Effectiveness of emulsion bathing in adult patients with atopic dermatitis

Emulsion bathing has been commonly advised in the management of atopic dermatitis (AD) to maintain skin hydration and reduce the negative effects of soaps on the skin barrier. However, there is limited scientific evidence from randomized controlled trials to support their effectiveness.

We aimed to compare the moisturizing effectiveness of 2 regimens: emulsion bathing combined with moisturization and moisturization after bathing with tap water only, in adults with AD.

Thirty-nine adult patients with AD (aged 20-63 years) were recruited. The right and left forearms of each subject were randomly assigned to be immersed and washed for 3 minutes with either moisturizing bath oil (dual-therapy group) or tap water alone (monotherapy group), followed by air drying for 30 minutes. Subsequently, a moisturizer was applied to the tested skin areas. Stratum corneum hydration (SCH) and transepidermal water loss (TEWL) were measured using a GP Skin Pro device (Gpower, South Korea) at five time points: before washing (baseline), after washing and air drying for 30 min (postwash), and after moisturization at 0, 30 and 60 minutes.

At the postwash time point, mean SCH levels in both groups decreased significantly; however, the mean SCH level of the dual-therapy group was significantly higher than that of the monotherapy group (20.9 ± 8.4 a.u. vs 14.4 ± 9.96 a.u., P = 0.006). Additionally, the mean TEWL level of the dual-therapy group was significantly lower than that of the monotherapy group (6.73 ± 2.7 g/m²/h vs 8.53 ± 3.1 g/m²/h, P = 0.009). After moisturizer application, both study groups demonstrated significant increases in SCH and decreases in TEWL levels. However, no significant differences in SCH and TEWL levels were observed between the 2 groups after moisturization at 0, 30, and 60 minutes.

Emulsion bathing helped prevent epidermal damage induced by bathing. However, the combination of emulsion bathing and moisturization did not show superiority over moisturization alone in improving skin hydration after bathing.