Benzalkonium chloride also known as alkyldimethylbenzylammonium chloride (ADBAC) and by the trade name Zephiran,is a type of cationic surfactant. It is an organic salt classified as a quaternary ammonium compound. ADBACs have three main categories of use: as a biocide, a cationic surfactant, and a phase transfer agent.ADBACs are a mixture of alkylbenzyldimethylammonium chlorides, in which the alkyl group has various even-numbered alkyl chain lengths. 

Properties

benzalkonium chloride ranges from colourless to a pale yellow (impure). Benzalkonium chloride is readily soluble in ethanol and acetone. Dissolution in water is ready, upon agitation. Aqueous solutions should be neutral to slightly alkaline. Solutions foam when shaken. Concentrated solutions have a bitter taste and a faint almond-like odour.

Uses

Especially for its antimicrobial activity, benzalkonium chloride is an active ingredient in many consumer products:

Pharmaceutical products such as eye, ear and nasal drops or sprays, as a preservative.

Personal care products such as hand sanitizers, wet wipes, shampoos, soaps, deodorants and cosmetics.

Skin antiseptics and wound wash sprays, such as Bactine.

Throat lozenges and mouthwashes, as a biocide.

Spermicidal creams.

Cleaners for floor and hard surfaces as a disinfectant, such as Lysol and Dettol antibacterial spray and wipes.

Algaecides for clearing of algae, moss, lichens from paths, roof tiles, swimming pools, masonry, etc.

Benzalkonium chloride is also used in many non-consumer processes and products, including as an active ingredient in surgical disinfection. A comprehensive list of uses includes industrial applications.An advantage of benzalkonium chloride, not shared by ethanol-based antiseptics or hydrogen peroxide antiseptic, is that it does not cause a burning sensation when applied to broken skin.However, prolonged or repeated skin contact may cause dermatitis.

Toxicity

Benzalkonium chloride is a human skin and severe eye irritant.It is a respiratory toxicant, immunotoxicant, gastrointestinal toxicant, and neurotoxicant.

Benzalkonium chloride formulations for consumer use are dilute solutions. Concentrated solutions are toxic to humans, causing corrosion/irritation to the skin and mucosa, and death if taken internally in sufficient volumes. 0.1% is the maximum concentration of benzalkonium chloride that does not produce primary irritation on intact skin or act as a sensitizer.

Poisoning by benzalkonium chloride is recognised in the literature.A 2014 case study detailing the fatal ingestion of up to 8.1 oz (240ml) of 10% benzalkonium chloride in a 78-year-old male also includes a summary of the currently published case reports of benzalkonium chloride ingestion.While the majority of cases were caused by confusion about the contents of containers, one case cites incorrect pharmacy dilution of benzalkonium chloride as the cause of poisoning of two infants.In 2018 a Japanese nurse was arrested and admitted to having poisoned approximately 20 patients at a hospital in Yokohama by injecting benzalkonium chloride into their intravenous drip bags.

Benzalkonium chloride poisoning of domestic pets has been recognised as a result of direct contact with surfaces cleaned with disinfectants using benzalkonium chloride as an active ingredient.