What is the preferred antiviral (antiviral medication) for the treatment of Bell's palsy?

Valacyclovir is the Preferred Antiviral for Bell's Palsy When Combined with Steroids

For Bell's palsy, valacyclovir is the preferred antiviral when antiviral therapy is used in combination with steroids, showing superior recovery rates compared to other antivirals or placebo plus steroids.

Antiviral Therapy in Bell's Palsy

Key Recommendations

• Antiviral monotherapy should NOT be used for Bell's palsy 1
• Oral steroids are the primary treatment for Bell's palsy 1
• Combination therapy with an antiviral plus steroids may offer a small additional benefit 1
• When an antiviral is used, valacyclovir shows the strongest evidence for efficacy 2

Evidence-Based Treatment Algorithm

1. First-line treatment: Oral steroids (prednisolone) within 72 hours of symptom onset

   • Prednisolone 50mg daily for 10 days OR
   • Prednisolone 60mg daily for 5 days followed by 5-day taper 1

2. Consider adding antiviral therapy:

   • Valacyclovir 1000mg three times daily for 7 days is the preferred antiviral 2
   • Must be initiated within 72 hours of symptom onset 1
   • Particularly beneficial in cases of complete or severe facial palsy 2

3. Avoid antiviral monotherapy:

   • Strong evidence shows antivirals alone are no better than placebo 1

Comparative Evidence for Antivirals

Valacyclovir vs. Other Options

Valacyclovir has demonstrated superior efficacy when combined with steroids:

• Recovery rate of 96.5% with valacyclovir plus prednisolone vs. 89.7% with placebo plus prednisolone 2
• Particularly effective in severe cases: 95.7% recovery with valacyclovir plus prednisolone vs. 86.6% with placebo plus prednisolone 2

While a large multicenter trial by Engström et al. found no benefit of valacyclovir 3, a more targeted study by Hato et al. that excluded zoster sine herpete cases showed significant benefit 2. This suggests valacyclovir may be particularly effective when used in appropriate cases.

Clinical Considerations

• Timing is critical: Treatment should be initiated within 72 hours of symptom onset 1
• Patient selection: Consider combination therapy especially for:
  • Severe or complete facial paralysis 2
  • Older patients (>60 years) who may benefit more from combination therapy 4
• Duration of treatment: 7 days of valacyclovir appears optimal 2

Common Pitfalls to Avoid

1. Using antiviral monotherapy: Strong evidence shows this is ineffective 1
2. Delaying treatment: Benefits diminish significantly after 72 hours 1
3. Neglecting eye protection: Patients with incomplete eye closure need protective measures regardless of medication choice 1
4. Overlooking patient factors: Elderly patients may benefit more from combination therapy 4
5. Failing to distinguish Bell's palsy from other causes: Ensure proper diagnosis before initiating treatment 1

Special Populations

• Children: Limited evidence for antiviral use; steroids may be considered with caregiver involvement in decision-making 1
• Elderly patients: May benefit more from combination therapy; one study showed 100% recovery in patients >60 years with combination therapy vs. 42% with no treatment 4
• Pregnant women: Treatment should be individualized based on risk-benefit assessment 1

While the overall evidence for adding antivirals to steroids is mixed, when an antiviral is indicated, valacyclovir has the strongest evidence for efficacy, particularly in severe cases of Bell's palsy.