The deterioration of the skin barrier observed in cases of xerosis results from internal and external factors that disrupt the skin's hydrolipidic balance. The first factor is age. Indeed, over time, the production of ceramides, cholesterol, and fatty acids, essential components of the intercellular cement, decreases. This scarcity weakens the cohesion of the corneocytes, making the skin more permeable to water evaporation. Simultaneously, sebum secretion slows down, which weakens the hydrolipidic film.
Environmental conditions also play a significant role. A cold and dry air, whether in winter or due to inappropriate air conditioning, accelerates water loss by disrupting the lipid structure of the stratum corneum. Additionally, wind and exposure to UV rays damage epidermal lipids, particularly polyunsaturated fatty acids, leading to a degradation of the barrier function and a reduced ability of the skin to retain moisture.
Finally, certain daily habits can exacerbate xerosis, or dry skin. The overly hot showers dissolve the protective lipids of the hydrolipidic film, making the skin more vulnerable to external aggressions. The use of certain soaps, particularly those containing sulfates like sodium lauryl sulfate (SLS), further damages the skin barrier by eliminating epidermal lipids and altering the skin's pH, which weakens the enzymes involved in the maturation of cells in the stratum corneum, or outermost layer of the skin.