How do allergy skin tests work?

There are two types of skin tests. During the first type of skin test, a drop of a suspected allergen is pricked on the surface of the skin. The test is performed on the back or forearm. Many suspected allergens are tested at the same time. If you are allergic to one of the tests, you will have redness and swelling at the test spot.

How long does it take to get skin test results?

Skin testing is fast. For both types of skin tests, positive reactions usually appear within 20 minutes. Sometimes redness and swelling can occur several hours after skin testing. The delayed reaction usually disappears in 24 to 48 hours, but should be reported to the allergy doctor or nurse.

Is skin testing painful?

Both types of skin tests have little or no pain. However, positive reactions cause annoying itching red bumps which look and feel like mosquito bites. The itching and bumps are gone usually in just a few short minutes or hours. Your allergist may apply a cream to your skin to help decrease the reaction, or have you take an antihistamine afterwards.

 

Does medicine interfere with allergy skin tests?

Some medicines do interfere with allergy skin tests. The allergist will tell you if you have to change your medicine before allergy skin testing.