Protective Effects of Moisturizers on Skin Barrier during Regular Hand Washing with Soap Bars

Sir,

Repetitive use of soaps damages the epidermal barrier, and high risk groups are advised to use moisturizers after hand washing; however, there is no enough evidence to clarify whether normal people with healthy skin will benefit from using moisturizers during daily handwashing. The aim of the present study was to assess the protective effect of moisturizers after regular hand washing on skin barrier function using skin biophysical parameters as the signs of irritation and barrier damage.

It was a randomized controlled clinical study. Sixty participants with dry skin aged 30.6 + 10.21 washed both forearms four times a day for 7 days using soap bar. In each subject, right or left forearm was randomly allocated as the test side for applying a moisturizer after washing with soap and the other side as only soap wash control site. Test moisturizer contained aqua, paraffinum liquidum, glycerin, cyclomethicone, stearic acid, cetyl alcohol, triglyceride, peg-8 beeswax, cholesterol/lanostrol, and tromethamine.

Biophysical properties of the skin including trans epidermal water loss (TEWL), erythema, friction, and skin pH were measured on both sites according to time schedule showed in Figure 1. The differences between each parameter change were analyzed for significance using the paired sample t-test.

Figure 1.

Schedule of measurements of skin biophysical parameters before and after hand washing

The increase in TEWL and skin pH immediately after washing with a soap was considerably reduced with the application of moisturizer [Figure 2a and 2b]. Reduction in TEWL is because of occlusive agents presented in the moisturizer (paraffinum liquidum, cyclomethicone, and beeswax), which form an inactive layer on the skin surface, and physically block water evaporation from the skin.[1]

Figure 2.

Comparing the change in skin biophysical parameters between two sides with only soap wash and soap with moisturizer application in T1 to T5 assessment times; (a): TEWL; (b): skin pH; (c): skin Friction; and (d): skin erythema index (* P ≤ 0.05)

Significant improvement occurred in skin friction and erythema index in side with moisturizer application compared to control (P-value = 0.01) [Figure 2c and 2d]. Skin friction as the resistance against the movement of objects positively correlates with stratum corneum hydration.[2] Hydration solubilizes proteins and their adhesive properties increase skin friction. Hydration also softens the stratum corneum and increases the contact area between probe and skin, resulting in a higher skin friction coefficient.[3]

Moreover, the test moisturizer contains emollient substances (fatty acids and fatty alcohols) and humectant agent (glycerin), which reduce the skin pH and recover the skin buffering capacity. Lower skin pH improves barrier function via increasing lipid production and reduced the damage to exogenous stress.[4]

The most serious barrier damage showed to occur right after hand washing with soap, when the skin erythema, pH, and TEWL reach the maximum level of increase. This immediate damage could also be due to additional effect of water evaporation during washing.[5] In the following hours, skin regenerative mechanisms started to compensate the external damage and repaired the barrier. Moreover the best protective effects of the moisturizer in current study was right after hand washing in period of acute barrier damage, before the skin gets enough time for self-healing.

Consequently, application of a moisturizer immediately after regular hand washing is capable of maintaining the skin barrier function in the skin, mainly during the acute barrier damage phase.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.