A skin prick test, also called a puncture or scratch test, checks for immediate allergic reactions to as many as 200 different substances at once.
This test is usually done to identify allergies to pollen, mold, pet dander, dust mites and foods. In adults, the test is usually done on the forearm. Allergy skin tests are not painful. This type of testing uses needles (lancets) that barely penetrate the skin's surface.
After cleaning the test site with alcohol, the nurse draws small marks on your skin and applies a drop of allergen extract next to each mark. He or she then uses a lancet to prick the extracts into the skin's surface. About 15 minutes after the skin pricks, the nurse observes your skin for signs of allergic reactions.
If you are allergic to one of the substances tested, you'll develop a raised, red, itchy bump (wheal) that may look like a mosquito bite. The nurse will then measure the bump's size and record the results. Next, he or she will clean your skin with alcohol to remove the marks.