Bitter mouth in the morning may be considered as bile reflux. Bile is bitter, which is often referred to as bitter bile. Bile is secreted by the liver, passes through the left and right hepatic ducts, and then goes to the gallbladder and is stored there. When the eaten food reaches the stomach and then goes down to reach the duodenum, bile is excreted from the gallbladder again and reaches the duodenum through the common bile duct to digest food as digestive juices. Usually, the bile then follows the food, down the duodenum to the jejunum below, and in some cases may reflux to the stomach then to the esophagus and then to the mouth, resulting in the symptom of bitter mouth. This is associated with certain diseases of the biliary tract, post cholecystectomy, reduced gastrointestinal motility, etc. In addition, if the function of the pylorus and cardia of the stomach is weakened and loses its original function of blocking food and bile reflux, the symptoms of bitterness in the mouth also tend to appear. First, treatment should be provided for these diseases. Secondly, it is necessary to improve dietary habits, reduce the intake of high-fat food, try to eat easily digestible food, eat less and more meals, try not to lie flat after eating food, and consider taking a walk for 1-2 hours to bile to reduce bile reflux. If you have the habit of eating late night snacks before going to bed, you must quit, because if you eat food before going to bed, it will easily lead to reflux of bile when you sleep, and thus you will have the symptoms of bitter mouth in the morning. If the symptoms are still severe, you need to take medication to reduce the bitter mouth symptoms of bile reflux.