Bell’s palsy, also known as facial palsy, is a condition that causes sudden weakness in the facial muscles. It makes the face appear droopy while the smile is one-sided and the eye on the affected side resists closing.

The exact cause is undetermined; however, it may be the result of swelling and inflammation of the nerve that controls the muscles on one side of the face. It also may occur as a reaction to a viral infection. In rare cases facial palsy can affect the nerves on both sides of the face.

Bell’s palsy is usually temporary with complete recovery in approximately 6 months. In rare cases the condition can recur or cause lifelong symptoms.


Symptoms of Bell’s palsy include:

  • Sudden onset of weakness to total paralysis on one side of the face (within hours to days)
  • Facial droop and difficulty making facial expressions
  • Drooling
  • Pain around the jaw or in or behind the ear on the affected side
  • Headache
  • Decreased ability to taste
  • Increased sensitivity to sound on the affected side
  • Variations in the amount of tears and saliva produced


The exact cause of Bell’s palsy is unknown but it is often associated to exposure to a viral infection. Viruses related to Bell’s palsy include:

  • Herpes simplex (cold sores and genital herpes)
  • Herpes zoster (chickenpox and shingles)
  • Epstein-Barr (mononucleosis)
  • Cytomegalovirus infections
  • Rubella (German measles)
  • Adenovirus (respiratory disease)
  • Mumps virus (mumps)
  • Influenza B (flu)
  • Coxsackie virus (hand, foot and mouth disease)

Risk factors

Risk factors for Bell’s palsy include:

  • Pregnancy (during the third trimester or in the first week after childbirth)
  • Diabetes
  • Upper respiratory infection (flu or the cold)
  • Genetic predisposition (recurrent episodes of Bell’s palsy can be the result of family history of the condition)


Complications that arise from Bell’s palsy include:

  • Irreversible damage to the facial nerve.
  • Partial or complete blindness of the eye on the affected side due to excessive dryness and scratching of the cornea.
  • Misdirected regrowth of nerve fibers that can cause synkinesis (involuntary contraction of certain muscles when trying to move others).