Allergic contact dermatitis is a common skin rash that looks like eczema. It occurs when a person becomes allergic to chemicals found in soaps, shampoos, lotions, hair dye, make up, sunscreens, aftershave, deodorant, laundry detergent, as well as certain materials such as metal, rubber products, acrylic materials (nail products), fabric dyes, and adhesives. It is also possible to become allergic to topical medications such as topical antibiotics, topical steroids, and topical antifungal creams. Often patients think they can’t have contact dermatitis because they have been using the same products for years. However, it is more common to become allergic to a chemical in a product that has been used for a long period of time rather than something new.
Allergic contact dermatitis is diagnosed by patch testing to common allergens. Allergens are applied to a patient’s back in panels that will stay in place for two to three days. These panels are removed after the two-three-day period and the test is read on the 4th or 5th day from when the patches were placed. It is important to keep the back dry for the whole five-day period and therefore it is not possible to shower until patch testing is complete.
Contact dermatitis is a delayed immune reaction involving a different branch of the immune system than the type of allergic reaction that occurs with allergies from pollen, animal dander, or food. Contact dermatitis can only be diagnosed by patch testing. Environmental allergies to pollen, mold, animal dander, and food allergies are diagnosed by a different type of testing called skin prick testing.
For patients who suffer from contact dermatitis, once the offending allergen is identified by patch testing, the patient should stop using all products that contain the allergen. We have informational handouts about each allergen and we utilize a database that will provide a list of products, tailored for each individual patient, which are safe to use. We strongly recommend that patch testing be considered for anyone suffering from severe eczema. Patch testing should be done before starting strong eczema therapy such as injected biologic medications and a new class of medication called jak inhibitors. Once allergens are identified and avoided, the allergic contact dermatitis should resolve. Some patients will have both eczema and allergic contact dermatitis. If this is the case, eczema control will also improve when allergens are avoided.