The flow of un-swallowed saliva from the mouth, normal in children up to about age 1. In babies 3 to 4 months old, more saliva is produced than can be swallowed. Excessive drooling becomes even more common during teething. Most children no longer drool after the age of 4 years. Children who have neurological problems may drool because they have difficulty controlling the muscles and nerves involved in swallowing. Certain adult disorders such as Parkinson disease and facial paralysis can cause drooling. Poor-fitting dentures also can result in drooling.