Epaderm ointment doesn't contain any active ingredients as such. It is a mixture of yellow soft paraffin, liquid paraffin and emulsifying wax that produces a greasy moisturiser. It works by providing a layer of oil on the surface of the skin to prevent water evaporating from the skin surface.
Moisturisers are helpful for dry skin conditions, particularly eczema and dermatitis, which get worse when the skin is allowed to dry out. Used regularly they help restore the skin's smoothness, softness and flexibility by helping the skin retain moisture. They should be applied frequently to prevent the skin drying out.