Cetylpyridinium chloride (CPC), a cationic quaternary ammonium compound, is used in certain classes of throat sprays, mouthwashes, lozenges, toothpaste, nasal sprays, and breath sprays. Cetylpyridinium chloride has also been used as an ingredient in certain pesticides. It is an antiseptic with killing bacteria and other microorganisms. It can be potent in reducing gingivitis and preventing dental plaque. It may result in brown stains between the teeth and on the surface of teeth.