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Allergic & Contact Dermatology Services

NYU Langone dermatologists have extensive experience and expertise in diagnosing contact dermatitis, a form of skin inflammation that results from direct contact of a substance with the skin’s surface. Contact dermatitis often appears as a red, scaly rash and occasionally as blisters, crusting, and swelling. It can cause the skin to be itchy and even painful.

There are two types of contact dermatitis: irritant and allergic. Irritant contact dermatitis, the most common form, typically occurs after exposure to chemicals that irritate the skin. Allergic contact dermatitis occurs when a substance triggers an allergic immune response. Substances that commonly cause allergic contact dermatitis include metals, fragrances, plants, dyes, preservatives, latex and synthetic rubber, and other chemicals found in everyday items. Our doctors partner with you to understand your symptoms, review your detailed medical history, and examine your skin for signs of contact dermatitis.

Patch Testing for Allergic Contact Dermatitis

If our dermatologists suspect that allergic contact dermatitis is causing a rash, a patch test is the most effective diagnostic tool. NYU Langone dermatologists have been leading experts in the technique of patch testing since the 1930s, when the patch test was first brought to the United States. This allergy test is uniquely designed to identify the cause of contact dermatitis without the use of needles.

The patch testing process typically occurs over three to seven days, and requires at least three visits with your dermatologist. In the patch test, a number of thin metal or flexible plastic chambers that contain a small amount of an allergen are applied to the back. The patch tests are removed after two days, at which point the skin is examined for evidence of irritation.

You return to your doctor’s office after a day or more for a final reading, during which our doctors examine the skin for signs of allergic reactions. The allergens used in the test are found in everyday products as well as more unusual sources, and help distinguish which products or other exposures may be causing the rash. Once the patch testing process has concluded, patients are provided with a list of products to use that do not contain the chemicals that caused the reaction.