An emollient forms a thin, oily layer over the skin to prevent loss of water from damaged and diseased areas. The water trapped in the stratum corneum passes into the corneocytes, which swell and close-up intercellular gaps. In addition, emollients, especially those formulated with ceramides (lipid molecules), can penetrate deep into the stratum corneum and restore the barrier effects of the deficient lipids. 

Humectant-containing emollients attract additional water into the skin from the dermis – the middle layer of skin. Commonly used humectants include urea, glycerine and sodium pyrrolidone carboxylate. Emollients should be prescribed in sufficient quantities to allow for frequent, regular applications. 

Some dermatologists recommend allowing patients to find the emollients that they like best – smell and feel can be important, especially to children. Simple occlusive emollients, which form a protective layer over the skin, are short-lasting and need to be applied frequently – typically three to four times per day. Humectant-containing emollients last longer and may only need twice-daily application. When advising patients on which emollients to try, it is important to ensure that they have at least one of each type and not just three or four simple occlusive emollients.

Emollient wash products should be used in preference to soaps and detergents (e.g. shower gel). Some emollient creams and lotions that have oil-in-water formulations can be used for washing. For young children, one product can sometimes be used for both leave-on moisturising and washing.