Listerine is a brand of antiseptic mouthwash that is promoted with the slogan "Kills germs that cause bad breath". Named after Joseph Lister, who pioneered antiseptic surgery at the Glasgow Royal Infirmary in Scotland, Listerine was developed in 1879 by Joseph Lawrence, a chemist in St. Louis, Missouri.

Mouthwash, mouth rinse, oral rinse, or mouth bath is a liquid which is held in the mouth passively or swirled around the mouth by contraction of the perioral muscles and/or movement of the head, and may be gargled, where the head is tilted back and the liquid bubbled at the back of the mouth.