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Bell's palsy is a sudden weakness and paralysis on one side of the face. It is a temporary condition. Bell's palsy can occur in anyone but is most common in people with diabetes or those with a recent cold or flu infection.

Bell's Palsy: Facial Droop

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Bell's palsy is caused by damage to a nerve of the face. The exact cause of this damage is unknown. The damage to the nerve causes swelling along the nerve. The swelling puts extra pressure on the nerve. This extra pressure leads to paralysis of a part of the face.

Some infections are believed to cause some Bell's palsy. Herpes virus, flu virus, and Lyme disease may be associated with Bell's palsy.

Facial paralysis may also be caused by:

• Head or facial injuries
• Tumors
• Diabetes
• Cancer or infection in the cerebrospinal fluid (CSF)
• Strokes
• Abscess
• HIV infection
• Infection
• Autoimmune disease
• Drug therapy, such as chemotherapy
• Hereditary diseases
• Other conditions that cause paralysis of the facial nerve

Factors that may increase your risk of Bell's palsy include:

• Family members who have Bell's palsy
• Pregnancy
• Diabetes
• Cold or flu
• Weakened immune system
• HIV infection
• Smoking
• Hypertension
• Ear infection
• Head or facial trauma
• History of cancer

Bell's palsy symptoms may come on suddenly or develop over a few days. Initial symptoms may include:

• Pain behind the ear that is followed by weakness and paralysis of the face
• Ringing sound in the ears
• Slight fever
• Slight hearing impairment
• Slight increase in sensitivity to sound on the affected side.

Symptoms of full-blown Bell's palsy may include:

• Facial weakness or paralysis (look for smooth forehead and problems smiling)—most often on one side
• Numbness just before the weakness starts
• Drooping corner of the mouth
• Drooling
• Decreased tearing
• Inability to close an eye, which can lead to:
  • Dry, red eyes
  • Ulcers forming on the eye
  • Infection
• Problems with taste
• Sound sensitivity in one ear
• Earache
• Slurred speech

Late complications can occur 3-4 months after onset and can include:

• Long-lasting tightening of the facial muscles
• Tearing from eye while chewing

The doctor will ask about your symptoms and medical history. A physical exam will be done.

Other tests may include:

• Hearing test—to see if nerve damage involves the hearing nerve, inner ear, or hearing mechanism
• Balance test—to see if balance nerves are involved
• Lumbar puncture—a test of the cerebrospinal fluid (CSF) from the lower back; to rule out meningitis, autoimmune disorders, or cancer spreading from a tumor
• Tear test—measures the eye's ability to produce tears
• computed tomography (CT) scan—a type of x-ray that uses a computer to make pictures of structures inside the head to see if there is an infection, tumor, bone fracture, or other problem in the area of the facial nerve
• Magnetic resonance imaging (MRI) scan—a test that uses magnetic waves to make pictures of structures inside the head to see if there is an infection, tumor, bone fracture, or other problem in the area of the facial nerve
• Electrical test (NCM/EMG)—to evaluate for damage to the facial nerve
• Blood tests—to check for diabetes, HIV infection, or Lyme disease

For most, treatment is not needed. Symptoms will often go away on their own within a few weeks. Bell's palsy will completely resolve after a few months in many people. For some people, some symptoms of Bell's palsy may never go away.

If an underlying cause of the Bell's palsy is known, it may be treated. Treatment will be based on that condition.

Some treatments that may be used for Bell's palsy include:

There are no guidelines for preventing Bell's palsy. If you think you are at risk for Bell's palsy, talk to your doctor. There may be steps you can take to reduce your risk.