Seventy-five per cent of cases of facial paralysis in adults are caused by an inflammation of the facial nerve called Bell's palsy. This disorder (probably derived from a virus) is common, affecting 25 out of 100,000 individuals per year. It is more common in people with diabetes. It usually affects one side of the face (very rarely both sides at one time), causing a drooping mouth, drooling, and excessive tearing from one eye.