H. pylori is one of the most direct germs that cause bad breath. Since H. pylori can live in dental plaque, it produces foul-smelling carbons directly after infection in the oral cavity, causing bad breath, etc. H. pylori can decompose urea to produce ammonia and carbon dioxide, which has a special odor; in vitro culture of H. pylori can produce hydrogen sulfide and methanethiol, which are known to cause bad breath; in the presence of H. pylori infection, the gastrointestinal function is impaired, resulting in the retention of food in the gastrointestinal tract for a long time and the decomposition of other bacteria in the gastrointestinal tract to produce a variety of odorous gases. Most of the bad breath caused by H. pylori has no obvious abnormalities in the examination of the oral cavity and is also accompanied by upper abdominal discomfort, periodic pain, eructation, acid reflux, abdominal distension and other stomach symptoms, and C14 is positive for the initial test. Of course not all bad breath must be H. pylori infection, there is also a part of periodontitis, dental caries and other oral problems. H. pylori infection is only one of the factors of bad breath, and not all bad breath, can be attributed to H. pylori infection. Therefore, when you encounter bad breath in the future, you should ask your doctor to make a detailed and comprehensive diagnosis.