Bell’s palsy is a sudden weakness or paralysis of the muscles on one side of your face, caused by inflammation of the facial nerve. It’s the most common form of facial paralysis, and it typically reaches peak severity within 24 to 72 hours of the first symptom. Though alarming when it happens, most people recover completely, and early treatment with steroids significantly improves outcomes.
What Happens to the Facial Nerve
Your facial nerve (the seventh cranial nerve) controls the muscles responsible for blinking, smiling, frowning, and raising your eyebrows. It also carries signals for taste on the front two-thirds of your tongue and helps regulate tear and saliva production. In Bell’s palsy, this nerve becomes inflamed and swollen inside a narrow bony canal in the skull, which compresses it and disrupts the signals it sends to your facial muscles.
About a third of cases are linked to herpes simplex virus type 1 (the same virus behind cold sores). The virus can damage the protective coating around the nerve fibers, a process called demyelination, which impairs the nerve’s ability to transmit signals. Other viruses associated with the condition include varicella-zoster (chickenpox/shingles), Epstein-Barr, and cytomegalovirus. In many cases, though, no specific cause is identified.
Symptoms and How They Develop
The hallmark of Bell’s palsy is one-sided facial weakness that progresses over hours to days. You might first notice difficulty smiling, a drooping corner of your mouth, or trouble closing one eye. These symptoms can range from mild weakness to complete paralysis on the affected side.
Beyond the obvious facial drooping, several other symptoms are common:
- Sounds seem louder on the affected side because a tiny muscle in the ear (the stapedius) stops dampening vibrations
- A metallic taste or numbness on the same side of the tongue
- Eye dryness or excessive tearing, because the eye can’t close properly and the normal tear-pumping mechanism fails
- Nasal congestion on the affected side from weakened nostril muscles
- Difficulty eating and speaking, since the muscles around the mouth lose tone
- Pain near the ear or jaw on the affected side
How to Tell It Apart From a Stroke
This is the question most people have in the moment, and it matters. The key difference is the forehead. In Bell’s palsy, the entire half of the face is affected, including the forehead. You won’t be able to raise your eyebrow on the weak side. In a stroke, the forehead is typically spared because it receives nerve signals from both sides of the brain, so you can still wrinkle your forehead even though the lower face droops.
Other distinguishing features: Bell’s palsy develops progressively over hours or days, while stroke symptoms hit suddenly, within seconds. Stroke also tends to involve other symptoms like arm or leg weakness, slurred speech, vision changes, or confusion. Bell’s palsy does not. If you’re experiencing any limb weakness, speech difficulty, or sudden vision problems alongside facial drooping, that pattern points toward stroke and warrants emergency care.
Who Is at Higher Risk
Bell’s palsy can happen to anyone, but certain groups face elevated risk. Pregnant women are about three times more likely to develop it than the general population, with most cases occurring in the third trimester. People with diabetes, Lyme disease, myasthenia gravis, and multiple sclerosis also have higher rates. Upper respiratory infections sometimes precede an episode, likely because of the viral connection.
Treatment That Makes a Difference
The single most important treatment is a course of corticosteroids started within 72 hours of symptom onset. A standard regimen is a 10-day course (equivalent to about 60 mg of prednisone daily), which significantly improves the chances of complete recovery. The steroid reduces inflammation around the nerve, relieving the compression inside that narrow bony canal. If more than three days have passed before you start treatment, steroids may still help, but the benefit is less well established.
Antiviral medications are sometimes prescribed alongside steroids, given the viral connection. However, the evidence for adding them is weak. The American Academy of Neurology notes that antivirals combined with steroids do not increase the probability of recovery by more than 7% compared to steroids alone, and a clear benefit has not been established. Your doctor may still offer them, particularly in severe cases, but they are not considered essential.
Protecting Your Eye
If you can’t fully close your eye on the affected side, protecting it from drying out and corneal damage is critical. Lubricating eye drops during the day and thicker ointment at night help keep the surface moist. Some people tape the eye shut while sleeping. This isn’t a minor detail. Corneal injury from exposure is one of the most preventable complications of Bell’s palsy, and consistent eye care should start immediately.
Recovery Timeline and Outlook
Most people begin to see the first signs of improvement around 48 days after onset, though this varies widely. Some notice movement returning within a few weeks, while others wait several months. In one study tracking patients over 12 months, about 64% achieved complete recovery. The remaining 36% had some degree of lingering weakness or other complications, though many in this group still experienced significant improvement short of full recovery.
Severity at the outset matters. Doctors often use a six-point grading scale to assess how much function remains. At the mild end, you might have slight asymmetry but can still close your eye with gentle effort. At the severe end, there’s no movement at all and visible drooping of the brow and mouth even at rest. People with milder initial presentations tend to recover more fully and more quickly.
Complications After Recovery
When the facial nerve regenerates after significant damage, the new nerve fibers don’t always find their way back to the correct muscles. This misdirected regrowth causes a condition called synkinesis, where moving one part of your face triggers involuntary movement in another. For example, you might find that smiling causes your eye to close, or that chewing makes your cheek twitch. This happens because a single regenerating nerve fiber branches out and connects to two different muscles instead of one.
A rarer complication is “crocodile tears,” where eating triggers tearing from the eye on the affected side. This occurs when nerve fibers meant for salivary glands accidentally regrow toward the tear gland instead. Both synkinesis and crocodile tears can be managed with targeted therapies, including physical therapy exercises and, in some cases, small injections to relax the overactive muscles.
How Severity Is Graded
If you’ve been diagnosed, you may hear your doctor reference a grade from I to VI. Grade I means normal, symmetric function. Grade II is mild dysfunction with slight asymmetry but full eye closure. Grade III involves noticeable asymmetry and the ability to close the eye only with full effort. Grade IV means incomplete eye closure and moderate asymmetry when trying to move. Grade V shows severe asymmetry with barely perceptible movement, and Grade VI is complete paralysis with no movement at all. This grading helps track your recovery over time and guides decisions about treatment intensity.