The causes of bitter mouth and the direction of treatment are as follows: 1. Oral problems, mostly seen in gingivitis and tooth decay, can cause bad breath and bitterness due to oral contamination, which can be treated by taking oral anti-inflammatory drugs or maintaining good brushing habits under the guidance of a dentist. 2. Digestive problems, mostly seen in diseases of the gastrointestinal tract and liver and gallbladder diseases, are the causes of bitter mouth. The cause of bitter mouth, especially in liver and gallbladder diseases, is not only bitter mouth, but also radiating pain in the back of the body and a significantly poorer diet, which can be treated symptomatically by ultrasound examination to clarify the cause of the gallbladder and further application of antibiotics. The disease, if necessary, consider dialysis to correct the function of the kidneys and improve the problem of bitterness in the mouth.