Benzalkonium chloride is a quaternary ammonium antiseptic and disinfectant. It is also used as an antimicrobial preservative for pharmaceutical products. It is also used for the disinfection of rigid contact lenses.

Higher concentrations of Benzalkonium chloride is used as an antiseptic and disinfectant. This is also widely used as a preservative in eye-drops.

• Tincture of benzalkonium chloride 1:750 is used for the preoperative disinfection of unbroken skin or treatment of superficial injuries.
• For preoperative disinfection of mucous membranes and denuded skin, benzalkonium chloride solution in concentrations of 1:10000 to 1:2000 is used.
• For irrigation of the eye, a solution of 1:10000 to 1:5000 is used.
• For urinary bladder and urethral irrigation, a solution 1:5000 to 1:20000 is used.
• For vaginal douche and irrigation, benzalkonium chloride solution 1:5000 to 1:20000.

Incompatible with soaps and other anionic surfactants, citrates, iodides, nitrates, permanganates, salicylates, silver salts, tartrates, and zinc oxide and sulfate.

Repeated application may cause hypersensitivity reactions. May cause nausea and vomiting if ingested.