Halitosis is caused by periodontal disease or gastrointestinal disease (mainly indigestion), etc. The effective way to treat it is to carry out periodontal or gastrointestinal disease treatment. 1. Periodontal disease: tartar and calculus can cause gingivitis or periodontitis, the main symptoms of which are bleeding gums and bad breath (i.e., halitosis); the treatment is to go to the doctor for periodontal treatment (e.g., ultrasonic scaling, periodontal scraping, etc.), to remove tartar or calculus and other inflammatory stimulants in order to effectively anti-inflammatory in addition to the bad taste of the oral cavity. 2. Gastrointestinal disease is mainly indigestion will lead to food can not be fully digested and absorbed, and then fermentation produces acidic gases such as exhaust to the oral cavity will produce bad breath symptoms; treatment is to follow the doctor’s instructions to take acid suppression drugs, such as omeprazole, gastric mucosa protection drugs, such as aluminum phosphate, to promote gastric dynamics of the drug, such as domperidone, in order to effectively promote the digestion and absorption of food. When bad breath cannot be improved, it is recommended that patients go to the hospital in time for examination and treatment of the cause.