What evidence is there for moisturisers?

Before reading on, think about how this article may help you to do your job better. Given the widespread use of moisturisers there are surprisingly few good quality studies of efficacy in patients. Some studies show that some of the more common ingredients used do increase skin hydration or improve the barrier function of the skin (ie, reduce transepidermal water loss; TEWL). However, even where studies exist, one of the problems for investigators is the lack of a standardised definition of dry skin that can be measured objectively. In addition, studies tend to be small — often with around 30 subjects. Many studies use changes or differences in TEWL or capacitance as measures of effectiveness, but changes in symptom scores are often a better indicator. TEWL is not a sensitive measure and has been shown to either increase or decrease after the application of various moisturisers. Indeed, improvement in symptoms does not always correlate with a reduction in TEWL. Some studies in people with xerotic skin have included visual analogue scales and expert assessment in addition to the biometric methods as part of the evaluation process.