Benzalkonium chloride (BAK or BAC) is a mixture of chemically similar substances made from animal products and possessing this chemical formula: C?H?-CH?-N?(CH?)?–CnH?n?? Cl?, where n = 8, 10, 12, 14, 16, or 18. It thus possesses the basic structure of ammonium chloride, NH?Cl, substituting a carbonaceous chain for each of the hydrogen atoms. Benzalkonium chloride possesses antimicrobial properties and is suitable for a wide array of uses.
BAK acts as a biocide by interacting with membrane proteins to allow leakage of bacteria cellular contents.
Benzalkonium chloride is both a cationic detergent and an antimicrobial agent. Due to these two characteristics, it is used in everything from hand sanitizers to car-wash products, and is also used as a preservative in opthalmic solutions.
Topically, benzalkonium chloride is used for cold sores and fever blisters.
In embalming, benzalkonium chloride’s primary use is as a disinfecting chemical; however, it is also used as a deodorant.
BAK is used in products such as eye washes and nasal sprays in which it comes into contact with sensitive body tissues. Its safety in some of these products has come under question, but results of inquiries have so far been inconclusive.