Metronidazole tablets can be used to treat bad breath, especially for bad breath caused by anaerobic bacterial infections. Because itself metronidazole as nitroimidazole class of antibiotics, the infection of anaerobic bacteria in the oral cavity, has a better inhibitory effect. And anaerobic bacteria infection in the mouth, anaerobic bacteria often decompose organic substances in the mouth, resulting in the spillage of some odorous gases. From this point of view, metronidazole for bad breath is symptomatic. However, it is important to point out that for halitosis, the application of metronidazole alone to treat it often does not achieve the desired effect. Because there are many causes of bad breath, in addition to the more common clinical anaerobic bacterial infection, including some digestive system diseases, respiratory diseases, and even diabetes, may cause bad breath. For these diseases caused by bad breath, it is necessary to treat the causes of various diseases. Even if the bad breath is caused by anaerobic bacterial infection, metronidazole can only play a suppressive role, but it cannot kill all the anaerobic bacteria. To treat bad breath, in addition to the application of oral medication such as metronidazole, it is also necessary to maintain oral hygiene, and at the same time for the periodontal gingival cleaning or subgingival scraping and other basic cleaning treatment to remove the oral calculus and plaque, so that the anaerobic bacteria have no attachment site, so as to achieve better treatment results.