Involuntary drooling may be related to physiological factors such as age, or pathological factors such as facial paralysis, cerebrovascular disease, oral ulcers and so on. 1. Physiological factors: infants and young children within 1 year of age may experience involuntary drooling due to small oral volume, large salivary secretion, and gum stimulation from teething. 2. Pathologic factors: (1) Facial paralysis: that is, facial nerve paralysis, mainly due to infection, stroke, inflammation, trauma, tumors, etc., often manifested by crooked mouth, speech leakage, frowning, closed eyes, etc., which will lead to the emergence of involuntary drooling. (2) Cerebrovascular diseases: such as cerebral infarction, etc., will lead to skewed mouth angle, facial paralysis on one side, and involuntary drooling due to central nervous system disorder. At the same time, there will be unfavorable movement of the opposite side of the limbs, slurred speech and other manifestations. (2) Oral ulcers: mainly caused by genetics, diet, immune factors, etc., often showing round ulcer spots on the oral mucosa with obvious pain, which may lead to involuntary drooling. Therefore, there are more causes of involuntary drooling. If the symptoms are serious or accompanied by other symptoms, it is recommended to choose to seek early medical treatment.