Paralysis causes a sudden and temporary weakness of the facial muscles. This will allow half of your face to work. His smile is one-sided and his eye on this side does not close. Paralysis of the bell, also called facial paralysis, can occur at any age. The exact cause is unknown. This is thought to be due to the swelling and inflammation of the nerve that controls the muscles on one side of the face. Or it can be a reaction that occurs after a viral infection. For most people, Bell's palsy is temporary. Symptoms usually begin to subside after a few weeks and recovery takes about six months. A small number of people still have symptoms of Bell's palsy. Rarely, Bell's palsy can reappear.