Oral diseases: People suffering from dental caries, gingivitis, periodontitis, oral mucositis and tooth decay, periodontal disease and other oral diseases, their mouths are prone to bacterial growth, especially anaerobic bacteria, the decomposition of which produces sulfide, emitting a corrupt smell and producing bad breath. Gastrointestinal diseases: such as peptic ulcer, chronic gastritis, functional dyspepsia, etc., may be accompanied by bad breath. Recently, we have also found that the incidence of bad breath is significantly higher in those with H. pylori infection, which causes many gastric diseases, than in those without infection, and the symptoms of bad breath are significantly reduced after eradication of H. pylori. The reason for this may be that H. pylori infection directly produces sulfides that cause bad breath. Bad breath not caused by disease: Some patients with metal (e.g., lead, mercury) and organic poisoning have an abnormal odor in their mouths. Consumption of raw onion, raw garlic and certain drugs in the mouth can also produce temporary bad breath. Smokers have a special odor in the mouth, the chemical components of tobacco are absorbed into the bloodstream through the mouth and lungs, and then discharged through the oral and nasal cavities, forming an unpleasant odor. Dieting to lose weight, or due to illness can not eat, or the elderly salivary gland function is reduced, women during menstruation endocrine disorders and lead to reduced saliva secretion, which is conducive to the growth of anaerobic bacteria, so bad breath occurs. Teenage girls bad breath: some women in adolescent development, ovarian function is incomplete, the level of sex hormones is low, the oral tissue resistance is reduced, easy to infect germs and thus produce bad breath. Bad mood can also lead to bad breath: about the relationship between bad breath and emotions, ancestral medicine has long been described. Such as the Qing Dynasty Shen Jinao in the “source of miscellaneous diseases rhinoceros candle” said: “deficiency fire heat, contained in the chest and stomach is bad breath, or labor heart taste thick people also bad breath, or lung for fire burn bad breath. Where the “depression” and “labor of the heart” refers to the bad emotional state of the person. At the same time, Chinese medicine expresses the relationship between the state of mind and the body’s function and the final result of the disease reflected in bad breath.