Bad breath is a common oral disease, the main causes are poor oral hygiene, long-term accumulation of food residues in the mouth, fermentation and decomposition under the action of bacteria, emitting a rotten bad smell. Some people who wear dentures do not pay attention to the cleaning of dentures, there will also be odor in the mouth, which is the most common cause of bad breath. Oral diseases such as decay in decayed teeth, periodontal diseases such as gum inflammation, abscesses, bleeding, etc. These produce a putrid foul odor. Some bad breath is caused by diseases in other parts of the body, such as dyspepsia, septic bronchitis, lung abscess, etc., which can cause bad odor through the respiratory tract. In addition, diseases of neighboring organs, such as nasopharyngeal and nasal cavity diseases, such as purulent maxillary sinusitis and atrophic rhinitis, can also cause bad breath. Bad breath is a symptom that should not be taken lightly and treated promptly. Do not delay the condition due to negligence.