- Used twice daily, LISTERINE® Cool Mint provides 24-hour protection against plaque. - It has clinically proven ingredients to prevent & reduce plaque, a major cause of gum disease. - It gives lasting fresh breath confidence and kills 99.9% of bacteria in lab tests. LISTERINE® Cool Mint Mouthwash for a cleaner fresher mouth than brushing alone. The formula removes up to 99% of bad breath and plaque causing germs left after brushing.