J. Soc. Cosmet. Chem., 43, 195-206 (July/August 1992) Absence of effects of dimethicone- and non-dimethicone-containing shampoos on daily hair loss rates PREYA KULLAVANIJAYA, PIMONPUN GRITIYARANGSAN, PRAVIT BISALBUTRA, RANOKVALAI KULTHANAN, and CAROLINE W. CARDIN The Institute of Dermatology, 420/7 Rajvithi Road, Bangkok 10400, Thailand (P.K., P.G., P.B., R oK. ), and The Procter & Gamble Company, Sharon Woods Technical Center, Cincinnati, OH 45241 (C. W. C. ). Received June 15, I991. Synopsis Shampoos are designed for cleansing and conditioning hair. During normal use, these products come in contact with hair and skin in very diluted concentrations for very short periods of time and are generally recognized as safe by dermatologists (1). Despite the above, when consumers change hair care products, they have a tendency to be more attentive to the conditions of their hair and scalp and to attribute any perceived change, especially any seen as negative, to the new product. One issue that is always of concern is hair loss or, in consumer terms, hair fall occurring shortly after switching to a new shampoo. To understand why consumers associate hair fall to the use of shampoo, a clinical study was conducted to examine daily hair loss rates in a large population of 404 healthy Thai females using either a dimethicone- or non-dimethicone-containing cosmetic shampoo for a period of six weeks. In addition, perceptual infor- mation was obtained on hair fall, hair health, and causes of hair shedding and hair loss. While published estimates of average daily hair loss rates range from 34.8 to 180 hairs (2-7), this study found mean hair loss rates ranging from 28 to 35 per day in a population of 404 healthy Thai females over a period of six weeks. These daily hair loss rates are consistent with reported findings in the normal population (2-3,8). There were no significant differences in the total, telogen, anagen, and broken hair loss rates between the three different shampoo groups. As expected, significantly higher hair loss rates were noted on shampoo versus non-shampoo days. No differences were noted in the perception of hair fall in subjects using the three different shampoos. In this study, we determined why consumers associate hair fall with the use of shampoo. While subjects perceived hair fall as a natural process in hair regrowth and therefore unrelated to hair thinning or balding, they attributed any increased hair fall from grooming to the use of unsuitable shampoos, more so than to the grooming processes of combing/brushing or to chemical modification. Other factors known to contrib- ute to abnormal hair loss were not perceived by the subjects as likely causes of hair fall. 195

196 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS INTRODUCTION It has long been recognized that cyclic hair growth activity occurs in a random mosaic pattern in which each hair enters anagen (active growing phase), catagen (involutional phase), and telogen (resting phase) independent of other hairs. This results in a daily shedding process in which telogen hairs are shedded and replaced by new anagen hairs (2-7,9-10). Since 85% to 90% of the hair is in the anagen phase and there are approximately 100,000 hairs on the head, the reported average daily telogen hair loss ranges anywhere from 34.8 hairs (2), 40-100 hairs (3), 100 hairs (4,7), 100-150 hairs (5), to 100-180 hairs (6). In general, the anagen phase is longer in women than in men (5). During pregnancy, the proportion of hairs in anagen phase may increase to greater than 95%, thereby decreasing the average shedding rate to 15-20 hairs per day (5). Many factors can lead to increased, abnormal hair loss (4,7,9-22). These include hor- monal changes (3,7,9-22), acute and chronic illness (4,7,9-14), scalp infections (3,7,9-14), trauma (3,7,9-15), medication (3,7,9-22), nutritional deficiency (9-22), endocrine disorders (3,7,9-14), and hereditary predilection (3,7,9-14). Although in- correctly used perms and hair colorants can lead to hair breakage as a result of overpro- cessing during chemical modification (1), shampoos have long been recognized as safe for use on hair (1). Most traditional shampoos contain anionic surfactants to cleanse the hair. Conditioners contain fatty alcohols and cationic surfactants to lubricate and neutralize the negative charges on the hair. Since anionic surfactants are negatively charged and cationic sur- factants are positively charged, the cleansing and conditioning functions from tradi- tional shampoos and conditioners have to be separated in a two-step process because they cannot exist together in one product. Dimethicone shampoos differ from traditional shampoos in that they clean and condition hair in a single step. This is achieved by the deposition of non-charged hydrophobic dimethicone droplets to condition hair without interfering with the cleaning ability of the anionic surfactants (23). MATERIALS AND METHODS GENERAL OUTLINE A total of 460 Thai females between the ages of 18 and 60 years were screened for eligibility to participate in the study. Prior to participation, they were questioned by dermatologists regarding their medical history and medication intake. The subjects then underwent scalp and hair examinations to assess the severity of scalp flaking and in- flammation, the presence or absence of scalp diseases, the degree of hair dryness and hair damage, and abnormal hair loss. The severity of scalp flaking was assessed on a 5-point scale ranging from no flaking (0) to severe flaking (5). Scalp erythema, if present, was assessed on a 4-point scale ranging from slight (1) to severe (4). Scalp disease was assessed on a 5-point scale where 1 represented non-diseased scalp, 2 represented dandruff, 3 represented seborrheic der- matitis, 4 represented psoriasis, and 5 represented eczema. Hair dryness was assessed on