Valacyclovir Dosing for Herpes Infections
The recommended dose of valacyclovir depends on the specific herpes infection being treated: for genital herpes initial episodes use 1 gram twice daily for 10 days, for recurrent genital herpes episodes use 500 mg twice daily for 3 days, for suppressive therapy use 1 gram once daily (or 500 mg once daily if ≤9 recurrences per year), for cold sores use 2 grams twice daily for 1 day (12 hours apart), and for herpes zoster (shingles) use 1 gram three times daily for 7 days. 1
Genital Herpes (HSV) Dosing
Initial Episode
- 1 gram twice daily for 10 days is the FDA-approved dose for first episodes of genital herpes 1
- Treatment is most effective when initiated within 48 hours of symptom onset 1
Recurrent Episodes
- 500 mg twice daily for 3 days is the standard treatment for recurrent genital herpes 1
- Initiate treatment at the first sign or symptom of an episode 1
- Alternative regimen: 1 gram once daily for 5 days is equally effective 2
Suppressive Therapy
- 1 gram once daily for patients with frequent recurrences (≥10 episodes per year) 3, 1
- 500 mg once daily for patients with 9 or fewer recurrences per year 3, 1
- The 500 mg once daily dose is less effective in patients with ≥10 recurrences per year and should not be used in this population 3
- Suppressive therapy reduces recurrences by ≥75% and has documented safety for up to 1 year 3
HIV-Infected Patients
- 500 mg twice daily for suppressive therapy in HIV-infected patients with CD4+ count ≥100 cells/mm³ 3, 1
- Higher dosing is recommended due to potentially more severe and frequent recurrences 3
Cold Sores (Herpes Labialis)
- 2 grams twice daily for 1 day (doses taken 12 hours apart) 1
- Therapy should be initiated at the earliest symptom (tingling, itching, or burning) 1
- This regimen is approved for patients ≥12 years of age 1
Herpes Zoster (Shingles)
- 1 gram three times daily for 7 days is the standard FDA-approved dose 1
- Therapy should be initiated within 48-72 hours of rash onset for optimal efficacy 4, 1
- Treatment should continue until all lesions have scabbed, which may require extension beyond 7 days in some patients 4
- Alternative dosing: 1.5 grams twice daily has been shown to be safe and effective, potentially improving compliance 5
Immunocompromised Patients with Herpes Zoster
- Consider intravenous acyclovir 10 mg/kg every 8 hours for disseminated disease, severe immunosuppression, or CNS complications 4, 6
- Oral valacyclovir may require higher doses or extended duration in immunocompromised patients 4
Special Populations and Considerations
Renal Impairment
- No dose adjustment needed for creatinine clearance (CrCl) 30-49 mL/min 3
- For CrCl <30 mL/min: 500 mg every 24-48 hours for suppressive therapy 6
- For hemodialysis patients: 500 mg after each dialysis session 6
Transmission Reduction
- 500 mg once daily for source partners with history of ≤9 recurrences per year to reduce transmission to uninfected partners 1
- Suppressive therapy reduces but does not eliminate asymptomatic viral shedding 3
Critical Safety Warnings
- Avoid 8 grams per day in immunocompromised patients due to risk of thrombotic thrombocytopenic purpura/hemolytic uremic syndrome (TTP/HUS) 3, 7
- High-dose valacyclovir (8 g/day) has been associated with increased mortality in advanced HIV disease and should be avoided 7
- Ensure adequate hydration to minimize nephrotoxicity risk 3
- Monitor renal function closely during therapy, especially with high doses or in patients with renal impairment 4
Treatment Resistance
- All acyclovir-resistant HSV strains are also resistant to valacyclovir 3, 6
- If lesions persist despite appropriate therapy for 7-10 days, consider HSV resistance 3
- Foscarnet 40 mg/kg IV every 8 hours until clinical resolution is the treatment of choice for acyclovir-resistant HSV 3, 6