If the mouth is always overflowing with some liquid, you need to consider the presence of GERD, where gastric juices reflux into the mouth without force or nausea. This condition is often due to decreased pressure on the lower esophageal sphincter and then decreased esophageal clearance, which can cause GERD. In other cases, such as narrowing of the esophagus due to an esophageal tumor, water and food cannot pass through the esophagus and can accumulate in the esophagus, resulting in reflux. These cases need to be clarified by complete gastroscopy. Some GERD patients do not have inflammation in the esophagus and are endoscopically negative for GERD, so they need to have their esophagus pH checked and have their pressure measured to clarify whether reflux exists. In addition to GERD inflammatory conditions in the mouth such as gingivitis, periodontitis and other diseases can also cause excessive drooling in the mouth.