Bell’s palsy is a temporary paralysis or weakness that usually occurs on one side of the face when there is damage to facial nerves. The condition may also be referred to as acute idiopathic facial palsy or Bell’s palsy syndrome.

Bell’s palsy is the most common cause of facial paralysis. The paralytic symptoms may begin suddenly and peak within 48 hours. Most patients improve gradually and their symptoms diminish or disappear within two weeks. Some may experience the effects for six months to a year. A few people may experience permanent facial muscle shrinkage and a distorted appearance, such as an asymmetric smile that curves up on one side and down on the other.

The affected areas may start at the forehead and stretch down to the chin and over to the ear, usually on one side of the face. This can cause the mouth and affected eyelid to droop and sag. The ability to blink may be hindered to the point that the eye dries out from lack of lubrication. Dryness makes the eyes more susceptible to injury or infection. Debris can more easily fly into the eyes, making them more vulnerable to injury. Drooling and slurred speech can also occur. Some people may experience hearing loss or hypersensitivity to sound on one side.

The causes of Bell’s palsy are not well understood. Viral infections, such as the herpes viruses that cause cold sores and shingles may be involved. The viruses may cause inflammation and pressure along the facial nerve, contributing to the paralysis. For some people, the facial palsy may be preceded by influenza or respiratory illness. Other causes may include facial trauma, such as from an automobile accident or sports injury.

Treatment for Bell’s palsy depends on the cause of the facial nerve damage. Antiviral medications and corticosteroids may be prescribed to fight infection and inflammation and pain relievers may be taken for jaw, ear or mouth pain that may accompany the paralysis. However, even after a patient fully recovers, there can be a relapse. One in five patients has recurrences of facial palsy.