Benzalkonium chloride (BAC) is a quaternary ammonium compound with broad-spectrum antimicrobial activity, widely used as a disinfectant, antiseptic, and preservative in medical, industrial, and household products. As a cationic surfactant, it disrupts microbial cell membranes, causing leakage of cellular contents and microbial death, which makes it effective against bacteria, fungi, and some viruses. BAC was first synthesized in the 1930s during research into cationic surfactants for disinfectant purposes, and by the 1940s, it became recognized for its utility in hospitals and industrial sanitation. Over time, its applications expanded to include ophthalmic solutions, nasal sprays, and personal care products, valued for its stability and low toxicity at appropriate concentrations. Despite occasional concerns about skin irritation or potential microbial resistance with prolonged use, BAC remains one of the most commonly employed antiseptics worldwide due to its effectiveness, versatility, and ease of formulation, reflecting nearly a century of continued research and practical application
