Bad breath, sometimes called halitosis, is an unpleasant odor of the breath. It is likely to be experienced by most adults at least occasionally. Bad breath, either real or imagined, can have a significant impact on a person's social and professional life.

Bad breath can be caused by a number of problems. Oral diseases, fermentation of food particles in the mouth, sinus infections, and unclean dentures can all contribute to mouth odor. Many non-oral diseases, such as lung infections, kidney failure, or severe liver disease, can also cause bad breath, although this is rare.

Many people think that bad breath originates in the stomach or intestines. This rarely happens. The esophagus is usually closed, and, although a belch may carry odor up from the stomach, the chance of bad breath being caused from air continually escaping from the stomach is remote. Cigarette smoke can cause bad...