In a 72-day randomized trial involving 568 participants in Japan, an experimental hand sanitizer containing ethanol, benzalkonium chloride, and lactic acid was associated with a 40% lower cumulative incidence of upper respiratory symptoms than a commercial ethanol-based sanitizer. Participants using the experimental formulation also experienced fewer illness-related work restrictions, although infections were not laboratory-confirmed and the proposed residual antimicrobial mechanism was not directly tested.