The first thing to consider when you have bitterness inside your mouth is whether you have internal oral problems such as internal infection as well as ulcers, gingivitis, periodontitis, tongue inflammation, mouth ulcers, etc. The first thing to do is to take care of your mouth, brush your teeth regularly, and if necessary, perform oral cleansing treatment, use mouthwash, etc. If you still have symptoms of bitter mouth, you need to consider the possibility of bile reflux, and further gastroscopy is needed to assess whether there is bile reflux gastritis, as well as sluggishness of the cardia and pylorus, which can cause bile to reflux into the stomach through the duodenum, and then into the esophagus and mouth. If there is a corresponding condition, some biliary medications and medications to promote gastrointestinal motility can be given to treat the situation, and also to treat the corresponding diseases of the gallbladder and bile duct to effectively relieve the symptoms of bile reflux.