What Is Skin Testing for Allergies?
What is skin testing for allergies?
The most common way to test for allergies is on the skin, usually the forearm or the back. To do a typical skin test (also called a scratch test), an allergist (a doctor who diagnoses and treats asthma, allergies, or immune system conditions) or nurse will put a tiny bit of an allergen (such as pollen or food) on the skin, then prick the outer layer of skin or make a small scratch on the skin.
The allergist may repeat this, testing for several allergens in one visit. This can be a little uncomfortable, but isn't painful.
If a child reacts to one of the allergens, the skin will swell a little in that area. The doctor can see if a reaction happens within about 15 minutes. The swelling usually goes down within about 30 minutes to a few hours. Other types of skin testing include injecting allergens into the skin or taping allergens to the skin for 48 hours.
With a skin test, an allergist can check for these kinds of allergies:
- environmental, such as mold, pet dander, or tree pollen
- food, such as peanuts or eggs
- medicines, such as penicillin
Some medicines (such as antihistamines) can affect skin testing. So check with the doctor to see if your child should stop taking any medicines before the test. While skin testing is useful and helpful, sometimes doctors must do more tests (like blood tests or food challenges) to see if a child is truly allergic to something.
Skin tests are usually well tolerated. Rarely, they can cause a more serious allergic reaction. This is why skin testing must always be done in an allergist's office, where the doctor is prepared to handle a reaction.