What is the recommended dosage of valacyclovir (Valtrex) for an adult patient experiencing a cold sore episode?

Valacyclovir Dosing for Cold Sore Episodes

For an adult experiencing a cold sore episode, the recommended dose of valacyclovir 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) for maximum effectiveness 2, 1
• Treatment should ideally begin during the prodromal phase or within 1 day after onset of lesions 2
• The 1-day high-dose regimen is FDA-approved specifically for cold sores (herpes labialis) in adults and adolescents aged ≥12 years 1

Evidence Supporting This Regimen

• This high-dose, short-duration regimen reduces the median duration of cold sore episodes by approximately 1 day compared to placebo (statistically significant, P = 0.001) 3
• The mean episode duration is reduced by 1.1 days with the 1-day treatment 3
• Time to lesion healing and time to cessation of pain/discomfort are significantly reduced compared to placebo 3
• The proportion of patients in whom cold sore lesion development was prevented or blocked increased by 6.4% compared to placebo 3

Clinical Advantages

• Valacyclovir offers superior bioavailability compared to acyclovir (3- to 5-fold increase), allowing for the high-dose, convenient dosing regimen 3, 4
• The 1-day regimen provides a unique and convenient dosing alternative compared to available topical therapies, which are substantially less effective than systemic therapy 3
• The regimen is well-tolerated, with adverse events similar to placebo 3

Administration Details

• Valacyclovir may be given without regard to meals 1
• The total treatment consists of only 2 doses: one dose of 2 grams, followed 12 hours later by a second dose of 2 grams 1
• Do not exceed 1 day of treatment 1

Renal Dosing Adjustments

For patients with renal impairment treating cold sores 1:

• Creatinine clearance 30-49 mL/min: 1 gram every 12 hours (do not exceed 1 day)
• Creatinine clearance 10-29 mL/min: 1 gram every 24 hours
• Creatinine clearance <10 mL/min: 500 mg every 24 hours
• Hemodialysis patients: Administer the recommended dose after hemodialysis

Important Caveats

• This specific 2-gram twice-daily regimen is only for cold sores (herpes labialis), not for genital herpes or herpes zoster, which require different dosing schedules 1
• The American College of Obstetricians and Gynecologists specifically endorses this 2-gram twice-daily for 1 day regimen for oral herpes 2
• Topical antiviral therapy is not recommended as it is substantially less effective than systemic therapy 5