Hydration and plasticity following long-term use of a moisturizer: a single-blind study.

Skin hydration is thought to have an influence on skin plasticity, and moisturizers have therefore gained widespread use. However, the effects of long-term moisturizer use on the mechanical properties and the long-term correlation between plasticity and hydration of human skin in vivo remain unknown. Nineteen healthy volunteers applied a moisturizer to the volar surface of their forearms for 3 weeks, once daily on one arm and twice daily on the other. The skin capacitance, distensibility, hysteresis and elasticity were measured in both treated areas and in an untreated regional control area. Measurements were carried out at baseline, at one-week intervals during the trial and one week after the termination. Data were assessed in a single-blind fashion. No change was found in any of the mechanical parameters in the moisturizer-treated skin compared to the control. The capacitance of skin was found to increase independently of dose. One week after termination of the treatment, the skin capacitance remained increased. No dose-response effect was seen, however. Long-term use of moisturizers increases skin capacitance significantly, but does not change the mechanical properties. In vivo skin hydration is a poor predictor of skin mechanics.