.
These pokes will rarely draw blood. You feel only a slight prick or scraping of the skin. Reactions are
usually seen in ten to thirty minutes if they are going to occur, and you generally won’t have any
other symptoms besides the small hives where the tests were done, which go away typically within a few days.
The intradermal test involves the injection of a small amount of allergen placed with a needle just
under the skin. This pushes the skin up slightly, producing a round whitish, raised area called a
wheal. This procedure is not as painful as the usual injection, because only a small amount of
allergen is injected and the small needle slips barely under the skin surface. Any reaction usually
occurs within ten to twenty minutes.
The prick method has the advantage of letting the provider test a large number of allergens at one
time. Intradermals are used as a confirmatory test. The provider will decide whether to use one or
both methods for the testing. A MULTI-TEST is a sterile disposable, multiple test head applicator
used to administer skin test substances. It provides a quick, convenient, and standardized procedure
and is frequently used for children. There are eight tests heads on each device.
Skin testing is the most common and is least invasive. If you are allergic to ragweed pollen
but not to cats, only the ragweed allergen will cause a little swelling or itching. The spot where the
cat allergen was applied will remain normal.
*A skin test has to be done in an allergist’s office to minimize the risk of rare side effects and reactions to tests.
Challenge Tests
In a challenge test, a very small amount of an allergen is inhaled or taken by mouth. Challenges are
done mostly with potential food or medication allergies, and it is very important that they be
supervised by an allergist.
Blood Tests
This test involves drawing blood, so results are not available as rapidly as with skin tests. Blood tests
are more limited and are generally used when skin tests might be unsafe or won’t work, such as if
you are taking certain medications, or have a skin condition that may interfere with skin testing.
