Bell's palsy is a condition characterized by sudden, temporary weakness or paralysis of the facial muscles, typically affecting one side of the face. This condition results from inflammation or compression of the facial nerve (cranial nerve VII), which controls the muscles of facial expression. The exact cause of Bell's palsy is unknown, but it is often linked to viral infections such as herpes simplex, which causes cold sores.

Symptoms of Bell's palsy can vary but usually include a rapid onset of mild weakness to total paralysis on one side of the face, making it difficult to close the eye, smile, or wrinkle the forehead on the affected side. Other symptoms may include drooping of the mouth, drooling, altered taste, increased sensitivity to sound in one ear, and pain around the jaw or behind the ear.

Treatment for Bell's palsy aims to reduce inflammation and promote recovery of the facial nerve. Common treatments include corticosteroids to decrease inflammation, antiviral medications if a viral infection is suspected, and physical therapy exercises to stimulate facial muscles and prevent muscle contractures. Protecting the eye on the affected side from drying out by using lubricating eye drops or wearing an eye patch is also important if eyelid closure is compromised.

Most individuals with Bell's palsy begin to recover within a few weeks to a few months, and the majority regain normal or near-normal facial function. Early treatment and intervention can improve the likelihood of a full recovery.