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

Valacyclovir Dosing for Cold Sores

The recommended dose of valacyclovir for cold sores (herpes labialis) is 2 grams twice daily for 1 day, with the two doses taken 12 hours apart. 1

Treatment Initiation and Timing

• Therapy must be initiated at the earliest symptom of a cold sore (tingling, itching, or burning) to achieve maximum efficacy 1, 2
• Treatment started during the prodromal phase or within the first hours of lesion appearance provides the greatest benefit 2
• Early initiation is the single most important factor determining treatment success 3

Clinical Efficacy

• This 1-day regimen significantly reduces the median duration of cold sore episodes to 4.0-5.0 days compared to 5.0 days with placebo (p <0.001) 4, 2
• The treatment reduces healing time, decreases pain associated with lesions, and may potentially prevent lesion development when started during prodrome 2
• In clinical trials, the mean duration of episodes was reduced by 1.1 days with the 1-day treatment compared to placebo 5

Dosing Adjustments for Renal Impairment

For patients with reduced kidney function, adjust the single-day regimen as follows 1:

• CrCl ≥50 mL/min: 2 grams every 12 hours (standard dose)
• CrCl 30-49 mL/min: 1 gram every 12 hours
• CrCl 10-29 mL/min: 1 gram every 24 hours
• CrCl <10 mL/min: 500 mg every 24 hours

Important: Do not exceed 1 day of treatment regardless of renal function 1

Administration Details

• Valacyclovir may be given without regard to meals 1
• The two doses should be separated by exactly 12 hours 1
• For pediatric patients ≥12 years, use the same adult dosing regimen of 2 grams twice daily for 1 day 1

Safety Profile

• Valacyclovir is generally well-tolerated for cold sore treatment 2
• Common adverse events include headache, nausea, and gastrointestinal complaints, with no serious adverse events reported in clinical studies 2
• The safety profile is similar to placebo in herpes labialis trials 5, 6

Key Clinical Pitfalls to Avoid

• Do not delay treatment: Waiting until lesions are fully developed significantly reduces efficacy 2, 3
• Do not extend treatment beyond 1 day in immunocompetent patients: The approved regimen is specifically designed as a single-day treatment 1
• Do not use lower doses: The 2-gram dose is specifically required for cold sores; lower doses used for genital herpes suppression are not appropriate for herpes labialis 1
• Do not forget renal dose adjustments: Failure to adjust for renal impairment can lead to toxicity 1