Bitter morning breath may be associated with oral-related and gastrointestinal-related disorders. 1. Oral-related diseases: patients with dental caries, gingivitis, periodontitis, there is a large number of bacteria in the mouth, the bacteria proliferate and metabolize at night, and their metabolites are fermented overnight, which will produce a bitter taste in the morning, and it is recommended to check and confirm the diagnosis of dental caries patients with filling treatment, gingivitis with gingival cleaning, and periodontitis with periodontal sequential treatment. 2. Gastrointestinal diseases: Gastrointestinal peristalsis, gastroesophageal reflux, cholecystitis and other diseases can cause bitter taste in the morning, of course, these diseases are usually accompanied by other digestive symptoms, it is recommended to go to the Gastroenterology Department for appropriate treatment. It is recommended to go to the stomatology department of regular hospitals for consultation, to be examined by a physician to clarify or exclude oral-related diseases, and then to treat the cause of the disease or referral.