What Happens During the Allergy Skin Test?

The procedure varies depending on what type of allergy skin test you are having. The three main types of skin tests are the scratch test, intradermal test, and the patch test.

• Scratch test (also known as a puncture or prick test). First, a doctor or nurse will examine the skin on your forearm or back and clean it with alcohol. Areas on the skin are then marked with a pen to identify each allergen that will be tested. A drop of extract for each potential allergen -- such as pollen, animal dander, or insect venom -- is placed on the corresponding mark. A small disposable pricking device is then used so the extract can enter into the outer layer of the skin, called the epidermis. The skin prick is not a shot and doesn't cause bleeding.
• Intradermal test. After examining and cleaning the skin, a small amount of the allergen is injected just under the skin, similar to a tuberculosis test.
• Patch test. Another method is to apply an allergen to a patch, which is then placed on the skin. This may be done to pinpoint a trigger of allergic contact dermatitis. If there are allergic antibodies in your system, your skin will become irritated and may itch, much like a mosquito bite. This reaction means you are allergic to that substance.

What Happens During the Allergy Skin Test?