J. Soc. Cosmetic Chemists, 16, 317-340 (1965) Use of Anti-Irritants Formulating in Cosmetic ROBERT L. GOLDEMBERG, B.S.* Presented before the Third Congress of the I.F.S.C.C., .rune 21-26, 196•, New York City Synopsis--An anti-irritant is defined as an agent which, when used in conjunction with skin or eye irritants, reduces their irritation potential sufficiently to be tolerated when applied to the body. Three different mechanisms are postulated for the activity shown by various anti-irritants: Some operate by "complexing" the irritant itself. Others react with the skin, blocking reactive sites so that the irritant cannot react with it. A final group seems nonreactive and apparently protects by merely preventing complete physical contact between irritant and skin. Examples of each mode of action are given. The major portion of the report presents irritation test data showing specific anti-irritant activity, or lack thereof, for a number of agents which were added to various types of cosmetic formulas. In particular, an antiperspirant formula is developed step-by-step, with the ir- ritant effect of each component determined. An appendix lists several dozen agents for which anti-irritant properties have been claimed, together with a summary of the evidence backing such claims. INTRODUCTION It has been known since pre-history that certain natural materials have a soothing effect when applied to irritated skin. Primitive witch doctors often included such ingredients in magic potions which thereby developed mysterious curative powers, especially when applied to the accompaniment of suitable incantations and dances. Many of these same ingredients, plus a number of newer synthetic agents, are used today in cosmetic and dermatologic preparations for their actual or supposed curative powers. It is assumed that they promote the healing of various types of skin irritation. Many formu- * Charles of the Ritz, South Norwalk, Conn. 06854. 317

318 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS lators feel it "self-evident" that such soothing ingredients must also act as anti-irritants if applied to the skin in conjunction with known irritants. Unfortunately, this self-evident assumption is not always justified. In recent years it has been learned that safety is a relative matter. No material is absolutely safe to use on the skin unrestrictedly, nor does anything exist which is always unsafe. Materials which are known to be soothing to irritated skin will not always act as anti-irritants when mixed with inflammatory or otherwise irritating agents. The purpose of this paper therefore is not to establish absolutes nor to provide lists of ingredients guaranteed to make products safe. Instead, the purpose is to show that the skin and eye irritation potential of various cosmetic ingredients can vary greatly, dependira', on •heir "en- vironment" (i.e., other components of the formulation), and on the mzthod of use and bodily area to which thefinished formulation is applied. A corollary of this argument is the inescapable conclusion that "positive" (safe) and "negative" (unsafe) lists of cosmetic ingredients, such as have been suggested in several European countries as "guides" or as devices for regulating the activities of cosmetic manufacturers, have no sound scientific basis. There is no question that the irritative properties of many ingredients can be altered drastically by suitable compounding techniques. Therefore, it must also be evident that the irritation potential of a cosmetic cannot be determined solely on the basis of the known irritative properties of each of its individual com- ponents. The irritation characteristics of components are no additive. They often exhibit a synergism, either positive or negative, which appears at random and is unpredictable. These synergistic effects are the basis of several recent patents (1-3) concerned with anti-irritant combinations. It would not be wise, therefore, to draw generalizations from the anti-irritant effects noted in this paper. Some agents may be useful only in the specific formulations which were tested. It will also be shown later that some materials can act as anti-irritants in one type of formula and then reverse their roles and increase the irritation potential of a different type of product. GENERAL BACKGROUND Cosmetic chemists must beware the temptations of two sirens, medicine and cosmetology, who stand on opposite shores of the nar- rows through which they sail, waiting to seduce and destroy those who