PassFinals
Neurology

Bell's palsy

Bell's palsy is an acute idiopathic unilateral peripheral facial-nerve palsy; forehead involvement and isolated lower-motor-neurone weakness support the diagnosis, but eye protection and exclusion of stroke, Ramsay Hunt syndrome and other causes are essential.

In a nutshell

Bell's palsy is an acute isolated peripheral facial palsy involving the forehead, eye and mouth. Exclude stroke and secondary causes, start high-dose oral corticosteroid treatment within 72 hours when appropriate, protect the cornea, and refer urgently for atypical features or a threatened eye.

Classic presentation

A patient with rapid unilateral facial weakness affecting forehead wrinkling, eye closure and the mouth, perhaps with altered taste or postauricular pain, but no limb or other cranial-nerve signs.

Key points

  • Forehead involvement supports a peripheral facial palsy, but the full neurological examination is essential because brainstem lesions can mimic it.
  • Bell's palsy is clinical; do not routinely image an uncomplicated isolated episode.
  • Offer high-dose oral corticosteroids within 72 hours using current BNF or local NHS protocol.
  • Incomplete eye closure needs lubricants and night-time protection; a painful, red or exposed cornea needs urgent ophthalmology.
  • Vesicles or severe ear symptoms suggest Ramsay Hunt syndrome or another ear cause, not uncomplicated Bell's palsy.
  • Bilateral, recurrent, gradual, progressive or non-recovering weakness needs targeted investigation and specialist referral.
  • NICE does not recommend routine specialist referral for an uncomplicated isolated adult Bell's palsy.

First-line investigation

Focused neurological, ear, skin, parotid and eye examination; targeted tests only when the history or examination is atypical.

Management

Exclude stroke and protect the eye

  • Use the acute neurological pathway for additional focal signs, and provide eye protection immediately when eyelid closure is incomplete.1,4,5

Confirm an isolated peripheral facial palsy

  • Examine the whole neurological system, ear, skin, parotid, mouth and cornea before calling the episode Bell's palsy.2,3

Start early corticosteroid treatment

  • Offer high-dose oral corticosteroid treatment within 72 hours when clinically appropriate, checking current BNF or local protocol for prescribing and contraindications.1,2,6

Protect function and comfort

  • Use lubricants and night-time eyelid protection, and provide practical advice for eating, drinking, speech, oral hygiene and emotional impact.1,4

Treat secondary causes and refer atypical disease

  • Identify Ramsay Hunt, Lyme disease, ear or parotid pathology, bilateral or recurrent palsy, additional cranial signs, gradual progression and threatened corneal disease.2,3,5

Review recovery and synkinesis

  • Safety-net recovery, refer absent or incomplete recovery and assess aberrant reinnervation or persistent functional impact through a facial-nerve service.1,5

Exam traps

  • Do not use forehead sparing as the only stroke discriminator; other neurological signs and brainstem disease matter.
  • Do not delay eye protection while waiting for a specialist appointment.
  • Antivirals are not routine monotherapy for Bell's palsy; vesicles point to Ramsay Hunt syndrome.
  • A normal initial Lyme test may not exclude infection when exposure or clinical features are persuasive.
  • Persistent weakness, recurrence, bilateral palsy, mass, ear disease or other cranial signs is not uncomplicated Bell's palsy.

Illustrations

Whole-side facial weakness in Bell's palsyClinical photograph showing unilateral peripheral facial weakness affecting the forehead, eye closure and mouth. Include consent or open-licence information and avoid presenting one severity grade as universal.James Heilman, MD, Wikimedia Commons · CC-BY-SA-3.0

Key sources

  1. NICE NG127, Suspected neurological conditions: recognition and referral (Updated 2 October 2023; Bell's palsy recommendations cover isolated peripheral facial palsy, no routine referral, early steroid treatment and eye protection)Updated 2 Oct 2023
  2. NHS Highland, Bell's Palsy guideline (Adult emergency and primary-care guideline, version 3, last reviewed 27 February 2025; includes assessment, Lyme-risk questions, eye care, early corticosteroids and referral criteria)Updated 27 Feb 2025
  3. NHS Greater Glasgow and Clyde, facial palsy referral guidance (NHS ENT referral pathway reviewed May 2025; covers stroke pattern, ear and parotid examination, eye protection and referral triggers)Updated 7 May 2025
  4. University Hospital Southampton, facial-nerve palsy patient information (NHS patient information covering steroid treatment, lubricants, ointment, eyelid taping and rehabilitation)
  5. University Hospital Southampton, Wessex Facial Nerve Centre referral guidance (NHS referral guidance for eye risk, atypical or progressive palsy, non-recovery, synkinesis and functional impact)
  6. BNF, current prescribing information for Bell's palsy medicines (Current UK prescribing source for prednisolone, aciclovir, valaciclovir and ocular lubricants; direct access was restricted and the browser session was unavailable, so unsupported doses were omitted)

This page is exam revision material, not medical advice, and must not be used for patient care. Always check drug doses against the BNF and current guidance. Full disclaimer.