One-Sided Facial Weakness: Bell’s Palsy or Stroke?

Short answer: New one-sided facial drooping or weakness should not be labeled Bell’s palsy at home. Obtain prompt medical assessment so stroke can be excluded. Call emergency services now if facial droop comes with arm or leg weakness, abnormal speech or understanding, vision change, severe dizziness or loss of balance, a sudden severe headache, confusion or reduced consciousness. Record when the person was last known well. Even when the whole side of the face is weak—including the forehead and eye closure—and no other symptom is obvious, same-day assessment matters because Bell’s palsy is a clinical diagnosis, treatment works best when started early, and an eye that will not close needs protection.

Who this answer is for

This covers a first episode of new facial drooping, asymmetry, reduced movement at the corner of the mouth, difficulty closing one eye or loss of forehead movement in an adult. Long-standing asymmetry, facial twitching, a change immediately after surgery or cosmetic injection, and facial-bone trauma may follow different pathways. Pregnancy, childhood and substantial immune suppression also require individualized assessment.

How Bell’s palsy and stroke may look different

Central facial weakness from a problem in the brain, including stroke, often affects the lower face while forehead wrinkling and eye closure are relatively preserved. Peripheral facial weakness, including Bell’s palsy, can weaken the forehead, eye and mouth on the same side. Altered taste, increased sensitivity to sound or pain behind the ear can accompany Bell’s palsy.

Forehead movement is a clinical clue, not a reliable home rule-out test. Korea’s KDCA describes this pattern while also advising that new facial weakness be examined to determine whether a brain disorder is responsible. Do not downgrade the urgency or skip assessment based on the face alone.

Stroke warning signs: call emergency services now

Do not wait if facial change occurs suddenly with any of the following:

  • weakness or numbness in one arm or leg, or one arm drifting downward
  • slurred, strange or absent speech, or difficulty understanding language
  • sudden blurred, double or lost vision
  • difficulty walking, severe dizziness, or loss of balance or coordination
  • a sudden severe headache without a known cause
  • confusion, seizure, reduced consciousness or rapidly worsening symptoms

Symptoms that resolve after a few minutes can still be a transient ischemic attack and require emergency assessment. Do not force food, drink or pills, and do not drive yourself. Record the last-known-well time and the time the change was first noticed.

If it is only the face, can you assume Bell’s palsy?

No. Bell’s palsy is the most common peripheral facial palsy, but it is diagnosed after other causes are considered. Ear pain or blisters with hearing loss, tinnitus or vertigo can suggest Ramsay Hunt syndrome. Middle-ear infection, trauma, tumors and inflammatory or autoimmune disorders can also affect the facial nerve.

Bell’s palsy often evolves over hours to a few days and reaches its worst point within about 72 hours. The NHS and KDCA emphasize early assessment, and steroid treatment is most useful when started early. Do not self-start leftover steroids or antiviral medicines; pregnancy, diabetes, infection risk and alternative diagnoses affect prescribing.

Why an eye that will not close needs attention

Incomplete eyelid closure can dry and injure the cornea. Same-day assessment should check eyelid closure and the eye surface and determine whether lubricating drops, ointment or nighttime eyelid protection is needed. Avoid contact lenses. Eye pain, marked redness, light sensitivity or reduced vision requires urgent eye assessment.

Do not press the eye shut forcefully or place ordinary skin tape over the eye surface. The appropriate protection method depends on how well the eyelid closes and the condition of the skin and cornea.

What clinicians may check

The examination includes forehead, eye and mouth movement as well as limb strength and sensation, speech, vision and balance. Clinicians may inspect the ear and mouth for blisters or infection and ask about hearing change, trauma, surgery, medical conditions and medicines. Typical Bell’s palsy does not require MRI in every person, but slow progression, recurrence or another neurological finding may require imaging or further tests.

Applying Korean and overseas pathways

In South Korea, use 119 for stroke warning signs. Even if the weakness appears limited to the face, seek same-day neurological or emergency assessment; ear pain, blisters or hearing change may also prompt ENT evaluation. In the United States use 911, and in the UK use 999 for suspected stroke. NHS 111 is a UK service. Follow the emergency number and clinical pathway where you are.

What to record and ask

Record the last time the face was normal, when the change was first noticed, whether onset was sudden or progressed over hours, and changes in forehead wrinkling, eye closure and smiling. Note any arm or leg, speech, vision or balance symptom. Also report ear pain or blisters, taste change, hearing loss, tinnitus, vertigo, recent infection, trauma or surgery, pregnancy, diabetes and current medicines.

  • What examination or testing is needed to exclude stroke or another central cause?
  • If this is Bell’s palsy or another peripheral palsy, when should treatment begin?
  • How should I protect the eye during the day and overnight?
  • Which new symptoms require an immediate return to emergency care?

Related reading

Sources

Reviewed: October 24, 2026. General health information, not an individual emergency assessment, diagnosis, imaging decision or prescription. No clinician-review claim is made.