It Sounds Crazy But True-Mouthwash May Cause Diabetes & Obesity Mouthwash May Cause Diabetes & Obesity I know it sounds crazy!!! It Kills Good Bacteria! In a 2016 study, researchers found evidence that the popular mouthwash Listerine can control gonorrhea bacteria in people's mouth and throat. While the antibacterial fluid is used to kill harmful oral bacteria, researchers of the new study said that it could also be indiscriminately