contact dermatitis, a skin rash resulting from exposure to a primary irritant or to a sensitizing antigen. In the first, or nonallergic, type, a primary irritant, such as an alkaline detergent or an acid, causes a lesion similar to a thermal burn. Emergency treatment is to drench liberally and immediately with water. In the second, or allergic, type, sensitizing antigens cause an immunological change in certain lymphocytes. Subsequent exposure to the antigen causes the lymphocytes to release irritating chemicals, leading to inflammation, edema, and vesiculation. Poison ivy and nickel dermatitis are common examples of this type of delayed hypersensitivity reaction. The diagnosis can be aided by patch testing with suspected antigens. Treatment includes avoidance of the irritant or sensitizer, administration of topical corticosteroid preparations, and use of soothing or drying lotions. In severe cases, systemic corticosteroids may be used. Also called dermatitis venenata. Compare atopic dermatitis. See also hypersensitivity reaction. ▪ OBSERVATIONS: Contact dermatitis is caused by contact with irritants and manifests as skin irritation at the site of contact. This irritation can vary from transient redness to bulla formation. Itching is common, and weeping and crusting may be present. Diagnosis is made through clinical evaluation, detailed history to locate possible source of contact rash, and patch testing to isolate allergens. ▪ INTERVENTIONS: Removal of irritant from the skin with soap and water is the first line of treatment. Treatment then focuses on alleviating the itching and rash. Cool, wet cloths are effective for treating blistering. Oral antihistamines and colloidal oatmeal baths are used to control itching. Erythema may be treated with topical steroids. Oral corticosteroids are reserved for severe or widespread dermatitis. ▪ PATIENT CARE CONSIDERATIONS: Subsequent exposure to the antigen causes the lymphocytes to release irritating chemicals, leading to inflammation, edema, and vesiculation. Poison ivy and nickel dermatitis are common examples of this type of delayed hypersensitivity reaction.
