skin disorders
Contact Dermatitis
Diagnosis of Contact Dermatitis
A doctor's evaluation and the person's history Sometimes patch testing Determining the cause of contact dermatitis is not always easy. The person's occupation, hobbies, household duties, travel, clothing, use of products applied to the skin, cosmetics, and household members' activities must be considered. Most people are unaware of all the substances that touch their skin. Often, the location and pattern of the initial rash provide an important clue, particularly if the rash occurs under an item of clothing or jewelry or only in areas exposed to sunlight. However, many substances that people touch with their hands are unknowingly transferred to the face, where the more sensitive facial skin may react even if the hands do not. If a doctor suspects contact dermatitis but the cause is not apparent, Skin Tests can be done to help identify the substance (allergen) that is causing the allergic reaction. For this test, small patches containing standard contact allergens are placed on the skin of the upper back and left on for 48 hours to see whether a rash develops beneath one of them. After 48 hours, they are removed, and the doctor evaluates the skin underneath. The skin is evaluated again a day or two later. 