If you have bad breath, go to the hospital to see the stomatology, ear, nose and throat, gastroenterology, and endocrinology departments. The appearance of bad breath is related to many factors, and the choice of department is different for different reasons. Some people have bad breath accompanied by swollen and painful gums, bleeding gums and other symptoms, most of which are caused by oral diseases, so they need to go to the stomatology department of the hospital for examination and treatment of dental diseases. Some people have bad breath due to rhinitis, sinusitis or other diseases, and these people need to go to the ENT department of the hospital for examination. When bad breath is accompanied by nausea, vomiting, indigestion and abdominal pain, most of them are caused by gastrointestinal diseases, such as stomach fire, Helicobacter pylori infection and gastric neurosis, and these people need to go to the gastroenterology department for examination. Patients with diabetes mellitus have an endocrine disorder and therefore produce acetone, which causes a sour taste in the mouth, and these people need to go to endocrinology for treatment.