Urea is an important component of the epidermis where it serves to keep healthy skin hydrated by attracting and binding water as a part of the skin’s natural moisturising factor .
In dry skin conditions, including psoriasis, water loss from the upper skin layer is linked to a reduced skin barrier function, which may be worsening the disease symptoms .
In psoriasis, topical urea has been shown to increase epidermal water content and reduce the loss of water across the skin surface when measured shortly after application .
+ Urea has both emollient (moisturising) and keratolytic (scale diminishing) properties, which means it can be used to help both dry and scaly skin
- It may cause mild local irritation, and stinging sensation particularly in high concentrations
What is the optimal concentration of urea?
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 urea . As such, in psoriasis urea can directly affect the rapid proliferating skin cells (keratinocytes) and has a water binding capacity, which results in a moisturizing effect .
These different properties are likely dependent on the concentration of urea in the product. In concentrations > 10%, urea can help break down the outer layer of the skin and reduce scale thickness. In concentrations <10% urea functions primarily by attracting and retaining water which helps moisturise the upper skin layers.
What else do we know about urea?
Recently, urea has been suggested also to influence the expression of genes involved in the proper skin barrier function and antimicrobial defense . In a number of other skin conditions topical application of urea has also been shown effective .
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