Emollients

Throughout human history it is possible to find references to the use of emollients. Ancient Egyptians used sesame, almond and olive oils to anoint their skin and to care for the wigs that were fashionable at the time. Natural oils were also used to perfume these. Cleopatra famously bathed in asses’ milk believing that it would be good for her skin. Lanolin, extracted from sheep wool, was widely used as an emollient in medieval Europe. In 1872 a patent was filed for ‘Vaseline’, a product which 140 years later is still immensely successful. Today there are a myriad of cosmetic emollients available, all making various claims towards creating or maintaining youthful looks in the user. The choice of medicinal emollients is also extensive. The British National Formulary lists at least 34 topical emollient products (this does not include the bath oils), which can make selecting a suitable product something of a challenge (British Medical Association and Royal Pharmaceutical Society of Great Britain, 2007) (see Appendix 3 for list of emollients). This section will explore what emollients are and how they work, it will also provide some practical guidance for selecting and using emollients to ensure that they are being used to best therapeutic effect.

Definition
A standard definition for emollients is not widely available, although they are commonly referred to as substances that ‘…reduce the signs and symptoms of dry, scaly skin, making the rough surface soft and smooth’ (Kligman, 2000). This definition does not, perhaps, do justice to the complex nature of emollients. Not only are modern day formulations complex, but their effects are numerous and generally not entirely understood (Marks, 2001). Their usefulness is well recognised by those who work in the field of dermatology; however, there is little good science to back up how they should be used, although increasingly scientific attention is being given to how they work.

Often the words moisturiser and emollient are used synonymously. The British National Formulary makes no distinction between the two. However, some sources do differentiate between an emollient and a moisturiser; these differences are discussed here.

The New Zealand online dermatology resource, Dermnet NZ, refers to an emollient as a substance that softens the skin and a moisturiser as one which adds moisture (www.dermnet.nz). Voegeli (2007) suggests that the following distinctions should be made:

• Emollients are lipids that occlude the skin surface thus preventing water loss from the stratum corneum.
• Moisturisers are lipid emulsions that actively hydrate the skin by the application of a humectant to the skin surface (often glycol or urea). Humectants are water loving and draw water from the dermis into the epidermis thus hydrating it.

It is worth noting that some products have emollient properties only and some have both emollient and moisturising properties. In this content, the word emollient will be used to refer to products that soften the skin by increasing the level of moisture in the stratum corneum, i.e. an emollient moisturises the skin. The mechanisms for this are discussed later in this section.