Skin Cleansers Aid Sensitive Skin

Skin cleansers may be an important adjunct to the regimen of those who use cosmetics, have sensitive or compromised skin, or utilize topical therapies. Cleansers emulsify dirt, oil and microorganisms on the skin surface so that they can be easily removed. During cleansing, there is a complex interaction between the cleanser, the moisture skin barrier, and skin pH. Cleansing, with water, soap or a liquid cleanser, will affect the moisture skin barrier. Soap will bring about the greatest changes to the barrier and increase skin pH. Liquid facial cleansers are gentler, effecting less disruption of the barrier, with minimal change to skin pH, and can provide people with a cleanser that is a combination of surfactant classes, moisturizers and acidic pH in order to minimize disruption to the skin barrier.

Skin cleansers are surface-active substances (i.e., emulsifiers/detergents/surfactants/soaps) that lower the surface tension on the skin and remove dirt, sebum, microorganisms and exfoliated corneum cells in an emulsified form. The ideal cleanser should do this without irritating, damaging or disrupting the skin and the moisture skin barrier. Water alone removes approximately 65% of oil and dirt from the skin, but is less effective at removing oils of cosmetic import and some environmental insults. Soaps are the oldest surfactants, and are chemically defined as the alkali salt of fatty acids with a pH of 9.5-10. Synthetic detergents vary in composition and surfactant types (i.e., anionic, amphoteric, cationic, non-ionic, and silicone) and pH. In modern usage, the term “soap” generally refers to any cleansing agent regardless of chemistry.1

Skin cleansers consist of the following:
• Water
• Surfactants (to emulsify the debris)
• Moisturizers (to hydrate the skin and maintain the skin barrier)
• Binders (to stabilize the formulation)
• Lather enhancers (found in some products)
• Fillers (generally used to harden bar soaps and cleansers)
• Preservatives (to prevent the growth of microorganisms)
• Fragrance (generally used to mask the odour of surfactants)
• Dyes or pigments (found in some products)

Skin cleansing may disrupt or disturb the moisture skin barrier, affect the skin surface pH, and irritate the skin. The moisture skin barrier protects against transepidermal water loss, chemical insult and xenobiotic penetration while preserving water to moisturize and maintain the smoothness and flexibility of the skin. A compromised barrier has been correlated with psoriasis, ichthyoses, and atopic dermatitis.2 Moisturizers, both emollients and humectants, within cleansers can maintain skin hydration as well as maintaining and restoring barrier function.3 Emollients impair evaporation of skin moisture by forming a film on the skin surface to impede water loss. Humectants attract and bind water, drawing it up from the dermis into the epidermis. The acid mantle of the skin plays an integral role in skin barrier function as well as regulating bacterial flora.4 Studies have shown that skin barrier regeneration/repair proceeds more slowly at neutral pH (7.2) than at physiological pH 5.5.5 Cleansers may also cause irritant or allergic contact dermatitis and this effect is enhanced if the skin barrier is compromised.

Conclusion

The choice of facial cleanser is important for people with normal skin, as well as for those people with sensitive skin and skin diseases such as atopic dermatitis, acne vulgaris. Liquid facial cleansers are the best choice for facial cleansing as they have an acidic pH, moisturizers and high rinsibility. Within the liquid cleanser category, the least irritating cleanser will contain non-ionic/silicone-based surfactants combined with moisturizers, as they will cause the least disruption to the moisture skin barrier and the normal skin flora.

B. L. Kuehl, PhD1 , K. S. Fyfe, H BBA2, N. H. Shear, MD, FRCPC3

1Scientific Insights Consulting Group, Mississauga, Ontario Canada
2GlaxoSmithKline, Consumer Healthcare, Oakville, Ontario Canada
3Departments of Medicine (Divisions of Dermatology and Clinical Pharmacology), and Pharmacology, University of Toronto Medical School; and Division of Dermatology, Sunnybrook & Women’s College Health Sciences Centre, Toronto, Ontario, Canada