Halitosis is categorized into exogenous and endogenous halitosis. Exogenous halitosis can be eliminated by cleaning the mouth, filling and periodontal treatment, while endogenous halitosis requires treatment of systemic diseases. 1. Exogenous bad breath: bad breath may be caused by poor oral hygiene and fermentation of food residues, which requires careful brushing and cleaning of the oral cavity. If it is caused by dental caries, it is necessary to grind the decayed tooth tissue and resin fillings. If it is caused by periodontal inflammation, you need to do periodontal treatment to eliminate inflammation of the gums, and if it is tonsil stones, you need to remove the tonsil stones. 2. Endogenous bad breath: endogenous bad breath is common in digestive diseases such as gastric ulcer, or respiratory diseases such as bronchitis, need to be combined with the diagnosis of internal medicine physician using drugs (omeprazole, azithromycin) or surgical treatment. Halitosis should first check the source of odor, and then targeted treatment, drugs need to follow the doctor’s instructions for rational application.