Bitter mouth, bad breath, dry mouth, yellow teeth, yellow and thick tongue, sticky stool toilet most of them are caused by digestive system diseases. Such as gastric ulcer, gastroenteritis and so on. 1. Gastric ulcer: because the surface of the gastric mucosa is damaged, gastric dynamics is insufficient, food in the stomach indigestion, retention time is too long after the odor will be emitted through the oral cavity, bitter mouth, bad breath, dry mouth, stool sticky toilet, etc., the condition of the long-term ineffective treatment will be manifested in the yellow teeth, yellow tongue, thick. 2. Gastroenteritis: When gastroenteritis is triggered by improper diet, bacterial infection, etc., which leads to imbalance of gastrointestinal flora, reduced secretion of salivary glands, lowered resistance, etc., it will result in bitter taste in mouth, bad taste in mouth, dry mouth, yellow and thick tongue coating, and sticky stool, etc., and in severe cases, it will also result in abdominal pain. It is recommended that patients go to the hospital for relevant examinations and choose the appropriate way of treatment according to their condition. Usually should also eat a light diet, eat more vegetables and fruits as well as crude fiber food, do not eat too greasy food, pay attention to diligent brushing to maintain oral hygiene.