Impact of N,N-Diethyl-meta-toluamide (DEET) and Citronella on Skin Barrier Function

Background: Skin barrier function is crucial for maintaining homeostasis by protecting the body against external aggressors. Despite the widespread use of insect repellents, their effects on skin homeostasis remain insufficiently studied. This study aimed to evaluate the impact of insect repellents on skin barrier function. Methods: A cross-sectional study was conducted to measure skin parameters on the volar forearm after the application of water as a control, a plant-based repellent containing citronella, and a synthetic repellent containing DEET. Results: A total of 52 individuals participated; 46% were female, and the mean age was 23.78 ± 2.77 years. Both repellents induced changes in skin barrier function. Citronella increased temperature (31.24 vs 30.86 °C; P < .0001) and erythema (201.98 vs 191.61 AU; P = .0282), and decreased transepidermal water loss (TEWL) (6.35 vs 8 g/m²/h; P = .0023) and R0 elasticity (0.33 vs 0.37 µm; P < .0001), among other effects. DEET increased temperature (31.56 vs 30.86 °C; P < .0001) and stratum corneum hydration (SCH) (62.81 vs 55.39 AU; P = .0008), and decreased TEWL (5.69 vs 8 g/m²/h; P = .0005) and R0 elasticity (0.39 vs 0.37 µm; P = .0281). Comparisons between repellents showed that DEET produced significantly greater changes than citronella in skin barrier variables such as temperature, SCH, sebum, R0 elasticity, and TEWL. Conclusions: Both repellents altered skin barrier function, with DEET having a greater impact than citronella.