Rare Infectious Disease News

Disease Profile

Bell’s palsy

Prevalence estimates on Rare Medical Network websites are calculated based on data available from numerous sources, including US and European government statistics, the NIH, Orphanet, and published epidemiologic studies. Rare disease population data is recognized to be highly variable, and based on a wide variety of source data and methodologies, so the prevalence data on this site should be assumed to be estimated and cannot be considered to be absolutely correct.


US Estimated

Europe Estimated

Age of onset





Autosomal dominant A pathogenic variant in only one gene copy in each cell is sufficient to cause an autosomal dominant disease.


Autosomal recessive Pathogenic variants in both copies of each gene of the chromosome are needed to cause an autosomal recessive disease and observe the mutant phenotype.


dominant X-linked dominant inheritance, sometimes referred to as X-linked dominance, is a mode of genetic inheritance by which a dominant gene is carried on the X chromosome.


recessive Pathogenic variants in both copies of a gene on the X chromosome cause an X-linked recessive disorder.


Mitochondrial or multigenic Mitochondrial genetic disorders can be caused by changes (mutations) in either the mitochondrial DNA or nuclear DNA that lead to dysfunction of the mitochondria and inadequate production of energy.


Multigenic or multifactor Inheritance involving many factors, of which at least one is genetic but none is of overwhelming importance, as in the causation of a disease by multiple genetic and environmental factors.


Not applicable


Other names (AKA)

Facial palsy; Facial cranial nerve paralysis; Bell palsy;


Nervous System Diseases


Bell's palsy is a form of temporary facial paralysis which results from damage or trauma to one of the facial nerves. This disorder is characterized by the sudden onset of facial paralysis that often affects just one side and can cause significant facial distortion. Symptoms vary, but may include twitching, weakness, drooping eyelid or corner of the mouth, drooling, dry eye or mouth, impairment of taste, and excessive tearing in the eye. While the exact cause is unknown, many researchers believe that a virus may lead to swelling of the 7th cranial nerve. Steroids, such as prednisone, may reduce the inflammation and swelling.[1][2] Other medications used to treat Bell's palsy include acyclovir (to fight viral infections) and aspirin, acetaminophen, or ibuprofen (to relieve pain).[2] Physical therapy, facial massage and acupuncture have also been used.[1][2]


Because the facial nerve has so many functions and is so complex, damage to the nerve or a disruption in its function can lead to many problems. Symptoms of Bell's palsy, which vary from person to person and range in severity from mild weakness to total paralysis, may include twitching, weakness, or paralysis on one or both sides of the face, drooping of the eyelid and corner of the mouth, drooling, dryness of the eye or mouth, impairment of taste, and excessive tearing in one eye. Most often these symptoms, which usually begin suddenly and reach their peak within 48 hours, lead to significant facial distortion.[3]

Other symptoms may include pain or discomfort around the jaw and behind the ear, ringing in one or both ears, headache, loss of taste, hypersensitivity to sound on the affected side, impaired speech, dizziness, and difficulty eating or drinking.[3]


Bell's palsy occurs when the nerve that controls the facial muscles, the 7th cranial nerve, is swollen, inflamed, or compressed, resulting in facial weakness or paralysis. Exactly what causes this damage is unknown.[1][3]

Many scientists believe that a viral infection such as viral meningitis or the common cold sore virus herpes simplex- causes the disorder when the facial nerve swells and becomes inflamed in reaction to the infection.[2] The disorder has also been associated with influenza or a flu-like illness, headaches, chronic middle ear infection, high blood pressure, diabetes, sarcoidosis, tumors, Lyme disease, and trauma such as skull fracture or facial injury.[3] There may also be an inherited tendency toward developing Bell's palsy.[1]


Some cases of Bell's palsy are mild and do not require treatment.[1][3] In these cases, symptoms may subside on their own within 2 weeks.[3] For those cases that do require treatment, steroids such as prednisone have been used with success to reduce inflammation and swelling. Other medications such as acyclovir --used to fight viral infections -may shorten the course of the disease. Analgesics such as aspirin, acetaminophen, or ibuprofen may relieve pain. Because of possible drug interactions, patients should always talk to their doctors before taking any over-the-counter medicines. Keeping the eye moist and protected from debris and injury is important. Other therapies such as physical therapy, facial massage or acupuncture may also be used.[2][3] In general, decompression surgery for Bell's palsy is controversial and is seldom recommended.[3]

Learn more

These resources provide more information about this condition or associated symptoms. The in-depth resources contain medical and scientific language that may be hard to understand. You may want to review these resources with a medical professional.

Where to Start

In-Depth Information

  • Medscape Reference provides information on this topic. You may need to register to view the medical textbook, but registration is free.
  • The Monarch Initiative brings together data about this condition from humans and other species to help physicians and biomedical researchers. Monarch’s tools are designed to make it easier to compare the signs and symptoms (phenotypes) of different diseases and discover common features. This initiative is a collaboration between several academic institutions across the world and is funded by the National Institutes of Health. Visit the website to explore the biology of this condition.
  • Orphanet is a European reference portal for information on rare diseases and orphan drugs. Access to this database is free of charge.
  • PubMed is a searchable database of medical literature and lists journal articles that discuss Bell's palsy. Click on the link to view a sample search on this topic.


  1. Bell's Palsy. National Organization for Rare Disorders (NORD). 2005; https://rarediseases.org/rare-diseases/bells-palsy/.
  2. NINDS Bell's Palsy Information Page. National Institute of Neurological Disorders and Stroke (NINDS). April 16, 2015; https://www.ninds.nih.gov/disorders/bells/bells.htm.
  3. Bell's Palsy Fact Sheet. National Institute of Neurological Disorders and Stroke (NINDS). April 16, 2015; https://www.ninds.nih.gov/disorders/bells/detail_bells.htm.

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