Most of the dry mouth and bitter mouth are caused by fire, which is common in people with strong liver fire, such as long-term tension, anxiety, depression or irritability, these people will often have dry mouth and bitter mouth. If you suffer from diseases of the liver and biliary system, such as bile reflux disease, cholelithiasis, cholestasis, etc., due to the accumulation of bile or even reflux to the inside of the mouth, it will also make the mouth often bitter. Frequent bitterness in the mouth can also be caused by poor digestive system function, which can lead to acid reflux into the mouth. In addition, people whose salivary gland function is impaired, causing a significant decrease in the amount of saliva, will also often cause very serious dry mouth and bitterness.