There are two factors that cause bitterness in the mouth in the morning: first, local problems in the mouth; second, diseases of the systemic system. Oral local is mainly due to poor oral hygiene, too much bacteria and soft scale on the teeth, resulting in a series of chronic infectious inflammation such as dental caries, gingivitis, periodontitis, pericoronitis of wisdom teeth, oral mucosal ulcers. In this case, the bacteria will release toxins, and the inflammation will have exudation, making the mouth feel bitter when waking up in the morning. From the perspective of traditional Chinese medicine, bitter mouth is a symptom of stomach heat, bile gas inflammation and liver and gallbladder heat, which is common in cases such as gastric ulcer, cholecystitis, gallstone disease and bile reflux, and can be treated with herbs to clear stomach heat and liver and gallbladder, such as Niuhuang Shangqing Pill, Wensha Yangzhi Pill, Xiao Chaihu Tang and Gentian Liver Pill.