There are many reasons for morning bitterness in the mouth, the most common being oral medication, periodontal and gum lesions, Helicobacter pylori infection, and some diseases in the stomach. Clinically, after taking certain drugs orally, especially the bitter Chinese medicine, the bitter taste in the mouth can be heavier in the morning, which is often caused by drugs, and can be relieved after stopping the drugs for a day or two; in addition, dental calculus, gingivitis, tartar, etc. may also appear the oral odor and bitter symptoms, which can be relieved by scaling and symptomatic treatment; serious bitterness and bad breath are mostly caused by Helicobacter pylori infection, which It can not only induce gastritis and gastric ulcer, but also lead to bad taste in the mouth, which is caused by the continuous reproduction of H. pylori bacteria in the periodontium. In this case, it is recommended to check the C14 respiratory test and take medication according to the results, which can basically relieve the symptoms in one or two courses. There are many reasons for morning bitterness, and the above analysis is only for the common cases, the reasons are too many to be listed.