Sensitive Skin and Skin Barrier

By: Giorgio Dell'Acqua

Posted: November 26, 2008, from the December 2008 issue of Cosmetics & Toiletries.

Sensitive skin usually is described as a skin type showing higher reactivity than normal skin with responses to external factors ranging from itching and dryness to intense inflammatory reactions such as erythema or rash. This reactivity may vary according to seasonal changes. Anatomical modifications include a higher sensorial response, an enhanced immune responsiveness and diminished skin barrier function.

Individuals with sensitive skin can exhibit a predisposition to skin barrier damage due to external factors such as detergents, and they have a tendency to hyperreact to topical agents. When skin biophysical parameters such as transepidermal water loss (TEWL), hydration, pH, sebum and colorimetric red color (an indication of erythema) are measured in individuals with sensitive skin, the values for TEWL, pH and colorimetric red value usually score higher, while values for hydration and sebum score lower as compared with non-sensitive skin individuals. What is of particular interest is that in sensitive skin, only the values related to hydration and colorimetric red color show statistical differences. This suggests a primary role for the skin barrier and its related permeability to trigger sensitive skin, since skin barrier impairment will increase irritant adsorption. The increase in erythema parameters due to increased vasodilation would be identified as a secondary influence due to increased irritant adsorption; i.e., the so called outside-inside theory. Since atopic dermatitis, or atopic dry skin in cosmetic terms, is also characterized by increased skin barrier permeability and erythema development, similarities arise between sensitive skin and atopic dermatitis—the latter being the extreme condition for sensitive skin.

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