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.
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. As such, in psoriasis, urea can directly affect the rapid proliferating skin cells (keratinocytes) and has a water binding capacity, which results in a moisturising effect2. 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, including psoriasis, water loss from the upper skin layer is linked to a reduced skin barrier function, which may be worsen the disease symptoms4. Recently, urea has been suggested also to influence the expression of genes involved in a proper skin barrier function and antimicrobial defense5. In a number of other skin conditions topical application of urea has also proved effective in reducing severity2.
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