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.