Bad breath is not contagious, but people with bad breath usually have oral inflammation and bacterial infections, and if there is much contact with such patients, the chances of bacterial infections are high, and the probability of oral diseases will increase. Bad breath is sometimes caused by mental factors, and it is likely to be mistakenly thought that you have bad breath, and so you keep such worries in your mind, which is also not good for your health. Regardless of the cause of bad breath, first check the state of oral hygiene, whether to pay attention to oral hygiene, whether there is periodontal disease, if there is indeed a disease should be actively treated. Gingivitis, periodontitis and other diseases can be oral metronidazole, bacterial infection is serious can then add antibiotics, so that the combination of drugs will certainly have an effect, must pay attention to brushing, rinsing, carefully maintain oral hygiene, drink more green tea, all the bad breath can be relieved.