The main reasons for getting up in the morning with a bitter mouth include oral diseases, gallbladder diseases, stomach diseases and bad habits. If people have a bitter mouth for a long time, it is recommended to go to the regular hospital for further examination, to clarify the cause of the disease, under the guidance of the doctor to treat the cause. 1. Oral diseases: when people suffer from mouth ulcers, periodontitis and other diseases, the morning mouth will appear bitter, pain or bleeding discomfort. 2. Gallbladder diseases: when acute inflammation of the gallbladder is caused by blockage or inflammation of the bile ducts, people will obviously feel bitter in the mouth, dry lips and other uncomfortable symptoms. 3. Gastric diseases: when people suffer from chronic gastritis, bile reflux and other symptoms caused by poor gastric motility will lead to bitter mouth and other uncomfortable symptoms. 4. Bad habits: when people stay up late, alcoholism, spicy and stimulating food that is not easy to digest, it can cause oral cavity, stomach pain, flatulence and other symptoms.