Simply put, dermatitis is inflammation of the dermis. Allergic contact dermatitis, eczema (atopic dermatitis), and seborrheic dermatitis are three types of dermatitis, which each have different causes and symptoms.
Allergic contact dermatitis is caused by reactions to allergens that come into contact with your skin. Allergens can be determined by a patch test administered to the skin, but some common allergens include rubber, nickel, hair dyes, some skin care products, poison ivy/poison oak, chromates, and neomycin. People with mild rashes from allergic contact dermatitis can usually treat the rash effectively with a topical steroid cream (Cortisone) or antihistamine (Benadryl). Other treatment methods are available for severe rashes. In general, people with allergic contact dermatitis should avoid the allergen once identified.