A test applied to the skin to look for causes of skin rashes.

If your doctor decides that the rash you are experiencing may be due to a substance that you have come into contact with on your skin, they may decide to perform a patch test. The test is different from a typical allergy skin test in that it does not predict allergies to inhaled substances such as pollen, mold, animal dander, etc. The test also will not predict the likelihood of an anaphylactic reaction to substances such as foods, insect stings, etc. (See also Anaphylaxis). This test is typically applied to your back in the doctor's office, and will be removed when you return for your initial reading 48 hours later. The test site should remain clean and dry, and your back may require shaving prior to placement of the materials. You should avoid sunburn and steroid creams to your back prior to patch testing, as these may interfere with the results.

What is allergic contact dermatitis?

This is a skin reaction that occurs when you touch or contact substances that you are allergic to.Your skin can be itchy, cracked, red, sore, and even bleed. The substances that cause this reaction can be an ingredient in your makeup, aftershave, shampoo, jewelry, medication, and clothing.You may also find these substances at work in your cleaning supplies, paper and ink, medicines, disinfectants, construction materials and rubber products.