Non-invasive assessment of urea efficacy: A review.

Urea is an emollient widely used in clinical dermatology to moisturise and protect the skin. Non-invasive techniques can be useful in evaluating and quantifying the moisturising and hydrating properties of topically applied urea. Amongst these, transepidermal water loss, skin conductance and capacitance are the most widely used. Dynamic tests and mapping of skin moisturisation are additional features that can be used to evaluate the dynamics of water into the stratum corneum. Ultrasound and mechanical properties can be used to investigate the effects on skin smoothness and tone. In conclusion, urea is a fundamental ingredient of cosmetic and dermatological formulations and can have several positive effects on skin function. These can be easily investigated and monitored using non-invasive techniques measuring the stratum corneum function.