Dry and bitter mouth can be caused by oral diseases or gastrointestinal diseases. If the mouth suffers from gingivitis, periodontitis or periapical periodontitis, dental caries, pulpitis and other diseases, it will lead to overgrowth of bacteria in the mouth, resulting in the feeling of dry mouth and bitter mouth. And with age, due to the weakening of salivary gland secretion, dry mouth may also occur, coupled with inflammation in the mouth will appear bitter mouth discomfort. In addition, if there is a problem with the digestive system, suffering from gastrointestinal disorders, such as gastric ulcers or gastritis and other diseases, can also lead to dry mouth and bitter mouth. When it comes to the symptoms of dry mouth and bitterness, it is best to seek medical attention to figure out what is causing the symptoms and then treat the cause.