Urea is an important component of the outer skin layers, that serves to keep healthy skin hydrated by attracting and binding water as a part of the skin’s natural moisturising factor1. In dry skin conditions, water loss from the upper skin layer is linked to a reduced skin barrier function, which may worsen disease symptoms. Urea has both emollient (moisturising) and keratolytic (scale diminishing) properties, which means it can be used to help both dry and scaly skin.
In the dry-skin related disease, psoriasis, topical urea has been shown to increase water content in the skin, and reduce the loss of water across the skin surface when measured shortly after application2. A concentration of urea of 10% has also been shown to reduce scaling and redness of psoriatic plaques when compared to the same ointment without urea3. These different properties are likely dependent on the concentration of urea in the product.
In concentrations above 10%, urea can help break down the outer layer of the skin and reduce scale thickness. In concentrations below 10% urea functions primarily by attracting and retaining water which helps moisturise the upper skin layers. In dry skin conditions, water loss from the upper skin layer is linked to a reduced skin barrier function, which may worsen the disease symptoms4. Recently, urea has been suggested also to influence the expression of genes involved in the proper skin barrier function and antimicrobial defense5.
The concentration of an ingredient is important for its efficacy, and therefore products containing the same ingredient may not necessarily have the same effect as in the studies mentioned above.
Updated: July 2017