The effectiveness of using a bath oil to reduce signs of dry skin: A randomized controlled pragmatic study

Abstract

Background

Dry skin (xerosis cutis) is increasingly recognized as a relevant health problem in daily life and in health and nursing care. The use of bath additives such as oils is common to reduce dry skin, but empirical evidence supporting this practice is limited.

Objectives

The aim of this study was to investigate the effectiveness of using a bath oil additive in improving skin barrier function and ameliorating dry skin in comparison to non-oil containing skin cleansers for bathing or showering.

Design

Single centre randomized observer blind pragmatic parallel group trial.

Settings

Outpatient/community care.

Participants

Volunteers showing clinically mild to moderate dry skin recruited from the city of Berlin.

Methods

Healthy children and adults were randomly assigned to use either a commercially available bath oil or to continue using their regular non-oil containing skin cleansers every other day over a study period of 28 days. Skin barrier parameters and the severity of dry skin were assessed at baseline and at two follow-up visits at the study centre. Transepidermal water loss was the primary outcome.

Results

All sixty participants randomized completed the trial. Median age was 32.5 (IQR 8.3 to 69) years. At the end of study the mean transepidermal water loss in the intervention group was statistically significant lower compared to the control group (mean difference −1.9 (95% CI −3.1 to −0.8) g/m²/h). Stratum corneum hydration was statistically significantly higher in the intervention group at the end of the study. Skin surface pH and roughness were comparable in both groups and remained unchanged, while both groups showed a trend to improvement in dry skin symptoms

Conclusions

This pragmatic trial provides empirical evidence that the regular use of the investigated bath oil is effective in improving the skin barrier function in children and adults with mild dry skin when used in routine skin care and supports its use as a basic element for the management of a broad spectrum of dry skin conditions.

Trial registration

ClinicalTrials.gov Identifier NCT02557698.

Introduction

Dry skin (xerosis cutis) is increasingly recognized as a relevant health problem in daily life and in health and nursing care settings (Hardy, 1990, Kottner et al., 2015). Due to inflammatory skin diseases (e.g. atopic dermatitis), unfavourable environmental conditions (e.g. low humidity during winter, frequent use of harsh soaps), or due to ageing-related skin changes the stratum corneum, the uppermost layer of the epidermis, is unable to maintain a sufficient water concentration gradient between the living epidermal cells and the skin surface (Rawlings and Harding, 2004, White-Chu and Reddy, 2011). This results in a stratum corneum that is too dry, especially in the uppermost cell layers. Dry skin is usually associated with an impaired skin barrier function manifesting as increased transepidermal water loss (Kottner et al., 2013a, Rogiers, 2001). Symptoms of dry skin range from unpleasant feelings of itch and ‘tightness’ and a scaly and flaky appearance, to severe inflammation and cracks with high risk of secondary infection (White-Chu and Reddy, 2011). Severe itch with scratching is one of the most burdensome and distressing symptoms in dry skin (Berger et al., 2013).

Epidemiological studies suggest that dry skin is frequent across the life course. It is a key symptom of atopic dermatitis (Simpson et al., 2012) which starts early in life and is increasing worldwide. Depending on the diagnostic criteria applied and country reported prevalence figures range from 4% to 28% in early childhood (e.g. Draaisma et al., 2015, Doğruel et al., 2016, Guo et al., 2016) decreasing to 2 to 7% in adults (e.g. Saeki et al., 2009, Hwang et al., 2010). A recent population-based survey in the United States reported a one year prevalence of 10% in adults (Silverberg and Hanifin, 2013). Skin dryness is also associated with a number of internal diseases, for instance with diabetes mellitus (Demirseren et al., 2014) which is also increasing. Irrespectively from disease related symptoms, dry skin is especially prevalent in the elderly. Dry skin and itch were reported to be the most common skin concerns of senior community citizens in the USA (Caretti et al., 2015). In elderly populations prevalence estimates range from 48 to 85% in community and outpatient care settings and from 20 to 77% in institutional care (Smith and Leggat, 2005, Lichterfeld et al., 2016).

Common interventions for the management of dry skin are use of mild skin cleansers, reducing the frequency and the duration of exposure to water, and topical application of lipophilic and humectant containing skin care products (Guenther et al., 2012, Lichterfeld et al., 2015). The use of bath additives such as oils is also common. Scientific reports of using bath oils to ameliorate dry skin date back to the 1950s (Franks, 1958). The assumed mechanism of action of bath oils is by depositing a lipid film which remains on the skin surface after the bath. Consequently bath oils are sometimes regarded as moisturizing leave-on products applied to a large skin surface area (Hill and Edwards, 2002). Although bath oils are widely used at home and in care settings published scientific evidence supporting this practice is limited. Studies investigating effects of baths oils were either conducted on small selected investigational skin areas (Gloor et al., 1975, Stender et al., 1990) or by using artificial skin irritation models (Hill and Edwards, 2002, Puschmann, 1991). Thus in recent systematic reviews addressing evidence based skin care, studies investigating the effects of bath oils are lacking (Cowdell and Steventon, 2015, Kottner et al., 2013b, Lichterfeld et al., 2015). As skin cleansing and caring are fundamental activities in nursing practice, there is an urgent need to underpin skin care interventions by empirical evidence, especially regarding emollient and moisturizing practice (Penzer, 2010). Because bath oil additives are widely applied in various populations and settings, the aim of this clinical trial was to investigate the effectiveness of using a bath oil additive in comparison to non-oil containing skin cleansers for bathing or showering in the treatment of dry skin.