GD — Society for Dermopharmacy

Issue March 2001

The cleansing of dry skin (2) involves the following risks:

Degreasing of the skin by washing off the sebum as well as partially also the horny layer lipids

Dehydration of the skin by reducing of the water binding capacity of the skin as consequence of the washig out of the natural humectant agents

Disturbance of the barrier function of the horny layer, already impaired with this skin condition, by changing of the lipid structures, swelling or raising the pH-value above the physiological weakly acidic sector

Skin irritations, to a minor degree also triggering of allergic contact eczema and triggering of the atopical eczema (neurodermitis) at the appropriate predisposition.

Each cleansing process of the skin leads to an impairment of the barrier function. By selecting of a suitable skin cleansing agent, this influence can be controlled and minimized (3-6). Furthermore, the risk is reduced by choosing the qualified skin cleansing measures: washing stresses the skin less than having showers or baths and comes up to the hygienical demands provided that the washing process is performed thoroughly. For dry skin maximally one shower a day respectively three full baths per week are recommended. The water temperature should not exceed 35 ° (7). The duration of the shower should be limited to 10 minutes, of the bath to 20 minutes maximum. Skin cleansing agents should be spread sparingly on the wet skin and after briefly taking effect they are to be completely rinsed off.

Cleansing products for the dry skin should at the same time have a satisfactory cleansing effect and the least possible risks regarding desiccation, degreasing, barrier disturbance and skin irritation. Mainly offered are preparations which develop the cleansing effect strived for by surfactant-active substances (surfactants) also in case of heavy soiling. Different types of surfactants are distinguished, e.g. anionic and non-ionic. Soaps, i.e. anionic surfactants which are produced by "saponification" of vegetable or animal fats with caustic soda solution are in general less suitable for the cleansing of dry skin because of their alkaline reaction which attacks the natural acid protective barrier of the skin more than the so-called syndets (8). Syndets are adjusted to the physiological pH-value of the skin (9) and can thus be conceived in a more skin protective way (10-12). Determinative for the benefit-risk relationship of a cleansing product is besides the type of surfactants - degreasing and irritative substances as sodium lauryl sulphate should be avoided (4) - also the quantity employed. By using of care additives in the formulation it can be tried to counteract the loss of fat and humidity (5). Surfactant-free skin cleansing agents only have a weak cleansing effect in the most favourable case (2) and can therefore at the time being not be considered as alternative in general. However, there is no reason for an extension to the so-called soap-prohibition of the thirties in favour of the modern syndets.

The extent of risks for the application of all types of cleansing products is determinable for both the surfactant and the surfactant-free products by appropriate dermatologic examinations. These tests should be performed at test subjects with dry skin by inclusion of objective assessment criteria as measurements of the fat- and humidity content as well as its barrier function. In the guidelines "Dermocosmetics for the Cleansing of Dry Skin" of the Gesellschaft für Dermopharmazie (Society for Dermopharmacy) (published in the GD-Homepage at www.gd-online.de), the results of such tolerance and care effect studies are called for as proof for the suitability of cleansing products. Consumers, sellers of cosmetics as well as physicians and pharmacists should orient their purchasing decision according to the fact whether or not the producers of the products for the cleansing of dry skin are able to prove their suitability on the basis of such examination results. Simplifying assessments, e.g. by means of the presence or absence of surfactants in the cleansing product are not sufficient as a decision basis.

References

(1) Gloor M.: Nutzen und Risiko von Kosmetika und Dermatika: Bewertung aus der Sicht des Dermatologen. In: Braun-Falco O., Gloor M., Korting H.C.: Nutzen und Risiko von Kosmetika. Springer Verlag Heidelberg 2000, S. 198-205
(2) Schürer N., Kresken J.: Trockene Haut. Wiss. Verlagsges.mbH, Stuttgart 2000, S. 82-86
(3) Gottfreund J., Meyer T.: Hautverträgliche Rezepturen für die medizinische Körperreinigung. Seifen Öle Fette Wachse-Journal 8, 494-498, 1998
(4) Gehring W., Gloor M., Kleesz P.: Predictive washing test for evaluation of individual eczema risk. Contact Dermatitis, 39, 8-13, 1998
(5) Welzel J., Wolff H.H., Arens-Corell M.: Zur Verträglichkeit neuentwickelter Hautreinigungsprodukte. T&E Dermatologie, 28, 63-66, 1998
(6) Schrader K.H., Rohr M.: Tenside - ihre Beurteilung hinsichtlich Wirkung und Nebenwirkungen. Euro Cosmetics, 1-2, 18-22, 1994
(7) Berardesca E., Vignoli G.P., Distante E., Brizzi P., Rabbiosi G.: Effects of water temperature on surfactant-induced skin irritation. Contact Dermatitis, 32, 83-87, 1995
(8) Stauffer H.: Die Ekzemproben (Methodik und Ergebnisse). Arch. Dermatol. Syph., 162, 562-576, 1930
(9) Korting H.C., Braun-Falco O.: The effect of detergents on the skin and its consequences. Clinics in Dermatology, 14, 23-27, 1996
(10) Gehring W., Kemter K., Nissen H.-P., Gottfreund J., Gloor M.: Vergleichende Untersuchungen zum entfettenden Einfluss einer Waschlösung. Z.Hautkr., 70, 643-648, 1995 (11) Gfatter R., Hackl P., Braun F.: Effects of soap and detergents on skin surface pH, Stratum corneum hydration and fat content in infants. Dermatology 195, 258-262, 1997
(12) Gehring W., Gehse M., Zimmermann V., Gloor M.: Effects of pH changes in a specific detergent multicomponent emulsion on the water content of stratum corneum. J. Soc. Cosm. Chem., 42, 327-333, 1991

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