What is the recommended dose of valacyclovir (Valtrex) for treating fever blisters (cold sores)?

Recommended Dosage of Valacyclovir for Fever Blisters (Cold Sores)

The recommended dosage of valacyclovir (Valtrex) for treating fever blisters (cold sores) is 2 grams twice daily for 1 day, taken 12 hours apart. 1

Evidence-Based Dosing Recommendation

The FDA-approved dosing for valacyclovir in the treatment of cold sores (herpes labialis) is clear and specific:

• 2 grams twice daily for 1 day (total daily dose: 4 grams)
• The two doses should be taken 12 hours apart
• Treatment should be initiated at the earliest symptom of a cold sore (e.g., tingling, itching, or burning) 1

This short-course, high-dose regimen has been shown to be effective in clinical trials and offers a convenient dosing alternative compared to other available therapies.

Clinical Evidence Supporting This Regimen

Two randomized, double-blind, placebo-controlled studies have demonstrated that this 1-day valacyclovir regimen is effective for treating cold sores:

• The median duration of cold sore episodes was reduced by 1.0 day (p=0.001) with the 1-day treatment compared to placebo 2
• The treatment helped prevent or block cold sore lesion development in some patients 2
• The time to lesion healing and time to cessation of pain were significantly reduced compared to placebo 2

Advantages of Valacyclovir Over Other Options

Valacyclovir offers several advantages over other antiviral medications:

• Better oral absorption than acyclovir, with 3-5 times greater bioavailability 2
• Simpler dosing regimen (twice daily for just one day) compared to other oral therapies 2
• Convenient administration that may improve patient adherence 3

Important Clinical Considerations

1. Timing of treatment: Initiation of therapy at the earliest symptom (prodrome) of a cold sore is crucial for maximum effectiveness 1

2. Renal adjustment: For patients with impaired renal function, dosage adjustments are necessary:

   • Creatinine clearance 30-49 mL/min: No reduction needed
   • Creatinine clearance 10-29 mL/min: 1 gram every 24 hours
   • Creatinine clearance <10 mL/min: 500 mg every 24 hours 1

3. Safety profile: Valacyclovir is generally well-tolerated, with a safety profile similar to placebo in clinical trials 2

Special Populations

• Children and adolescents: The same dosage (2 grams twice daily for 1 day) is recommended for pediatric patients ≥12 years of age 1
• Hemodialysis patients: Should receive the recommended dose after hemodialysis 1

Patient Education

Patients should be advised to:

• Begin treatment at the first sign of a cold sore (tingling, itching, or burning)
• Take the full prescribed dose even if symptoms begin to improve
• Avoid close contact with others during active lesions to prevent transmission

By following this evidence-based dosing regimen, patients can experience reduced duration and severity of cold sore episodes with a convenient, short-course treatment option.