What is the recommended dose of acyclovir (antiviral medication) for a patient presenting with Bell's palsy within 72 hours?

Acyclovir Dosing for Bell's Palsy

Yes, acyclovir 400 mg five times daily for 10 days is the correct dose when used in combination with corticosteroids for Bell's palsy within 72 hours of symptom onset, though acyclovir should never be prescribed alone as it is ineffective as monotherapy. 1, 2

Primary Treatment: Corticosteroids Are Essential

• Oral corticosteroids are the only proven effective treatment for Bell's palsy and must be prescribed within 72 hours of symptom onset for patients 16 years and older. 1, 2
• The recommended regimen is prednisolone 50 mg daily for 10 days OR prednisone 60 mg daily for 5 days followed by a 5-day taper. 1, 2
• Evidence demonstrates 83% recovery at 3 months with prednisolone versus 63.6% with placebo, and 94.4% recovery at 9 months versus 81.6% with placebo. 1, 3

Acyclovir: Only as Combination Therapy

• Acyclovir should NEVER be prescribed as monotherapy for Bell's palsy—it is completely ineffective alone. 1, 2
• Acyclovir may be offered in combination with corticosteroids within 72 hours of symptom onset as an optional add-on therapy, though the added benefit is minimal. 1, 2
• The correct acyclovir dosing when used in combination is 400 mg orally five times daily for 10 days (due to its lower oral bioavailability requiring more frequent dosing compared to valacyclovir). 2

Evidence Supporting Combination Therapy

• The landmark 2007 trial showed no benefit of acyclovir alone (71.2% recovery versus 75.7% without acyclovir, P=0.50), but combination therapy with prednisolone plus acyclovir achieved 79.7% recovery at 3 months and 92.7% at 9 months. 3
• Guidelines classify combination therapy as an "option" rather than a strong recommendation, acknowledging that while the benefit is small, the risks are minimal. 2

Critical Treatment Algorithm

Within 72 hours of symptom onset:

• First-line: Prescribe oral corticosteroids (prednisolone 50 mg daily for 10 days OR prednisone 60 mg daily for 5 days with 5-day taper). 1, 2
• Optional add-on: May add acyclovir 400 mg five times daily for 10 days in combination with corticosteroids. 2
• Never: Prescribe acyclovir alone—this is ineffective and delays appropriate treatment. 1, 2

Beyond 72 hours:

• Do not initiate corticosteroids or antivirals, as there is no evidence of benefit after this window. 1, 4

Mandatory Eye Protection

• Implement aggressive eye protection immediately for all patients with impaired eye closure to prevent corneal damage. 1, 2
• Use lubricating ophthalmic drops every 1-2 hours while awake, ophthalmic ointment at bedtime, eye patching or taping at night (with careful instruction to avoid corneal abrasion), and sunglasses outdoors. 1, 2

Common Pitfalls to Avoid

• Prescribing acyclovir alone is the most critical error—it provides no benefit and delays effective corticosteroid treatment. 1, 2
• Delaying treatment beyond 72 hours significantly reduces the effectiveness of corticosteroid therapy. 1, 5
• Inadequate eye protection can lead to permanent corneal damage, particularly in patients with complete inability to close the eye. 1, 2
• Failing to reassess or refer patients with incomplete recovery at 3 months delays access to reconstructive options. 1, 2