Allergic contact dermatitis occurs when your skin comes in direct contact with an allergen. When you come in contact with poison sumac, poison oak or poison ivy it causes an allergic contact dermatitis. An oily coating, which covers these plants, causes red itchy rash. An individual can have an allergic reaction from actually touching the plants, or simply by touching clothing, pets or gardening tools which have been in contact with this oil. Come to Reforma Dermatology to control your symptoms.