[Urea : properties, effects, use].

If urea, a physiologic substance, is applied locally, it has a favorable effect on the skin, it keeps the horny layer moist. However, high concentrations might impair the functions of the skin, for urea penetrates easily into the skin, exerts mucolytic and keratolytic effects, changes the keratin structure, and promotes just like dimethylsulfoxide, the permeation and the resorption of active ingredients. Moreover, urea causes a thinning of the epidermis by influencing the epidermal prolifertion. The properties of urea are of considerable interest in dermatotherapy. However, high concentrations of urea should only be applied for long periods of time, and on large surfaces of the skin, for instance in the treatment of dry skin, in the form of cosmetics, under medical supervision.