Urea

Urea can be found in urine, skin, and other tissues as a degradation product of proteins. In concentrations below 5%, urea is humectant moisturizing. At concentrations above 10% it is keratolytic, that helps to break away old, flaking, and cracked skin.
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Origin
Urea

Overview

Urea, as the name suggests, can be found in urine, skin, and other tissues as a degradation product of proteins.

As one of the components of the Natural Moisturizing Factor (NMF), urea contributes to the preservation of healthy skin hydration levels. It binds and retains water, but is also easily washed away from the skin’s surface.

Urea in skincare has many different uses. In low concentrations (below 5%) it is humectant moisturizing, replenishes the skin’s NMF, and regulates trans-epidermal water loss. At concentrations above 10% it is keratolytic, meaning that it helps to break away old, flaking, and cracked skin (e.g., on the elbows, soles of the feet, or in people with psoriasis).

One last benefit of urea is that it is a penetration enhancer: it makes it easier for other molecules to pass through the skin barrier.

Science

1
Celleno L. (2018). Topical urea in skincare: A review. Dermatologic therapy, 31(6), e12690.