Bell's palsy is a condition that causes sudden, temporary weakness or paralysis of the muscles on one side of the face. It occurs when the facial nerve, which controls facial expressions, becomes inflamed. The exact cause is often unknown, but it may be linked to viral infections. Symptoms of Bell's palsy can include drooping of one side of the face, difficulty closing the eye, and changes in taste. Most people recover fully within weeks to months, although some may experience lingering effects. Treatment options may include medications to reduce inflammation and physical therapy to improve muscle function.