Halitosis is not necessarily Helicobacter pylori infection, gingivitis, dental caries and other diseases in a variety of oral bacterial infections can lead to patients with symptoms of halitosis, in addition, liver failure, diabetic ketoacidosis and other diseases can also lead to patients with bad breath. 1. Helicobacter pylori infection: Helicobacter pylori infection can lead to symptoms of halitosis, in addition, the patient will also appear epigastric discomfort, abdominal distension, nausea, belching, vomiting, black stool, anemia and other symptoms. 2. Oral bacterial infections: oral bacterial infections can lead to gingivitis, dental caries and other diseases, which can also lead to symptoms of bad breath, in addition, the patient can also appear gums redness, swelling, bleeding, tooth color changes, dental tissue defects and other changes. 3. Metabolic factors: liver failure patients due to liver clearance of methionine intermediate products of methyl mercaptan and dimethyl sulfide function is reduced, so the symptoms of bad breath; diabetic ketoacidosis patients due to excessive fat decomposition, so the fat metabolism products of acetone through the respiratory discharge, which can be the symptoms of halitosis. In addition to the above factors, other causes can also lead to bad breath symptoms, it is recommended to consult a doctor in time to identify the cause and ask the doctor to deal with it.