What is Bell palsy?
Bell palsy is sudden weakness on one side of your face. It happens when a nerve in your face (called the facial nerve) swells and gets squeezed.
Bell palsy affects only one side of your face
That side of your face becomes weak and droops
Treatment usually involves medicine called corticosteroids
Most people with Bell palsy get better within several months, even without treatment
What causes Bell palsy?
Doctors don’t always know what causes Bell palsy. An infection may cause the nerve to swell. In some cases, it’s caused by a virus like those that cause shingles, cold sores, mono, or the flu.
What are the symptoms of Bell palsy?
Symptoms start suddenly, usually within hours. Within 48 to 72 hours, your symptoms are as bad as they’ll get.
Bell palsy weakens the muscles on one side of your face. Sometimes you have a little pain behind your ear before the weakness starts. The weakness may range from mild weakness to a total inability to move, called paralysis. On your weak side, you may have:
A hard time making an expression, such as wrinkling your forehead, blinking, or smiling
Numbness or a heavy feeling
Trouble closing your eye, causing it to become dry
Dry mouth or drooling
Trouble tasting with the front part of your tongue
Hearing that makes sounds seem louder than usual
Your facial nerve may not always heal the right way. This can cause unusual face movements or watery eyes. Sometimes, your facial muscles may stay tight.
How can doctors tell if I have Bell palsy?
If you start noticing signs of Bell palsy, see a doctor as soon as possible. Some other conditions, such as a stroke Stroke A stroke is a sudden brain problem that happens when a blood vessel in your brain either gets blocked or breaks open and bleeds. Part of your brain stops getting blood. Brain tissue that doesn't... read more or Lyme disease Lyme Disease Lyme disease is a certain disease you get from being bitten by infected ticks. It's called Lyme disease because it was first discovered in Lyme, Connecticut. A type of tick called the deer tick... read more 
, are more serious than Bell palsy and can cause similar symptoms.
The doctor will examine you to diagnose Bell palsy. There's no specific test for Bell palsy. To confirm your symptoms aren't caused by something else, your doctor may do tests:
Blood tests
MRI Magnetic Resonance Imaging (MRI) MRI is a test that uses a machine with a powerful magnet to make pictures of the inside of your body. A computer records changes in the magnetic field around your body. The computer then uses... read more
or CT scans Computed Tomography A CT scan uses a large machine shaped like a large donut to take x-rays from many angles. A computer then takes the x-rays and creates many detailed pictures of the inside of your body. Each... read more 
of your brain
How do doctors treat Bell palsy?
Most people who have Bell palsy recover completely, without treatment, in several months
Some people who have severe Bell palsy and can't move one side of their face at all may not recover fully
If you’ve had symptoms for less than 48 hours, doctors may give you medicine called a corticosteroid that can make full recovery even more likely
If you cannot close your eye all the way, your doctor may give you eye drops or a patch to protect your eye from drying out too much
