Bell's palsy is an unexplained episode of facial muscle weakness or paralysis. It begins suddenly and worsens over 48 hours. This condition results from damage to the facial nerve (the 7th cranial nerve). Pain and discomfort usually occur on one side of the face or head.

Bell’s palsy can strike anyone at any age. It occurs most often in pregnant women, and people who have diabetes, influenza, a cold, or another upper respiratory ailment. Bell's palsy affects men and woman equally. It is less common before age 15 or after age 60.

The main symptoms are disordered movement of the muscles that control facial expressions, such as smiling, squinting, blinking, or closing the eyelid. You may also notice; headaches, tearing, drooling, loss of the sense of taste on the front two-thirds of the tongue, hypersensitivity to sound in the affected ear (hyperacusis) and/or inability to close the eye on the affected side of the face.