Allergy Skin Testing
Skin Prick Testing
This type of testing is the most common and is relatively painless. A very small amount of certain allergens is put into your skin by making a small indentation or “prick” on the surface of your skin.
If you have allergies, just a little swelling that looks and feels like a mosquito bite will occur where the allergen(s) to which you are allergic was introduced. 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.
You don’t have to wait long to find out what is triggering your allergies. Reactions occur within about 20 minutes. And you generally won’t have any other symptoms besides the small hives where the tests were done, which go away within 30 minutes. If your prick skin tests are negative but your physician still suspects you might have allergies, more sensitive “intradermal” tests may be used in which a small amount of allergen is injected within the skin.
Skin tests are best performed in an allergist’s office to assure the test results are read properly and to minimize the risk of rare side effects.
When you have intradermal skin testing done, a small amount of each thing you may be allergic to (allergen) is injected under the skin. If you are allergic to an allergen, you will get a bump and redness where the allergen was injected. After a short time, each skin test reaction is measured for swelling and redness. A large enough skin reaction is a positive skin test. This means an allergy may exist to the allergen placed at that site. Your doctor will compare your skin test results with your history of symptoms.