Getting up in the morning with a slightly bitter mouth may be caused by liver and gallbladder diseases, gastrointestinal diseases or oral diseases. 1. Liver and gallbladder diseases: when there is hepatitis, cholecystitis, gallstones and other diseases can cause bile secretion abnormalities, resulting in the phenomenon of bitter mouth, after diagnosis, you can follow the doctor’s instructions to use anti-inflammatory cholecystolithiasis tablets and other drugs to treat. 2. Gastrointestinal diseases: if there is esophageal reflux gastritis and other reasons, can also cause bitter mouth phenomenon, you can use omeprazole, rabeprazole sodium and other drugs. 3. Oral disease: if you do not pay attention to oral hygiene or eat sweets, can cause dental caries, gingivitis, periodontitis and other diseases, resulting in the phenomenon of bitter mouth, you can use metronidazole and other drugs to treat, if necessary, tooth extraction and so on. The above are only some of the common causes. If the symptoms persist or recur, you should consult a doctor. After a clear diagnosis, follow the doctor’s instructions to standardize the treatment. The use of the above drugs must follow the doctor’s advice, not blindly use their own medicine, so as not to cause adverse consequences.