Allergy skin testing is the gold standard for determining what patients are allergic to and to what degree. This testing is usually performed in the office and has been used for more than 100 years. Skin testing includes scratch tests (typically on the forearm or back), patch tests, and intradermal tests. Skin tests can include up to 50-60 allergens at one time, depending on your medical history. These tests are typically well tolerated but may produce itching in the affected area.