Surfactant equilibria and its impact on penetration into stratum corneum

Anionic surfactant penetration into the skin and their subsequent interactions with stratum corneum lipids and proteins has historically been linked with irritation and dryness from the use of soaps, body washes, facial cleansers, shampoos, and other rinse-off personal care products. Mechanisms of surfactant penetration into the skin surface has been a topic of debate for decades. In this review, we discuss relevant theories of surfactant penetration into skin as well as interactions of surfactants with skin components. We present evidence that thermodynamic analyses of surfactant solution equilibria can be useful in modeling these behaviors. A theory of surfactant monomer penetration into stratum corneum is proposed.