It’s a myth that mouthwash cures bad breath. Mouthwash causes bad breath by drying out the mouth. Mouthwash is full of alcohol – up to 25% alcohol in some brands, which is more than beer! Alcohol dries out the mouth which exacerbates bad breath because saliva is what disorganizes bacteria in the mouth. Saliva maintains a healthy pH in the mouth and ensures that certain types of bacteria don’t propagate.