Cool Mint Listerine Mouthwash 1.5 Liter Bottle. Listerine was shown in a clinical study to reduce 52% more plaque and 21% more gingivitis than brushing and flossing alone. Listerine is the only nationally branded antimicrobial mouthwash to receive the ADA Seal of Acceptance for fighting plaque and gingivitis. 1.5 liter bottle