Stearalkonium chloride is a type of benzalkonium chloride

Benzalkonium chloride

Benzalkonium chloride, also known as alkyldimethylbenzylammonium chloride and ADBAC, is a mixture of alkylbenzyldimethylammonium chlorides of various even-numbered alkyl chain lengths. This product is a nitrogenous cationic surface-acting agent belonging to the quaternary ammonium group...

 which is used as an anti-static agent, a surfactant

Surfactant

Surfactants are compounds that lower the surface tension of a liquid, the interfacial tension between two liquids, or that between a liquid and a solid...

 and an antimicrobial

Antimicrobial

An anti-microbial is a substance that kills or inhibits the growth of microorganisms such as bacteria, fungi, or protozoans. Antimicrobial drugs either kill microbes or prevent the growth of microbes...

. It is an ingredient in some cosmetics and hair care products, particularly conditioners

Hair conditioner

Hair conditioner is a hair care product that alters the texture and appearance of hair.-History:For centuries, natural oils have been used to condition human hair. These natural products are still used today, including essential oils such as tea tree oil and carrier oils such as jojoba oil...

.

Toxicology studies have determined that stearalkonium chloride is safe and non-toxic at the concentrations typically used in cosmetic products (0.1 to 5%). At higher concentrations (25% solution), it has been shown to be a skin and eye irritant in animal studies.