Causes and Risk Factors
The facial nerve travels through a narrow bony canal on its way to the face; when it becomes inflamed and swollen, its signals are blocked:- Viral reactivation: Bell's palsy is believed to be triggered most often by reactivation of common viruses, particularly the herpes simplex virus that causes cold sores.
- Diabetes: People with diabetes have a higher risk of Bell's palsy.
- Pregnancy: Risk rises in the third trimester and just after delivery.
- Recent illness: An upper respiratory infection often precedes the facial weakness.
Symptoms
Symptoms develop rapidly, usually over hours to three days, and involve one side of the face:- Facial drooping: A flattened smile, sagging eyebrow, and inability to fully close the eye on the affected side — including the forehead, which is an important clue.
- Eating and speaking changes: Drooling, food catching in the cheek, or slightly slurred words from weak facial muscles.
- Eye symptoms: Dryness or excessive tearing because blinking is impaired.
- Altered taste: Reduced or changed taste on the front of the tongue.
- Ear discomfort: Pain around the jaw or behind the ear, and unusual sensitivity to sound on that side.
When to Seek Immediate Care
Sudden facial drooping should be treated as an emergency until stroke is excluded. Call 911 right away if facial weakness comes with arm or leg weakness, numbness, trouble speaking or understanding, vision loss, severe headache, or dizziness. A stroke typically spares the forehead muscles, but this distinction is for clinicians to make — never try to diagnose yourself at home.Diagnosis
Bell's palsy is diagnosed by examination after other causes are excluded. Your physician will confirm that the weakness involves the whole side of the face, look for rashes or blisters that suggest shingles of the ear, consider Lyme disease when exposure is possible, and check blood sugar. Imaging or nerve testing is reserved for atypical cases — weakness that comes on slowly, affects both sides, or fails to improve as expected.Treatment
Early treatment improves the odds of full recovery:- Corticosteroids: A course of prednisone, ideally started within 72 hours of onset, reduces nerve swelling and clearly improves recovery.
- Antiviral medication: Valacyclovir is sometimes added to steroids, particularly in severe cases.
- Eye protection: Because the eyelid cannot close fully, lubricating drops during the day, ointment at night, and taping or a patch during sleep protect the cornea — this is essential to prevent lasting eye damage.
- Facial exercises and time: Gentle facial movement practice supports recovery as nerve function returns over weeks to months.
Complications
Most people recover completely within a few weeks to a few months, but a minority are left with lasting effects:- Incomplete recovery: Some facial weakness can persist, most often when the initial paralysis was complete and improvement was slow to begin.
- Corneal injury: An eye that cannot close fully may dry out, become scratched, or develop an infection — the reason eye protection is emphasized from the first day.
- Synkinesis: As nerve fibers regrow they can reach the wrong muscles, so the eye may narrow when you smile or the corner of the mouth may twitch when you blink.
- Tearing while eating: Misdirected regrowth can also send signals to the tear gland, causing the eye to water during meals.
Recovering From Bell's Palsy Week by Week
Two things decide how Bell's palsy turns out: starting steroids quickly and protecting an eye that cannot close. Almost everything else is time. Here is what those weeks look like.
The 72-hour window
A course of prednisone started within about three days of the first weakness measurably improves the chance of complete recovery, which is why this deserves a same-day visit, not a wait-and-see week. The course runs roughly ten days, taken in the morning to limit sleeplessness; irritability, appetite, fluid retention, and a temporary rise in blood sugar are expected, and anyone with diabetes should check readings more often. Valacyclovir is often added when the paralysis is complete or severe; the benefit is modest but it does not replace the steroid.
Eye protection is the part people skip
An eye that cannot blink dries out within hours, and a scratched or ulcerated cornea is the one permanent injury Bell's palsy commonly causes. Use preservative-free artificial tears as often as hourly while awake, a thick ointment at bedtime, and tape the lid closed or wear a moisture-chamber shield overnight. Wraparound sunglasses help outdoors, vents and fans should point away, and contact lenses come out until blinking returns. Redness, pain, or blurred vision needs same-day eye care. Our dry eye syndrome page and dry eye and air conditioning article cover the products.
What the timeline actually looks like
Most people notice the first flicker of movement within two to three weeks and keep improving over one to three months. Recovery is slower and less complete when the paralysis was total at the start, and can take six months or more. Eating takes practice: small bites, chewing on the strong side, a straw for drinks, and checking the weak cheek for food. If there is no movement by three to four months, or weakness still worsens after two weeks, the diagnosis is revisited with imaging or nerve testing.
Facial retraining, done gently
Small, slow, mirror-guided movements and light massage from a facial therapist support recovery. Forceful grimacing, gum chewing, and electrical stimulation are discouraged, because regrowing nerve fibers can wire into the wrong muscles and produce synkinesis: the eye narrowing with a smile, the mouth twitching with a blink. Established synkinesis is treated with botulinum toxin injections and retraining, not more effort.
When it is not Bell's palsy
Weakness that spares the forehead, or comes with arm or leg weakness, numbness, or trouble speaking, is a stroke or TIA until proven otherwise: call 911. Severe ear pain with blisters in the ear canal, hearing loss, or vertigo suggests Ramsay Hunt syndrome from shingles, which needs higher antiviral doses fast. Weakness on both sides, weakness creeping in over weeks, a known tick bite, or a third episode all point away from Bell's palsy; our tick-borne illness guide covers local exposures and our sudden facial drooping article the first hours. Our neurologic team manages treatment and follow-up. NINDS and MedlinePlus publish patient guidance on Bell's palsy.
If one side of your face has just weakened, schedule a visit today; the steroid works best within three days.