Although the pathogenesis of sensitive skin syndrome is not completely understood, the most accepted theory is the presence of an altered barrier function. Irritation results from the abnormal penetration of substances to deeper layers of the skin, where they can induce vasodilation and stimulate c-type neuronal fibers. Also, changes in the pH of the stratum corneum have been found to induce skin sensitivity through the activation of the transient potential receptor vanilloid (TRPV) neuronal receptors.