If you wake up with a bitter, dry mouth and a foul odor, you may consider that you did not pay attention to oral hygiene and did not brush your teeth before going to bed, resulting in less saliva secretion in the mouth and bacterial growth, and then you wake up with a bitter, dry and foul mouth. Patients are advised to pay attention to oral hygiene and brush their teeth in time to relieve the symptoms. If the symptoms continue to be unable to relieve themselves, they can be considered to be caused by abnormal factors: 1, mental stimulation: patients with poor emotions, tension, anxiety, depression and other adverse emotions, will affect the central nervous system, resulting in less saliva secretion, and then the symptoms of dry mouth, bitterness, bad breath. Patients are advised to relieve their emotions in a timely manner, which can be relieved by watching movies, listening to music, chatting and other entertainment; 2, periodontal disease: is a common oral disease, including gingivitis, periodontitis, etc., is an inflammatory reaction caused by bacterial infection, which can be manifested as tooth sensitivity, oral odor, etc.. It is recommended that patients can go to the hospital for scaling, not only to relieve symptoms, but also to maintain oral hygiene, if necessary, the application of drugs or surgical treatment; 3, indigestion: patients with indigestion, a large amount of food accumulation in the gastrointestinal tract, due to bacterial fermentation will produce ammonia, and then the performance of bitter mouth, bad breath, but also accompanied by constipation, abdominal distension and other symptoms. It is recommended that patients can eat foods rich in dietary fiber, such as celery, apples, bananas, etc., can promote the gastrointestinal tract peristalsis, help digestion, improve the symptoms, but also apply bifidobacteria and other drugs to improve the symptoms.