Valacyclovir Dosing for Herpes Infections
The recommended dosing for valacyclovir (Valtrex) varies by type of herpes infection: 2 grams twice daily for 1 day for cold sores, 1 gram twice daily for 10 days for initial genital herpes, 500 mg twice daily for 3 days for recurrent genital herpes, and 1 gram three times daily for 7 days for herpes zoster. 1
Dosing by Herpes Type
Cold Sores (Herpes Labialis)
- Dosage: 2 grams twice daily for 1 day (taken 12 hours apart)
- Timing: Initiate at earliest symptom (tingling, itching, or burning)
- Population: Adults and pediatric patients ≥12 years 1
Genital Herpes
Initial Episode:
- 1 gram twice daily for 10 days
- Most effective when started within 48 hours of symptom onset 1
Recurrent Episodes:
Suppressive Therapy:
Reduction of Transmission:
- 500 mg once daily for source partner (with history of ≤9 recurrences per year) 1
Herpes Zoster (Shingles)
- 1 gram three times daily for 7 days
- Initiate at earliest sign or symptom
- Most effective when started within 48 hours of rash onset 1
Special Populations
Pediatric Patients
- Cold sores: 2 grams twice daily for 1 day (≥12 years)
- Chickenpox: 20 mg/kg three times daily for 5 days (ages 2 to <18 years)
- Maximum dose: 1 gram three times daily 1
Renal Impairment
- Dosage adjustment required based on creatinine clearance
- For patients on hemodialysis, administer after dialysis on dialysis days 1
Immunocompromised Patients
- May require longer treatment duration and closer monitoring 4
- For CMV prophylaxis in transplant patients, higher doses (2 g four times daily) have been studied, but carry risk of thrombotic microangiopathy with prolonged use 5
Administration Considerations
- May be given without regard to meals
- Oral suspension (25 mg/mL or 50 mg/mL) can be prepared from 500-mg tablets for pediatric patients 1
- Once-daily dosing (1000 mg) has been shown to be equivalent to twice-daily dosing (500 mg) for recurrent genital herpes, improving convenience 2
Common Pitfalls and Caveats
- Initiate treatment as early as possible for maximum effectiveness
- Dosage must be adjusted in patients with renal impairment
- High-dose valacyclovir (8 g/day) in immunocompromised patients has been associated with thrombotic microangiopathy-like syndrome 5
- Valacyclovir provides better bioavailability than oral acyclovir, allowing for less frequent dosing 6
- For suppressive therapy, there is a dose-response relationship across once-daily regimens, with higher doses providing better suppression 3
Comparative Efficacy
- Valacyclovir 1 gram twice daily is as effective as acyclovir 200 mg five times daily for first-episode genital herpes 7
- For herpes zoster, valacyclovir is more effective than acyclovir in reducing the duration of zoster-associated pain 6
- For suppressive therapy, valacyclovir 500 mg once daily is effective for patients with <10 recurrences per year 3