Improving Sensitive Skin Diagnosis by Integrating Diagnostic Questionnaires, Lactic Acid Sting Test, and Lipid Profiling

Background: Sensitive skin (SS) is characterized by subjective symptoms, including burning, stinging, and itching, which occur with the use of cosmetics. Over 40% of the population experiences skin sensitivity, yet no clear standards for evaluating SS have been established. Aim: To diagnose SS by combining lactic acid sting test (LAST), skin irritation tests, and biophysical measurements with a developed questionnaire, validating the characteristics through quantitative analysis of natural moisturizing factors (NMF) and lipid profiles. Methods: The diagnostic questionnaires were administered to 975 healthy women from Beijing and Shanghai to evaluate their skin sensitivity. Among these, 154 participants from Beijing and 153 from Shanghai underwent physiological testing, which included a patch test, LAST, and biophysical assessments. For stratum corneum (SC) sampling, D-squame tape was used, and the levels of NMFs and lipids were quantitatively analyzed using UPLC-MS/MS. Results: The diagnostic questionnaires, especially when combined with LAST, improved sensitivity and reduced false negatives for identifying SS. The SS group exhibited notable differences compared to the NS group, including higher hydration and lower pH on the forehead, reduced ceramide and fatty acid levels, and fewer amino acids in the stratum corneum, although skin irritation scores were not significantly different. Conclusions: The combination of our diagnostic questionnaire with LAST was found to effectively distinguish key characteristics of SS. This methodology offers a valuable approach for enhancing the diagnosis and assessment of SS, which could, in turn, aid in the development of more targeted products for SS.