Bell's palsy is also known as “acute facial palsy of unknown cause.” It’s a condition in which the muscles on one side of your face become weak or paralyzed. It affects only one side of the face at a time, causing it to droop or become stiff on that side. It’s caused by some kind of trauma to the seventh cranial nerve. This is also called the “facial nerve.” Bell’s palsy can happen to anyone. But it seems to occur more often in people who have diabetes or are recovering from viral infections. Most of the time, symptoms are only temporary. A few people don’t recover fully and are left with some weakness or paralysis of the muscles on that side of their face.