Valacyclovir Dosing for HSV Infections
For HSV infections, valacyclovir dosing depends on the clinical presentation: initial genital herpes requires 1 gram twice daily for 7-10 days, recurrent episodes require 500 mg twice daily for 3-5 days, and suppressive therapy requires 500-1000 mg once daily based on recurrence frequency. 1, 2, 3
Initial Genital Herpes Episode
- The CDC recommends valacyclovir 1 gram orally twice daily for 7-10 days for first-episode genital herpes. 1, 3
- Treatment is most effective when initiated within 48 hours of symptom onset and may be extended if healing is incomplete after 10 days. 1, 2
- Note that 5-30% of first-episode genital herpes cases are caused by HSV-1, though clinical recurrences are much less frequent for HSV-1 than HSV-2. 1
Recurrent Genital Herpes Episodes
- The FDA-approved dosing for recurrent episodes is 500 mg twice daily for 3 days. 3
- The CDC alternatively recommends 500 mg twice daily for 5 days, initiated at the first sign of prodrome or lesions. 2
- Patients should be provided with medication or a prescription in advance to enable immediate treatment initiation at the first sign of prodrome for maximum efficacy. 2
Suppressive Therapy (Chronic Daily Dosing)
For Immunocompetent Patients:
- The standard dose is 1 gram once daily for patients with normal immune function. 2, 4, 3
- For patients with infrequent recurrences (≤9 episodes per year), an alternative dose of 500 mg once daily is acceptable. 4, 3, 5
- However, 500 mg once daily is less effective in patients with ≥10 recurrences per year, who should receive 1 gram once daily. 4, 5
- Suppressive therapy reduces recurrence frequency by ≥75% among patients with frequent episodes. 2, 4
For HIV-Infected Patients:
- For HIV-infected patients with CD4+ count ≥100 cells/mm³, the CDC recommends 500 mg twice daily for suppressive therapy. 1, 4, 3
- Higher dosing is recommended for immunocompromised patients due to potentially more severe and frequent recurrences. 1, 4
Herpes Labialis (Cold Sores)
- The FDA-approved dose for cold sores is 2 grams twice daily for 1 day, taken 12 hours apart. 3
- Therapy should be initiated at the earliest symptom (tingling, itching, or burning). 3
Severe HSV Infections Requiring Hospitalization
- For severe disease with complications (disseminated infection, pneumonitis, hepatitis, or CNS involvement), use IV acyclovir 5-10 mg/kg every 8 hours for 5-7 days instead of oral valacyclovir. 1, 2
Critical Safety Considerations
- Avoid valacyclovir doses of 8 grams per day in immunocompromised patients due to risk of thrombotic thrombocytopenic purpura/hemolytic uremic syndrome (TTP/HUS). 1, 2, 4
- No laboratory monitoring is needed for patients on suppressive therapy unless they have substantial renal impairment. 4
- After 1 year of continuous suppressive therapy, consider discussing discontinuation to assess recurrence frequency, as recurrences may decrease over time. 4
Renal Dose Adjustments
- For creatinine clearance 30-49 mL/min: No dose reduction needed for most indications. 3
- For creatinine clearance 10-29 mL/min: Reduce to 500 mg every 24 hours for recurrent episodes; 1 gram every 24 hours for herpes zoster. 3
- For creatinine clearance <10 mL/min: Reduce to 500 mg every 24 hours for most indications. 3
Treatment Failure and Resistance
- If lesions persist despite appropriate valacyclovir treatment, consider HSV resistance. 1, 4
- All acyclovir-resistant HSV strains are also resistant to valacyclovir. 1, 2, 4
- For acyclovir-resistant HSV, IV foscarnet 40 mg/kg every 8 hours until clinical resolution is the treatment of choice. 1, 2, 4
Important Clinical Pearls
- Valacyclovir may be given without regard to meals. 3
- Suppressive therapy reduces but does not eliminate asymptomatic viral shedding, and transmission can occur even during asymptomatic periods. 2, 4
- Safety and efficacy have been documented for up to 6 years with acyclovir and 1 year with valacyclovir for suppressive therapy. 4