If you want to avoid an allergic reaction, it helps to know what you're allergic to. Skin testing is a safe and fairly easy way for your doctor to try to figure out or confirm what's causing your symptoms.
Skin tests use extracts -- a concentrated liquid form -- of common allergens like pollen, mold, dust mites, animal dander, and foods. Once the allergen gets in your skin, it could trigger a rash. Your skin will get irritated and may itch, like a mosquito bite.
That reaction is how the doctor can tell you're allergic to a substance. When you have an allergy, your immune system will make antibodies and set off chemicals to fight the unwelcome invader.
The steps vary depending on what type of test you're having. There are three main ways to get allergens to react with your skin.
Scratch test, also known as a puncture or prick test: First, your doctor or nurse will look at the skin on your forearm or back and clean it with alcohol. They'll mark and label areas on your skin with a pen. Then they'll place a drop of a potential allergen on each of those spots. Next, they'll prick the outer layer of your skin to let the allergen in. (It's not a shot, and it won't make you bleed.)