Contact dermatitis for primary care providers.

Contact dermatitis is an eczematous dermatitis developing at a site where the skin has been in direct contact with the cutaneous irritant or allergen from the environment. Irritant contact dermatitis (ICD) is the most common form. Allergic contact dermatitis (ACD) is inflammation of the skin caused by an antigen that elicits a type IV hypersensitivity reaction. Clinical evaluation and judgment are a critical part of the process. Patch testing in an objective method to aid in differentiating ACD from ICD and of verifying responsible allergens.