Is Botox (botulinum toxin) effective for treating Bell's palsy?

Botox for Bell's Palsy: Limited Role in Acute Treatment, Valuable for Chronic Sequelae

Botox is NOT recommended for treating acute Bell's palsy itself, but it is highly effective for managing chronic complications like synkinesis, hyperkinesis, and facial asymmetry that develop after incomplete recovery. 1, 2

Acute Bell's Palsy: No Role for Botox

The American Academy of Otolaryngology-Head and Neck Surgery clinical practice guidelines do not recommend botulinum toxin for acute Bell's palsy treatment. 1, 2 The evidence-based acute management focuses on:

• Oral corticosteroids within 72 hours (prednisolone 50 mg daily for 10 days OR prednisone 60 mg daily for 5 days with 5-day taper) for patients ≥16 years old 2
• Eye protection measures for patients with impaired eyelid closure (lubricating drops, ointments, moisture chambers, eye taping/patching) 1, 2
• Optional combination antiviral therapy with steroids within 72 hours 2

Botox has no established role in promoting nerve recovery during the acute phase. 1

Chronic Sequelae: Where Botox Excels

Synkinesis and Hyperkinesis

Botox is highly effective for treating facial synkinesis (involuntary facial movements) and hyperkinesis (excessive muscle activity) that commonly develop after incomplete recovery from Bell's palsy. 3

• A prospective study of 41 patients with post-facial palsy synkinesis/hyperkinesis (28 from Bell's palsy) showed statistically significant improvement in both objective and subjective measures after botulinum toxin A treatment 3
• All patients demonstrated some improvement, with positive correlation between objective Sunnybrook Grading Scale scores and patient-reported outcomes 3
• Treatment is safe, minimally invasive, and can be repeated as needed 3

Facial Asymmetry

For patients with persistent facial asymmetry after Bell's palsy, contralateral Botox injections (injecting the non-paralyzed side) effectively improve facial symmetry at rest and during movement. 4, 5

• In 18 patients with acute facial palsy who couldn't receive optimal medical/surgical treatment, contralateral botulinum toxin A (mean dose 47.5 U, range 32-68 U) produced marked relief of facial asymmetry in 8 patients within 1 month 4
• The technique reduces relative hyperkinesis on the healthy side, creating greater symmetric function 4
• For "late recovered" Bell's palsy with muscle tightness, deepened nasolabial fold, and blepharospasm, four monthly Botox injections improved patient self-assessment of facial symmetry, ability to go out in public, and self-worth 5

Eye Protection in Chronic Cases

Botox injections can improve eyelid closure for several months in patients with persistent lagophthalmos (incomplete eyelid closure), serving as a bridge or alternative to surgical options. 1, 2

• This application addresses ongoing risk of corneal complications (exposure keratitis, corneal ulceration) in patients with incomplete recovery 1
• Surgical options (eyelid weights, tarsorrhaphy) provide permanent improvement, while Botox offers temporary relief 1, 2

Clinical Algorithm for Botox Use in Bell's Palsy

Acute Phase (0-3 months):

• Do NOT use Botox 1, 2
• Prescribe oral corticosteroids within 72 hours 2
• Implement eye protection measures 2

Subacute/Chronic Phase (>3 months):

• Reassess or refer to facial nerve specialist if incomplete recovery at 3 months 2
• Consider Botox for:
  • Synkinesis/hyperkinesis: Inject affected muscles on paralyzed side 3
  • Facial asymmetry: Inject contralateral (healthy) side to balance hyperkinesis 4, 5
  • Persistent lagophthalmos: Inject to improve eyelid closure 1, 2

Treatment Approach:

• Use 2.5-3 U per injection site, total dose 32-68 U depending on extent of involvement 4
• Expect improvement within 1 month, with effects lasting 3-6 months 1, 4
• Repeat injections as needed for sustained benefit 3, 5

Important Caveats

The benefit of Botox is most apparent during facial animation rather than at rest, which may not be fully captured by static measurements but is highly valued by patients. 5

Botox does not cure the underlying nerve dysfunction—it manages symptoms by temporarily paralyzing overactive muscles or balancing asymmetry. 1

Recent evidence suggests antivirals may reduce synkinesis risk, potentially decreasing the future need for Botox in some patients. 6