There are many reasons why bad breath smells bad in the mouth, should be dealt with according to the specific causes, common causes of physiological halitosis, as well as pathological halitosis, treatment methods include timely brushing, good oral hygiene, treatment of oral diseases and primary diseases. 1. Physiological bad breath: generally shorter duration, mostly occurring after eating garlic, onion, radish and other foods, or smoking, morning. Taking drugs such as dimethyl sulfide, quinine and antihistamines can also produce transient bad breath. Such brushing can be eliminated. 2. oral disease: according to statistics, most of the bad breath is from oral diseases, such as periodontitis, gingivitis, gingivopapillitis, periodontal abscess, caries, etc., active treatment of oral diseases, good oral hygiene every day, most of the symptoms of halitosis can be greatly relieved. 3. Halitosis can also be seen in non-oral diseases, such as digestive diseases such as reflux esophagitis, gastritis, gastric ulcer, blood system diseases such as aplastic anemia, leukemia, endocrine system diseases such as diabetes mellitus, vitamin C deficiency, renal failure, heavy metal poisoning, etc., such as the need for the primary disease for the appropriate treatment. If the symptoms of bad breath are not eliminated after brushing, you should consult a doctor in time to identify the specific cause with the assistance of a specialist, and then give targeted treatment or therapy.