Bitter mouth is not a precursor of cancer. Bitter mouth may be caused by mental factors, oral diseases, liver and gallbladder diseases, gastrointestinal diseases and other factors. 1. Mental factors: If long-term life and work pressure are high, it will easily cause insufficient sleep, which may lead to nerve dysfunction, resulting in bitter mouth. 2. Oral diseases: If you do not eat well or pay attention to oral hygiene, it may lead to periodontitis, dental caries, mouth ulcers and other diseases, which may lead to bitter mouth, bad breath and other symptoms. 3. Liver and gallbladder diseases: Suffering from cholangitis, gallbladder stones, acute cholecystitis and other diseases, due to the decline in gallbladder function or bile duct obstruction, resulting in bile discharge is not smooth, causing bile reflux, bitter mouth. 4. Gastrointestinal diseases: If you often eat late-night snacks or eat late-night snacks too full, you are prone to bile reflux, indigestion, etc., which will easily lead to bitter mouth. Patients with bitter mouth should go to the hospital in time, under the guidance of specialists to clarify the cause of the disease, with appropriate treatment and therapy, and regular follow-up.