Skin Testing for Allergies
How do allergy skin tests work?
Skin test or scratch test is an easy and quick way to determine if someone has an allergy. The test is performed on the back or the forearm. During the skin test, a drop of allergen is pricked on the surface of the skin. 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. 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.