Urea is a derivative of proteins. It is a white crystalline powder with a slight ammoniacal odor. Urea is best solubilized in water, one gram dissolves in 1 mL water, 10 mL 95% alcohol, or 2 mL glycerol.
Urea moisturizes the skin, smooths, and relieves itching. As one of the most critical soluble substances of the stratum corneum, it is of increasing importance in dermatological therapy and cosmetics. A lack of urea, a natural moisturizing factor (NMF), identifies diseases such as atopic dermatitis or clinically dry skin. Normal skin contains about 1 % urea.
This NMF improves the skin's water retention ability, revealing a smoother, supple, and youthful appearance. In addition, urea may act as a mild keratolytic agent with higher concentrations, eliminating old and dead cells from the skin surface. Furthermore, in complex formulations, it enhances the penetration of other ingredients, boosting effectiveness.
Urea is an excellent moisturizer & humectant, that replenishes natural urea content in the skin after cleansing (avoids dryness), has keratolytic properties (skin-exfoliating), and antiseptic & deodorizing effects. It is used in a final concentration of 5-15% in creams, lotions, sun care products, after-sun lotions, abrasive creams, and cleansing products including shampoos & body washes.
What's the urea role in cosmetics?
Urea is one of the essential NMFs (natural moisturizing factor) in the skin, and deficiency may lead to dry skin or even atopic dermatitis. Some surfactants such as sodium lauryl sulfate in makeup removers, foaming, and other cleansers can wash out the urea from the epidermis, dramatically decreasing amounts of essential NMF, water-binding ability, and during the skin. In vivo, tests showed that urea-supplemented cleaners compensate for the drying effects of surfactants and increase urea amounts in the skin. Furthermore, a lack of water-retaining substances may be reimbursed in dry skin by prolonged topical application of urea-containing skincare products such as serums, masks, and creams.