Evolving Surfactant Trends in the Thai Personal Care Market Over 15 Years and Their Association with Clinical Patch Test Reactivity

Background: Surfactants in personal care products are an established trigger of allergic contact dermatitis. However, regional data comparing market usage with sensitization rates remain limited. Objectives: To examine 15-year trends in Thai surfactant prevalence and correlate them with clinical patch test reactivity. Methods: Surfactant prevalence in 6864 personal care products was surveyed using the Thai Contact Allergen Avoidance Program database (2010–2024). Concurrently, patch test results from 6603 patients were analyzed across 3 5-year intervals. Results: Cocamidopropyl betaine (CAPB) was the most prevalent surfactant overall (20.3%) and in cleansers (43.2%), whereas polysorbates predominated in non-cleansing formulations (17.9%). In cleansers, use of CAPB ( P < 0.001), glucosides ( P = 0.009), and cetrimonium chloride ( P < 0.001) rose over time. Cetrimonium bromide, benzalkonium chloride, and CAPB showed the highest patch test positivity rates. Conversely, positivity declined for CAPB ( P < 0.001), benzalkonium chloride ( P = 0.007), lauryl glucoside ( P = 0.019), and cocamide diethanolamine ( P < 0.001). Conclusions: The Thai market is shifting toward milder surfactants. A paradoxical decline in CAPB and lauryl glucoside sensitization occurred despite their rising prevalence. Continuous market monitoring is essential to keep patch test series and patient counseling relevant.