Bad breath is usually caused by the breakdown of food in your body. The odors from that process are in your mouth and in your bloodstream and pass through your lungs as you breathe out.
Brushing, flossing and mouthwash only hide bad breath. The bad breath goes away after you go to the bathroom. People who diet sometimes have unpleasant breath. If you don't brush and floss every day, pieces of food remain in your mouth, collecting germs, which can cause bad breath.
Bad breath also may be a sign that you have unhealthy gums. Bad breath is also caused by dry mouth, which happens when you don't have enough saliva, or 'spit,' in your mouth. Saliva is necessary to clean your mouth and remove particles that may cause odor. Bad breath may be the sign of a medical problem, such as an infection in your nose, throat, windpipe, or lungs.
If you brush your teeth and floss every day, you can help to ensure that you at least don't get bad breath from leftover food in your mouth. And remember to see your dentist for regular checkups!