Bad breath may be periodontal infection, chronic gastritis, reflux esophagitis, diabetes mellitus, cirrhosis of the liver and other causes, for the cause of the appropriate drugs for the fastest good. 1. Periodontal infection: food debris accumulates in the mouth, secondary to bacterial infection, a large number of gram-negative bacteria synthesize and volatilize sulfur compounds, so it will produce bad breath. Eat metronidazole, ceftazidime, azithromycin and other antibacterial drugs to get better fastest. 2. Chronic gastritis: chronic inflammatory lesions of the gastric mucosa lead to weakened digestive function, food stagnation and corruption and produce bad breath. Helicobacter pylori positive patients eat amoxicillin, tetracycline, bismuth pectin, omeprazole and other drugs to get well the fastest. 3. Reflux esophagitis: stomach acid and other stomach contents reflux into the mouth through the esophagus and bad breath. You can eat epprazole, domperidone and other drugs to get the fastest. 4. Diabetes: metabolic disorders in diabetic patients can lead to an increase in the production of ketone bodies, so the mouth appears rotten apple odor. Eat metformin, glipizide, saxagliptin and other hypoglycemic drugs to get the fastest, with eating low-fat low-calorie vegetables, fruits and so on. 5. Cirrhosis: Due to the destruction of liver cells and liver tissues, its function of metabolizing ammonia decreases, resulting in elevated blood ammonia levels and bad breath. You can eat entecavir, tenofovir, diammonium glycyrrhizinate and other drugs, and eat more vegetables and fruits in your diet. It is recommended to go to the hospital in time, and use the medicine under the guidance of the physician.