Urea (0.05 %)
Urea (also called Carbamide) is a naturally occurring compound found in the skin and classified as a natural moisturizing factor (NMF), making up approximately 7% of NMFs. It functions as both a moisturizer/humectant and a mild keratolytic agent, capable of breaking down bonds in the protein filaggrin to free up amino acids in the skin. It is considered a skin-identical ingredient and is used across a wide range of concentrations (from low percentages in general moisturizers to 10–40% in therapeutic formulations).
Urea helps the skin retain water, keeping it plump, elastic, and hydrated. It enhances antimicrobial peptide expression and improves skin barrier function. At higher concentrations (10–40%), it has demonstrated effectiveness in skin disorders associated with excessive dryness and impaired barrier function, such as ichthyosis, xerosis, psoriasis, eczema, and seborrheic dermatitis.
At high concentrations (10–40%), urea acts as a keratolytic and should be used with appropriate guidance; no specific contraindications are noted in the source for low-concentration cosmetic use.
