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Bell's Palsy: Sudden Facial Weakness and the 72-Hour Window

Bell's palsy weakens one side of the face, forehead included — the detail that separates it from a stroke. Steroids started within 72 hours markedly improve recovery, and protecting an eye that won't close matters just as much.

Updated 2026-09-056 min read2 cited sourcesEducational — not medical advice

The facial nerve swells inside a narrow bony canal, and the pressure blocks the signal to one side of the face

In short

Bell's palsy weakens one side of the face, forehead included — the detail that separates it from a stroke. Steroids started within 72 hours markedly improve recovery, and protecting an eye that won't close matters just as much.

Emergency if: Any sudden facial droop — call emergency services so a stroke can be excluded, especially with arm weakness, slurred speech or confusion.

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01

Treat a New Facial Droop as an Emergency First

A face that suddenly droops on one side can be a stroke, and a stroke is time-critical. Nobody should diagnose themselves with Bell's palsy at home. Call emergency services, especially if there is also arm weakness, difficulty speaking or understanding, or numbness.

There is a distinguishing sign, and clinicians use it within minutes: Bell's palsy weakens the whole side of the face including the forehead, so the eyebrow will not lift and the eye will not close. A stroke usually spares the forehead, because that muscle receives signals from both sides of the brain.

02

What Bell's Palsy Is

The facial nerve runs from the brainstem to the face through a narrow bony channel. If it becomes inflamed and swells, there is nowhere for it to expand, so the nerve is compressed and stops conducting properly. The result is weakness or complete paralysis on that side.

The trigger is not fully settled; reactivation of a common cold-sore virus is the leading explanation, and many people report a viral illness beforehand. Risk is higher in pregnancy — particularly the third trimester and the weeks after delivery — and in people with diabetes, obesity or high blood pressure.

03

How It Presents

It comes on over hours, typically reaching its worst within about three days. The mouth corner droops, drinks escape from that side, the eye waters or feels dry, and blinking on that side stops working properly.

Less expected features are common and can be alarming if you do not know about them: pain behind or below the ear, altered or dulled taste, and sounds seeming uncomfortably loud in that ear. Hearing itself is not affected.

04

Treatment: Steroids Early, Eye Care Throughout

A short course of oral corticosteroids started within 72 hours of the first symptom meaningfully improves the chance of full recovery. That deadline is the reason to be seen promptly rather than waiting to see whether it settles. Antiviral tablets on their own are not effective, though they are sometimes added to steroids in severe cases.

If the eye will not close, it is at real risk of drying out and scarring the cornea. Lubricating drops through the day, ointment at night, taping or padding the eye closed for sleep, and sunglasses outdoors are not optional extras — they protect the sight on that side while the nerve recovers.

05

Recovery, and When It Is Something Else

Most people notice the first improvement within two to three weeks, and symptoms should largely settle within about six months — though it takes longer for some. The outlook is best for those who keep some movement from the start and who were treated early. A minority are left with lasting weakness, tightness or involuntary movement, and should be referred rather than left to adjust.

Some presentations are not Bell's palsy at all: a painful rash or blisters in or around the ear suggests shingles of the facial nerve, which needs antiviral treatment; weakness on both sides, a gradual onset over weeks, or other neurological signs all point elsewhere and need investigation.

When to act

Emergency — act now

Any sudden facial droop — call emergency services so a stroke can be excluded, especially with arm weakness, slurred speech or confusion.

Same-day — call promptly

Facial weakness already assessed as Bell's palsy but not yet treated, or a painful rash or blisters near the ear — steroids and antivirals work best when started within 72 hours.

Routine — see a doctor

An eye that still will not close fully, or weakness that has not improved after three months — ask for an eye review and a specialist referral.

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