What are the recommended doses of dexamethasone (Decadron) and acyclovir for treating an adult with acute Bell’s palsy?

Recommended Doses for Bell's Palsy Treatment

For adults with acute Bell's palsy, prescribe prednisolone 50 mg once daily for 10 days OR prednisone 60 mg once daily for 5 days followed by a 5-day taper, initiated within 72 hours of symptom onset; acyclovir should NOT be prescribed alone but may be added at 400 mg five times daily for 10 days as an optional adjunct to steroids, though the added benefit is minimal. 1

Corticosteroid Dosing (Primary Treatment)

Prednisolone is the preferred corticosteroid with two evidence-based regimens 1:

• Prednisolone 50 mg orally once daily for 10 days (no taper required) 1
• Prednisone 60 mg orally once daily for 5 days, then taper over 5 days 1

Critical timing requirement: Treatment must begin within 72 hours of symptom onset—initiating steroids after this window provides no proven benefit and should be avoided 1, 2

Evidence Supporting Steroid Efficacy

• 83% complete recovery at 3 months with prednisolone versus 63.6% with placebo (absolute benefit +19.4%; NNT = 6) 1, 3
• 94.4% complete recovery at 9 months with prednisolone versus 81.6% with placebo (absolute benefit +12.8%; NNT = 8) 1, 4

Steroid Potency Equivalencies

Understanding steroid potency ratios prevents underdosing 1:

• Prednisone is 4× more potent than hydrocortisone
• Methylprednisolone is 5× more potent than hydrocortisone
• Dexamethasone is 25× more potent than hydrocortisone

For dexamethasone conversion: The equivalent dose would be approximately 2.4 mg daily (60 mg prednisone ÷ 25 = 2.4 mg dexamethasone), though this is not the standard regimen studied in clinical trials 1

Weight-Based Dosing Considerations

• For patients significantly above or below average weight, consider 1 mg/kg/day prednisone (maximum 60 mg/day) 1
• In pediatric patients, use prednisolone 1 mg/kg/day (maximum 50-60 mg) for 5-10 days followed by a 5-day taper 5

Acyclovir Dosing (Optional Adjunct Only)

Acyclovir monotherapy is completely ineffective and should NEVER be prescribed alone 6, 1

When to Consider Adding Acyclovir

Acyclovir may be offered as an optional adjunct to steroids within 72 hours of onset, with the understanding that the added benefit is small 6, 1:

• Acyclovir 400 mg orally five times daily for 10 days 1
• Alternative: Valacyclovir 1000 mg orally three times daily for 7 days 1

Evidence for Combination Therapy

The benefit of adding antivirals to steroids is modest and inconsistent 6:

• One trial showed 96.5% recovery with combination therapy versus 89.7% with steroids alone (absolute benefit +6.8%) 6
• However, the largest high-quality trials (BELLS study with 496 patients) found no significant benefit of acyclovir: 71.2% recovery with acyclovir versus 75.7% without acyclovir (adjusted P=0.50 at 3 months) 3, 4
• At 9 months, acyclovir showed 85.4% recovery versus 90.8% without acyclovir 4

The American Academy of Otolaryngology-Head and Neck Surgery classifies combination therapy as an "option" rather than a recommendation, emphasizing a large role for shared decision-making 6, 1

Critical Pitfalls to Avoid

• Never prescribe acyclovir alone—it is ineffective as monotherapy and delays appropriate steroid treatment 6, 1
• Do not initiate steroids beyond 72 hours—clinical trials demonstrating benefit specifically enrolled patients within this window, and later treatment provides no proven benefit 1, 2
• Avoid standard methylprednisolone dose packs—they provide only 105 mg prednisone equivalent versus the required 540 mg over 14 days, representing significant underdosing 1
• Do not delay treatment for diagnostic testing—routine laboratory tests and imaging are not indicated and only delay effective therapy 1

Mandatory Eye Protection Protocol

All patients with impaired eye closure require immediate aggressive eye protection to prevent corneal damage 1:

• Lubricating ophthalmic drops every 1-2 hours while awake 1
• Ophthalmic ointment at bedtime for sustained moisture 1
• Eye taping or patching at night with proper technique instruction to avoid corneal abrasion 1
• Sunglasses outdoors for protection against wind and debris 1

Special Population Considerations

Diabetic Patients

Diabetes is NOT a contraindication to corticosteroid therapy—the therapeutic benefit outweighs the risk of temporary hyperglycemia 1:

• Monitor capillary blood glucose every 2-4 hours during the first few days 1
• Administer steroids in the morning to align with natural cortisol rhythm 1
• Proactively increase basal insulin and add or increase prandial insulin as needed 1

Pregnant Women

• Treat with oral corticosteroids within 72 hours using individualized assessment of benefits and risks 6, 1
• Combination therapy with antivirals may be considered on an individualized basis 1

Pediatric Patients

• Children have better prognosis with 80-90% spontaneous recovery rates 5
• Evidence for steroid benefit in children is inconclusive, though treatment may be offered with substantial caregiver involvement in shared decision-making 5
• Dosing: Prednisolone 1 mg/kg/day (maximum 50-60 mg) for 5-10 days followed by a 5-day taper 5

Follow-Up and Referral Triggers

Refer to a facial nerve specialist if 1:

• Incomplete facial recovery at 3 months after symptom onset
• New or worsening neurologic findings at any point
• Development of ocular symptoms at any time