Face muscles weak on one side: what to know

Facial weakness may involve the forehead, eyelid, cheek, or mouth. It can affect smiling, closing one eye, speaking, chewing, or taste. Causes include problems affecting the facial nerve, brain, or nearby structures; muscle weakness elsewhere may point to a broader issue. Cervical radiculopathy usually affects nerves from the neck into the arm rather than causing isolated facial weakness, so the distribution matters. A clinician will ask when it began and examine strength, sensation, eye closure, and coordination.

If the change is new, note the exact time you were last normal and seek medical advice promptly. Do not drive yourself if symptoms are sudden or worsening. If one eye cannot close fully, protect it from drying with clinician-guided eye care and avoid contact lenses until assessed. Do not begin vitamin D supplementation or strength training rehabilitation for this symptom without identifying its cause; treatment depends on the examination.

Call emergency services immediately for sudden facial weakness with trouble speaking, confusion, severe headache, dizziness, loss of balance, or weakness or numbness in an arm or leg. Urgent assessment is also needed for new inability to close an eye, severe eye pain, swallowing difficulty, or rapidly worsening symptoms. Even when the face is the only affected area, prompt evaluation helps distinguish nerve conditions from emergencies.

Ask which part of the face is weak, whether you need brain or nerve tests, and how to protect the eye. Ask whether medicines, vitamin levels, infection, or another neurological problem could contribute and when rehabilitation would be safe.