Overview
Bell's palsy is a sudden weakness or loss of movement in the muscles on one side of the face. It happens when the facial nerve, which controls the muscles of the face, becomes inflamed and swollen. It is the most common cause of facial paralysis.
It is not a stroke, but a stroke can look the same at first. Most people get better, usually within weeks to months, although some are left with lasting weakness.
Symptoms
Symptoms appear over a few days and are usually at their worst after about two days. Most often only one side of the face is affected. They can include:
- A drooping mouth or eyelid on one side
- Weakness, or being unable to move one side of the face
- Trouble closing the eye on the affected side
- Drooling, and trouble eating or drinking
- A dry mouth, or a dry or watering eye
- A change in taste, or sounds that seem louder in one ear
- Discomfort around the ear
When to see a doctor
Even when a doctor has said it is Bell's palsy, get advice as early as possible, because treatment works best when started within 72 hours. See a doctor again if there is no improvement after 3 weeks, if the eye will not close or becomes sore, or if you feel low or anxious.
Causes
The exact cause is often not known. Doctors think a viral infection, such as a herpes virus, makes the facial nerve swell as it passes through the skull. Other conditions that can affect the nerve include Lyme disease, HIV, middle ear infections and sarcoidosis, so a doctor may check for these.
Risk factors
- Diabetes
- Pregnancy
- A recent cold or flu
Complications
Most people recover well. Possible problems include:
- A dry, irritated eye that cannot close, which can damage the clear front of the eye (the cornea) and, if untreated, harm vision
- Lasting weakness of the face
- Pain around the jaw or behind the ear, a constantly watering eye, or changes in taste
- Twitching or spasms of the face or eyelid
- Low mood, stress or anxiety
- Rarely, Bell's palsy coming back, sometimes years later
Prevention
Because the cause is not fully understood, there is no sure way to prevent Bell's palsy. Keeping diabetes under control is worthwhile anyway, as diabetes is linked with a higher risk.
Diagnosis
A doctor can often diagnose Bell's palsy from your story and by examining your face, and must make sure it is not a stroke. Tests may be used when the picture is unusual:
- Blood tests, for example to look for Lyme disease
- Nerve and muscle tests (EMG and nerve conduction studies)
- A CT or , or a spinal tap, if another cause is suspected
Treatment
A short course of steroid medicine is often given, sometimes with an antiviral medicine. It works best when started early. Some people need no treatment and begin to improve within days, although the muscles can take weeks to months to recover.
Protecting the eye matters. If it will not close, a doctor may advise lubricating eye drops by day, an ointment at night, and tape or a patch to keep the eye closed during sleep. Surgery to relieve pressure on the nerve has not been shown to help most people.
Myths and facts
Things people often say about this. Open each one to see what is true.
Myth“Bell's palsy is caused by cold air from a fan, cooler or AC, or by sleeping near an open window.”What is true?
Fact
Health bodies describe Bell's palsy as swelling of the facial nerve, thought to be caused by a viral infection. A draught is not named as a cause. A recent cold or flu, diabetes and pregnancy are linked with a higher risk.
Myth“If the face droops, it is a stroke and the person will stay paralysed.”What is true?
Fact
A sudden droop of the face must be treated as a possible stroke until a doctor says otherwise, because a stroke is an emergency. But Bell's palsy affects only the face, and most people recover fully within weeks to months.
Myth“It will go away by itself, so there is no need to see a doctor.”What is true?
Fact
Many people do improve without treatment, but a doctor needs to make sure it is not a stroke and to protect the eye. Steroid medicine works best when it is started early, within 72 hours, so do not wait.
Myth“An operation on the nerve is needed to cure it.”What is true?
Fact
Surgery to relieve pressure on the facial nerve has not been shown to help most people. Medicines and care of the eye are the main treatment, and most people improve without an operation.
Questions to ask your doctor
Tick the ones you want answered and take them with you.
Common questions
Is Bell's palsy the same as a stroke?
No. In Bell's palsy the facial nerve is inflamed and only the face is affected. A stroke comes from a problem with the blood supply to the brain and can also cause a weak arm or leg, or slurred speech. Because the face can droop in both, a sudden droop should be checked by a doctor straight away.
Will my face go back to normal?
Most people recover fully, usually within a few weeks to 6 months, and many begin to improve within about two weeks. Some are left with some weakness, taste changes or twitching. Getting treatment early helps.
Can it happen again?
It usually happens only once. Rarely it comes back, sometimes years later. Tell your doctor if you notice the same weakness again.
How do I look after my eye?
If the eye does not close fully, it can dry out and become damaged. A doctor may advise lubricating eye drops and an ointment, and sometimes tape or a patch to keep the eye closed while you sleep. Tell the doctor at once if the eye becomes sore.