Drooling in adults can be due to physiological and pathological factors. Pathologic causes mainly include: oral diseases, brain diseases, drug factors. 1. Physiological factors: Drooling can be caused when the salivary glands are pressed by improper sleeping positions. If you are too excited during the day, the salivary glands are also prone to secrete more saliva, which will lead to drooling when you sleep with your mouth open to breathe. 2. Oral diseases: For example, patients with mouth ulcers will experience pain and stimulate the glands in the mouth when eating, which in turn leads to drooling. In addition, with thrush, stomatitis and other diseases, due to inflammation stimulation will lead to increased salivary secretion, which will appear drooling. 3. Brain diseases: for example, congenital cerebral hypoplasia, encephalitis, Down’s syndrome and other diseases can affect the nervous system’s regulation of salivary secretion, leading to abnormal salivary secretion, which leads to more saliva secretion and drooling. 4. Drugs: For example, drugs such as clozapine and yohimbine can cause cholinergic nerve excitation, leading to increased salivary secretion, which in turn causes drooling as a side effect. The above are only some of the common reasons. In short, adults drooling situation, must not be careless, if often this symptom, it is recommended to go to the hospital in a timely manner, after a clear diagnosis of standardized treatment in accordance with the doctor’s instructions.