Foul mouth, i.e., halitosis, requires active medical examination and, depending on whether it is a source of halitosis, oral specialty treatment or medication, etc., respectively. There are many causes of bad breath, and it is necessary to actively seek medical examination to clarify the cause of the disease, so as to carry out targeted treatment: 1. Halitosis of oral origin: oral specialty treatment. (1) bad breath caused by periodontitis, need to carry out periodontal sequence treatment, including scaling, scraping, local rinsing and medication. (2) Halitosis caused by dental caries and pulpitis requires caries filling treatment and root canal treatment. (3) Bad breath caused by residual roots and defective restorations requires extraction of residual roots and removal of defective restorations. 2. Non-oral halitosis: medication is the main treatment. (1) It is bad breath caused by Helicobacter pylori infection, common drugs include proton pump inhibitors such as omeprazole, amoxicillin, metronidazole and other antimicrobial drugs, as well as bismuth composed of quadruple therapy. (2) If the bad breath is caused by systemic diseases, such as diabetes mellitus, common drugs are metformin, insulin, etc.. (3) If it is a patient with mental illness who is self-conscious about halitosis, it is recommended to have psychological counseling or take relevant psychotropic drugs such as chlorpromazine, etc.. Specific medication needs to be taken under the guidance of a doctor.