The main causes of drooling include malocclusion, facial nerve damage, and bad habits. When people love to drool for a long time without change, it is recommended to be examined under the guidance of a doctor to clarify the cause of the disease and treat the cause. 1. Malocclusion: When people’s upper and lower front teeth are too protruding or cannot be closed, and the upper and lower lips cannot cover all the teeth, they love to drool while sleeping. It is recommended to correct them as soon as possible under the guidance of professional dentists to avoid delaying the best time for treatment. 2. Nerve damage: When people suffer from peripheral nerve damage or central nerve damage due to diseases (such as brain tumors, cerebrovascular obstruction, etc.), they will experience symptoms such as facial paralysis, drooling, and crooked lips. 3. Bad life habits: people do not like to brush their teeth after eating, poor oral hygiene, over eating spicy and stimulating food, can also cause drooling, bloating, abdominal pain and other symptoms. If the symptoms continue for a long time difficult to relieve, or other discomforts, should promptly seek medical attention.