Benzalkonium Chloride is an organic compound that is used as an antiseptic and spermicide.

It is used in eyewashes , hand and face washes, mouthwashes, spermicidal creams, and in various other cleaners, sanitizers, and disinfectants. It is inactivated by organic material so is only applied to disinfect once the area is clean.

Benzalkonium chloride is a mixture of alkylbenzyl dimethylammonium chlorides. This product is a cationic quaternary ammonium surface-acting agent. It is very soluble in water, alcohol, and acetone. Aqueous solutions of benzalkonium chloride are neutral to slightly alkaline, generally colorless, and nonstaining. They have a bitter taste, aromatic odor, and foam when shaken.

Benzalkonium chloride solutions are rapidly acting anti-infective agents with a moderately long duration of action. They are active against bacteria and some viruses, fungi, and protozoa. Bacterial spores are considered to be resistant. Solutions are bacteriostatic or bactericidal according to their concentration. The exact mechanism of bactericidal action is unknown but is thought to be due to enzyme inactivation. Activity generally increases with increasing temperature and pH. Gram-positive bacteria are more susceptible than gram-negative.

Benzalkonium chloride is used as a surface disinfectant and detergent - primarily as hand scrub or face wash. It may also find application is a disinfecting agent for instruments, and in low concentration as a preservative for drugs including ophthalmic solutions. It is inactivated by organic compounds, including soap, and must not be applied to areas which have not been fully rinsed. This chemical lowers surface tension permitting better penetration in skin. It also is a cationic germicide.