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Patient education: Bell's palsy (Beyond the Basics)

Michael Ronthal, MD
Section Editor
Jeremy M Shefner, MD, PhD
Deputy Editor
John F Dashe, MD, PhD
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Bell's palsy is a condition in which the nerve that controls the muscles of the face becomes injured or even stops working altogether. This causes the facial muscles to become weak or paralyzed. Common signs of Bell's palsy are weakness of muscles on one side of the face, drooping eyelid or mouth on one side, or drooling from one side of the mouth (picture 1).

Bell's palsy affects about 40,000 people each year in the United States, affecting all races and both genders equally. Diabetes and pregnancy increase the risk of developing Bell's palsy.

Most people with Bell's palsy recover completely. A minority of people continue to have some symptoms for life. If you have any signs of Bell's palsy, you should see a doctor or nurse because treatment is available, but should be started within two to three days of onset. More detailed information about Bell's palsy is available by subscription. (See "Bell's palsy: Pathogenesis, clinical features, and diagnosis in adults" and "Bell's palsy: Treatment and prognosis in adults".)


Bell’s palsy is caused by an inflammation of the facial nerve. This inflammation may be caused by a virus. There is some evidence that the virus is often herpes simplex virus (HSV), the same virus that causes cold sores and genital herpes. Other viruses may also cause the condition, including herpes zoster virus, cytomegalovirus, and Epstein-Barr virus. (See "Patient education: Genital herpes (Beyond the Basics)" and "Patient education: Shingles (Beyond the Basics)".)

The inflammation causes swelling of the nerve that controls movement of one side of the face. The nerve, as well as tiny blood vessels near the nerve, must travel through a narrow canal surrounded by bone. As the nerve swells, it becomes compressed (pinched) and its protective covering breaks down, interfering with the nerve's ability to communicate with the muscles. This causes weakness or paralysis of the muscles in one side of the face. Weakness of these muscles can make it difficult to smile or close the eye.


Bell's palsy causes one side of the face to be partly or completely paralyzed. This may cause:

Eyebrow sagging

Drooping of the eye and corner of the mouth

One eye will not close completely (picture 1)

In some cases, you may lose the normal ability to close one eye, which can lead to drying of the surface of the eye (the cornea). Loud noises may cause discomfort in the ear on the affected side — a condition called hyperacusis. In addition, some people lose the sense of taste on the front of the tongue.

The changes caused by Bell's palsy will affect the appearance of your face, including how you smile. These changes are often obvious to others, and can cause people with Bell's palsy to feel distressed and to avoid social activities.

The symptoms of Bell's palsy usually appear over a period of a day or two. Most patients begin to improve within three weeks after the first symptoms begin. Improvement may continue for three to six months.


Bell's palsy is usually diagnosed based on your symptoms and a physical examination. Blood and other tests are not usually needed, but doctors often test for Lyme disease, a treatable infection that can cause weakness of the face.


There is no cure for Bell's palsy, but treatment can help you to get better faster, especially if you can start treatment within the first few days. However, you may not have to be treated for Bell's palsy if your symptoms are mild. Talk to your doctor or nurse to ask if you should be treated.

Eye care — You will need eye treatments if you cannot close your eye. If the cornea, which is the clear protective covering of the pupil, becomes overly dry, there is a risk of permanent eye damage. You can use artificial tears (eye drops) as often as every hour during the day to keep the eye moist. A moisturizing ointment is usually better at night. You can use the ointment during the day, although it will make your vision blurry.

If your eye does not close completely, you should protect it during the day with glasses or goggles. Use a patch over your eye at night, but be sure not to use tape on your eyelid since the patch could slip and scratch the cornea.

Medications — Most people who are diagnosed with Bell's palsy (within two to three days of the first symptoms) are treated with steroids (eg, prednisone) for one week. Steroids, also called glucocorticoids, can reduce swelling and improve your chances of recovering completely. These medicines work best when started early (within three days of the first symptoms). Antiviral medicines (eg, valacyclovir, Valtrex) are sometimes used in conjunction with glucocorticoids, especially when the facial weakness is severe. Some controlled trials have found an added benefit from the use of these agents in patients with very severe facial paralysis. Other forms of treatment are unproven.

Facial nerve palsy caused by Lyme disease is treated with antibiotics. Steroids can be used with antibiotics, but there is no proof that steroids are of benefit when Lyme disease is the cause of the facial weakness. (See "Patient education: Lyme disease (The Basics)" and "Treatment of Lyme disease", section on 'Facial nerve palsy'.)

Monitoring — You will need a follow up visit with your doctor or nurse after you start treatment. At this visit, you will have an examination and you can discuss any questions or problems.


In general, people whose paralysis is less severe tend to recover more completely. If symptoms begin to improve within the first 21 days, the chances are also good that you will recover and have little or no remaining weakness in the muscles of the face. However, a small number of people are left with moderate to severe muscle weakness that is permanent. (See "Bell's palsy: Treatment and prognosis in adults".)

If the damage to the nerve is severe, it may heal and grow back in a disorganized fashion. When this happens, your ability to control separate facial movements may be lost. For example:

When you blink your mouth may twitch

Smiling may cause your eye to close

When you salivate (eg, before eating), tears may flow from one eye

A second or third attack of Bell's palsy is uncommon, but has been reported in 7 to 15 percent of people.


Your healthcare provider is the best source of information for questions and concerns related to your medical problem.

This article will be updated as needed on our web site (www.uptodate.com/patients). Related topics for patients, as well as selected articles written for healthcare professionals, are also available. Some of the most relevant are listed below.

Patient level information — UpToDate offers two types of patient education materials.

The Basics — The Basics patient education pieces answer the four or five key questions a patient might have about a given condition. These articles are best for patients who want a general overview and who prefer short, easy-to-read materials.

Patient education: Bell's palsy (The Basics)
Patient education: Stroke (The Basics)
Patient education: Myasthenia gravis (The Basics)

Beyond the Basics — Beyond the Basics patient education pieces are longer, more sophisticated, and more detailed. These articles are best for patients who want in-depth information and are comfortable with some medical jargon.

Patient education: Genital herpes (Beyond the Basics)
Patient education: Shingles (Beyond the Basics)

Professional level information — Professional level articles are designed to keep doctors and other health professionals up-to-date on the latest medical findings. These articles are thorough, long, and complex, and they contain multiple references to the research on which they are based. Professional level articles are best for people who are comfortable with a lot of medical terminology and who want to read the same materials their doctors are reading.

Bell's palsy: Pathogenesis, clinical features, and diagnosis in adults
Bell's palsy: Treatment and prognosis in adults
Clinical manifestations of Lyme disease in adults

The following organizations also provide reliable health information:

National Library of Medicine

National Institute of Neurological Disorders and Stroke

AAO-HNS American Academy of Otolaryngology – Head and Neck Surgery

Literature review current through: Nov 2017. | This topic last updated: Thu Jul 06 00:00:00 GMT+00:00 2017.
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