Dithranol (anthralin) is one of the basic compounds used in the treatment of psoriasis vulgaris. However, in outpatients its use is largely restricted as it may cause discoloration of skin, clothes, and bedding as well as significant skin irritation. The combination of dithranol with urea results in a better benefit/side-effect ratio. Even at relatively low dithranol concentrations (0.1%/0.2%) combined preparations have been found to be effective over several weeks of application. The therapeutic results of such treatment are comparable to those of topical glucocorticosteroid preparations.