One of the leading causes of bad breath is bacteria on the tongue. Brush your teeth — and tongue — twice a day to banish bad breath. While you’re brushing your teeth with a fluoride toothpaste, brush your tongue – especially the back of the tongue. Brushing your tongue will remove smelly bacteria that cause bad breath. One study found that by brushing the tongue, volunteers reduced their perception of bad breath by 70%. You can also buy inexpensive tongue scrapers at most pharmacies.