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Background: Cosmetic products are widely used in daily life and can cause skin reactions. However, to date, few studies have investigated the prevalence and associated factors of skin reactions to different types of cosmetic products using patch test results., Objectives: To investigate the frequency and associated factors of skin reactions to sunscreens, skin whitening products, and deodorants using patch test results in China., Methods: This cross-sectional analysis used data collected during 2004-2017 at the Shanghai Skin Disease Hospital, China. Skin reactions were measured using patch tests following internationally standardized protocols., Results: In total, 151 280 patch tests comprising 16 477 cosmetic products conducted in 4029 healthy volunteers were analyzed. The frequencies of skin reactions to different cosmetic products were 1.07%, 1.28%, and 4.41% for sunscreens, skin whitening products, and deodorants, respectively. With increasing age, a higher frequency of reactions to sunscreens in women (p < 0.001) and a lower frequency of reactions to skin whitening products in men (p < 0.05) were observed. In addition, men were more likely to develop skin reactions to deodorants compared to women (p < 0.05). Skin reactions were more frequent in winter (p < 0.05), which was true for different types of cosmetic products., Conclusions: The frequency of patch testing for different cosmetic products was 1.07-4.41%. The effects of age, sex, and season vary among the different types of cosmetic products. We hope that these findings can offer guidance for a healthy skincare concept., (© 2021 Wiley Periodicals LLC.)

Background: Patch test, as a helpful tool in clinic diagnosis and safety assessment of cosmetics, is affected by many factors., Objectives: To investigate the influencing factors of patch test reactions in a highly standardized large-scale dataset of Chinese., Methods: Patch test data (n = 151,280) from safety assessments of cosmetic products were obtained following internationally standardized patch testing protocols during 2004-2017 in China., Results: The frequency of patch test reactions was 1.45% (2,191/151,280), with majority of the reactions being "score 1" reactions (also known as doubtful reactions, n = 2,075) and a small number being "score 2" reactions (weak reactions, n = 116). Patch test reactions were 67% more frequent in winter (p < 0.001), associated with temperatures (p < 0.001), rather than relative humidity (P:0.29). The frequency of reactions was higher in men than in women (p:0.001), especially in winter. The risk to develop reactions clearly increased with age in women (p < 0.001), but not in men (p:0.14). In women, the frequency of reactions in the old group (≥50 years old) was 30% more than the young group (<30 years old)., Conclusions: The frequency of patch test reactions to cosmetic products was 1.45% in our large-scale study. The influencing factors of patch test include season, sex, and age, which should be considered when conducting and interpreting patch testing., (© 2021 Wiley Periodicals LLC.)

Background: There are increasing cosmetic adverse reactions in China, mostly cosmetic contact dermatitis, with the development of its cosmetics industry., Aims: To identify the allergens and cosmetics products responsible for cosmetic allergic contact dermatitis (CACD) in Shanghai., Methods: Five hundred and sixty patients, including 342 suspected CACD patients from dermatological clinic and 218 cosmetics consumers with an allergic history, were patch tested with a cosmetic series (C-1000 series). And 154 patients patched with possible culprit cosmetics., Results: Two hundred and forty-six subjects showed positive reaction to C-1000 series. Clinic patients had much higher positive rate than that of cosmetics consumers. Leading allergens were methylisothiazolinone (MI), methylisothiazolinone + methylchloro-isothiazolinone (MCI/MI), thimerosal, and the positive rates were significantly higher in patients than in cosmetic consumers (P < .001 for all). MCI/MI elicited positive patch test reactions in 73.5% of MI-positive patients. Of those patched with cosmetic products, 19 patients had 31 positive reactions, including 22 skin care products and 5 color decorating., Conclusions: Preservatives, especially MI, MCI/MI, and thimerosal, were the most common cosmetic allergens, and skin care products occupied the most allergic reaction of CACD. Patch testing is highly recommended for suspected CACD patients. Future comparative investigation with large sample size should benefit cosmetovigilance surveillance., (© 2019 Wiley Periodicals, Inc.)