Breath odor is the scent of the air you breathe out of your mouth. Unpleasant, distinctive, or offensive breath odor is commonly called bad breath.
Some disorders will produce specific, characteristic odors to the breath.
A fruity odor to the breath occurs as the body attempts to get rid of excess acetone through the breathing. This is a characteristic sign of ketoacidosis, which may occur in diabetes, and is a potentially life-threatening condition.
A fecal odor to the breath (the breath smells like feces) can occur with prolonged vomiting, especially when there is a bowel obstruction. It may also occur temporarily if a person has a nasogastric tube (a tube placed through the nose or mouth to the stomach to drain the stomach contents) in place.
The breath may have an ammonia-like odor (also described as urine-like or "fishy") in people with chronic kidney failure.
If previously normal breath turns into halitosis, causes could include: