Bitter mouth may be caused by bad habits, digestive diseases, oral diseases, systemic diseases, etc. Further examination is needed to confirm. 1. Bad habits: irregular work and rest, excessive alcohol consumption, irregular diet, overeating, addiction to alcohol and tobacco, or stay up late, stress, etc., may lead to bitter mouth. 2. Digestive diseases: gastritis, gastrointestinal dysfunction, Helicobacter pylori infection, as well as bile reflux, cholecystitis, gallbladder stones and other digestive disorders can lead to bitter mouth. 3. Oral diseases: chronic periodontitis often presents with swollen and painful gums, bitter mouth, bad breath, bleeding gums and so on. 4. Systemic diseases: diabetes, uremia, etc. can also appear bitter mouth symptoms. If you find a long-term bitter mouth, it is recommended to consult a doctor in a timely manner, follow the doctor’s instructions for examination and treatment. In addition, bitter mouth patients usually pay attention to good oral hygiene, and develop the habit of rinsing after eating.