The Listerine Mouthwash Cool Mint mouthwash is not only antimicrobial and a germ killer, but also a people pleaser. An oral antiseptic, its bold tingle has been America's favorite for years. Just 30 seconds of rinsing, twice a day, is all it takes to reap the benefits of Listerine Mouthwash Cool Mint Antiseptic Mouthwash.