Normal healthy people usually do not have bad breath, the appearance of halitosis may be related to the following reasons: First, oral hygiene is not careful, there are dental caries or periodontitis; Second, the function of the gastrointestinal tract is not good, that is, functional indigestion, after eating some things are always prone to accumulation of food, may be related to this reason; Third, the existence of chronic gastritis, combined with H. pylori infection, this time will also appear bad breath; Fourth, there are some liver, gallbladder disease, such as chronic hepatitis or some inflammation of the gallbladder, will also appear bad breath.