Bells palsy is a sudden weakness or paralysis on one side of the face, which is caused by inflammation or damage to the facial nerve. The exact cause of Bells palsy is unknown, but it is thought to be due to swelling and inflammation of the nerve that controls the muscles on one side of the face. It could be caused by a reaction that occurs after a viral infection. Some viruses that have been linked to Bells palsy include viruses that cause:

• Herpes simplex 1 (a virus that causes mouth infections, like cold sores)
• Varicella-zoster virus (chickenpox and shingles)
• Epstein-Barr virus (mononucleosis)
• COVID-19

Bells palsy can also be associated with other conditions such as diabetes, high blood pressure, injury, toxins, Lyme disease, Guillain-Barré syndrome, sarcoidosis, myasthenia gravis, and multiple sclerosis. Bells palsy can occur at any age, but it occurs most often in pregnant women and people who have diabetes, influenza, a cold, or another upper respiratory ailment.