Valacyclovir (Valtrex) Dosing for Herpes Simplex Virus Infections
For genital herpes, use valacyclovir 1 gram twice daily for 7-10 days for initial episodes, 500 mg twice daily for 3-5 days for recurrent episodes, and 500-1000 mg once daily for suppressive therapy depending on recurrence frequency. 1
Initial Episode of Genital Herpes
The FDA-approved dose is 1 gram twice daily for 10 days, with treatment most effective when started within 48 hours of symptom onset. 1
- Therapy may be extended beyond 10 days if healing is incomplete 2
- This regimen has been shown equivalent in efficacy to acyclovir 200 mg five times daily 3, 4
Recurrent Episodes
For episodic treatment of recurrences, use 500 mg twice daily for 3 days, initiated at the first sign or symptom of an episode. 1
- Alternative regimens include 500 mg twice daily for 5 days, which is equally effective 5, 6
- Treatment is most beneficial when started during prodrome or within 1 day of lesion onset 5
- A once-daily 1000 mg dose for 5 days is therapeutically equivalent to 500 mg twice daily 6
Suppressive Therapy
For chronic suppression in immunocompetent patients, use 1 gram once daily; for those with 9 or fewer recurrences per year, 500 mg once daily is an acceptable alternative. 1
- Daily suppressive therapy reduces recurrence frequency by ≥75% in patients with frequent episodes 7
- The 500 mg once-daily dose is less effective in patients with ≥10 episodes per year 5, 7
- Safety and efficacy documented for up to 6 years with acyclovir and 1 year with valacyclovir 5
- After 1 year of continuous therapy, consider discontinuation to reassess recurrence rate, as frequency often decreases over time 7
Special Populations
For HIV-infected patients with CD4+ count ≥100 cells/mm³, use 500 mg twice daily for suppressive therapy. 7, 1
- Higher dosing is recommended for immunocompromised patients due to more severe and frequent recurrences 7
- Avoid doses of 8 grams per day in immunocompromised patients due to risk of thrombotic thrombocytopenic purpura/hemolytic uremic syndrome. 7, 8
Cold Sores (Herpes Labialis)
For cold sores in patients ≥12 years, use 2 grams twice daily for 1 day, taken 12 hours apart. 1
- Initiate at the earliest symptom (tingling, itching, or burning) 1
Severe Disease
For severe HSV requiring hospitalization (disseminated infection, encephalitis, pneumonitis, hepatitis), use IV acyclovir 5-10 mg/kg every 8 hours for 5-7 days instead of oral valacyclovir. 5, 2
Renal Dosing
No dose reduction is needed for creatinine clearance 30-49 mL/min, but caution and potential adjustment are required for more severe renal impairment. 7, 9
- No laboratory monitoring is needed for patients on suppressive therapy unless substantial renal impairment exists 7
Treatment Failure and Resistance
If lesions persist after 7-10 days of appropriate valacyclovir therapy, consider HSV resistance. 7
- All acyclovir-resistant strains are also resistant to valacyclovir 7, 2
- For acyclovir-resistant HSV, IV foscarnet 40 mg/kg every 8 hours until clinical resolution is the treatment of choice. 7, 2
Important Clinical Considerations
- Valacyclovir may be given without regard to meals 1
- Suppressive therapy reduces but does not eliminate asymptomatic viral shedding 7
- Valacyclovir provides 3-5 fold better oral bioavailability than acyclovir, allowing more convenient dosing 8, 10
- Headache is the most commonly reported adverse effect at standard doses 8