Drinking milk and having a bad mouth may be a normal physiological phenomenon caused by gas containing sulfide odor, or it may be caused by other diseases such as gingivitis, pyloric obstruction and gastritis that the patient himself suffers from. 1. gas containing sulfide odor: milk contains protein, calcium and other nutrients, the patient after drinking milk, if you do not clean the mouth in a timely manner, will lead to part of the milk residue in the oral cavity, and the human oral cavity has a variety of bacteria, which will decompose the protein in the milk, resulting in the production of gas containing sulfide odor, resulting in the appearance of the phenomenon of bad breath, is a normal physiological phenomenon. 2. Gingivitis: gingivitis is mainly caused by plaque, the patient will bite hard objects bleeding, gum color dark red, bad breath and other symptoms. If the patient himself suffers from gingivitis, it will also lead to the phenomenon of drinking milk and bad breath. 3. Pyloric obstruction: pyloric obstruction is mainly related to gastroduodenal ulcer and other diseases as well as congenital factors and other factors, the patient’s main symptoms are vomiting, epigastric rumbling, abdominal pain and so on. If the patient suffers from pyloric obstruction, the vomiting will cause the patient to drink milk and have a bad mouth. 4. Other: If the patient suffers from gastritis, periodontitis and other diseases, it will also lead to the performance of the patient’s mouth stinks when drinking milk. When the patient has the symptom of smelly mouth when drinking milk, it may be caused by the gas containing sulfide odor, which does not need treatment. If it is caused by disease, the patient should consult a doctor in time, and follow the doctor’s instructions for treatment.