Author: Isabelle Boileau, Medical Student, Faculty of Medicine, University of Ottawa, Ottawa, Canada; Justin Mori, Medical Student, Faculty of Medicine, University of Ottawa, Ottawa, Canada. DermNet NZ Editor in Chief: Adjunct A/Prof Amanda Oakley, Dermatologist, Hamilton, New Zealand. Copy edited by Gus Mitchell. June 2019.
Emollients are topical moisturising agents used to alleviate itchiness and other discomforts associated with eczema. Dry skin (xerosis), a common feature of eczema, is highly responsive to treatment with emollients .
Emollients work by filling the cracks in dry skin and forming an occlusive barrier, promoting moisture retention and maintenance of normal skin integrity and appearance to keep skin hydrated, flexible, and protected from irritants . Their use has been associated with reduced frequencies of flares and the use of topical corticosteroids .
Emollients vary in their water and oil contents. High oil/low water mixtures are generally recommended for skin hydration and barrier repair .
Emollients can be classified into two categories based on their ingredients; hydrophilic or hydrophobic [1,5]. Water-based, hydrophilic emollients exert a hydration effect by attracting water to the skin’s outer layer . Hydrophobic emollients reduce the loss of water through the skin by forming a protective barrier which prevents evaporation of moisture .
Although the term emollient is often considered synonymous to a moisturiser, the former can also be described as a specific ingredient of the latter. Moisturisers can be categorised into groups based on their mechanism of skin hydration.
Selection of an emollient is based on eczema severity and the patient’s preference. The ideal emollient should be pleasant to use, optimise skin appearance, and restore the skin barrier. In addition, it should contain only a few ingredients and ideally avoid irritants/allergens such as fragrances .
Emollients come in a variety of formulations, such as lotions, creams, gels, and ointments. Furthermore, emollients can be categorised according to their application, such as leave-on, soap substitutes, and bath additives. All three application approaches are often used together . However, the exclusive use of bath emollients has been shown to provide a substandard therapeutic effect compared to leave-on emollients .
Leave-on emollients are applied directly to the skin. They vary in consistency from light to heavy. Light preparations, such as creams and lotions, are quickly absorbed owing to their high-water content but require more frequent application than thicker ointments. Light preparations are suitable for a broad area of application. Heavy preparations (ointments) have an occlusive, protective, longer lasting effect due to their higher oil content, but are usually less cosmetically acceptable due to their oily appearance . Typically, chronic eczema patients will prefer to use a heavy preparation, especially when applied to a small area.
Soap can be used on body folds but should be completely rinsed off. Soap should seldom be used for the rest of the body as it irritates the skin. Emollient soap substitutes are preferred when washing the rest of the body .
Bath emollients are oils or emulsifiers designed to disperse in the bath .
Emollient therapy may be sufficient to control mild eczema and to eliminate symptoms .
Regular, liberal use of emollients can significantly reduce the severity of established eczema. Multiple studies have demonstrated that emollient therapy has a role in reducing the frequency and rate of flare-ups and the need for topical steroids while at the same time improving disease control by ameliorating skin barrier defects [1,11].
For optimal results, it is best to apply emollients to damp skin after bathing but they can also be applied to dry skin at any time . Regular application two to three times per day is recommended . The amount applied averages from 150–200 g per week in young children to 500 g in adults . The therapeutic effects of emollients are reduced 6 hours after application .
Emollient ingredients may irritate the skin or cause contact dermatitis in some people. Stinging or burning can result in poor compliance, which may decrease their therapeutic effect . The application of an emollient can also be time-consuming and leave residues on clothes and furniture . Clothing soaked with paraffin-containing emollients is flammable and a fire hazard.
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