What Is the Procedure for Testing for Allergies?

An allergy is when the body’s immune system sees a substance as a harmful “invader” and overreacts to it. Allergens are substances that trigger an immune response, called an allergic reaction.  

Allergy testing helps figure out if you are allergic to things you eat, touch, or inhale. Allergists are doctors who specialize in diagnosing and treating allergies and they can determine which test will best detect the allergens causing a person’s symptoms. 

Skin tests are the most accurate, though blood tests may also be used, to help determine a patient’s reaction to common allergens such as plant pollens, animal dander, dust mites, molds, insect stings; certain foods such as peanuts, shellfish, wheat, eggs, and dairy; and some medications, such as penicillin.

Skin tests for allergies are done in an allergist’s office. Prior to the test, tell your doctor about any medicines you take, both prescription and over-the-counter, because some medications may interfere with skin testing.

There are two main types of skin testing for allergies and results are available quickly: 

• Prick or scratch test (also called a percutaneous test)
  • The most common type of skin testing for allergies
  • A tiny drop of a potential allergen is pricked or scratched into the skin
  • Several different allergens are tested
  • The procedure takes about 5 to 10 minutes to place allergens on the skin
    • Allergens are usually placed on the forearm in adults and on the back in children
  • After about 15 minutes the skin is examined to check for a small red lump where any of the allergens were placed
• Intradermal test
  • This test is used to check if a person is allergic to things such as insect stings and penicillin
  • A small amount of the allergen is injected under the skin through a thin needle

What to Expect

• Both the prick test, scratch test, and intradermal test may hurt a little and the skin may itch or swell slightly in areas where the allergen was placed if you are sensitive to it. Very rarely, a more serious allergic reaction could occur and patients are monitored throughout the exposure. 
• The procedure for blood testing for allergies involves a single blood draw with a needle, however, it may take several days to get results. Blood may be drawn at a doctor’s office or at a lab. Patients may experience some minor pain, bleeding, or bruising where the needle is placed.