What is the recommended dose of valacyclovir (Valtrex) for an adult patient with a history of recurrent herpes simplex virus (HSV) 1 and 2 infections?

Valacyclovir Dosing for Recurrent HSV-1 and HSV-2

Episodic Treatment of Recurrent Outbreaks

For recurrent episodes of HSV-1 or HSV-2, the recommended dose is valacyclovir 500 mg twice daily for 3-5 days, initiated at the first sign or symptom of an outbreak. 1, 2

• The FDA-approved regimen for recurrent genital herpes is 500 mg twice daily for 3 days 2
• The CDC supports extending treatment to 5 days (500 mg twice daily) as an alternative regimen 1
• Treatment must be initiated at the earliest symptom (tingling, itching, burning) for maximum efficacy 1, 2

Chronic Suppressive Therapy

For patients requiring daily suppression, the dose depends on recurrence frequency:

Standard Suppression (≤9 recurrences per year)

• Valacyclovir 500 mg once daily is the recommended dose for immunocompetent patients with infrequent recurrences 1, 2
• This regimen reduces recurrence frequency by ≥75% 1

High-Frequency Suppression (≥10 recurrences per year)

• Valacyclovir 1000 mg (1 gram) once daily is necessary for patients with frequent recurrences 1, 3, 2
• The 500 mg once-daily dose is significantly less effective in this population and should not be used 1, 3, 4

Special Populations

HIV-Infected Patients

• For HIV-infected patients with CD4+ count ≥100 cells/mm³, use valacyclovir 500 mg twice daily for suppressive therapy 1, 3, 2
• Episodic treatment requires 5-14 days (not the 1-3 day short-course regimens used in immunocompetent patients) 3

Transmission Reduction

• Valacyclovir 500 mg once daily reduces HSV-2 transmission to uninfected partners by 50% in source partners with ≤9 recurrences per year 3

Clinical Considerations

Duration and Monitoring

• Safety and efficacy have been documented for up to 1 year with valacyclovir 1
• After 1 year of continuous suppressive therapy, consider discussing discontinuation to reassess recurrence frequency, as recurrences may decrease over time 1
• No laboratory monitoring is needed unless substantial renal impairment exists 1, 3

Renal Dosing

• For creatinine clearance 30-49 mL/min, no dose reduction is required 1
• Patients with significant renal impairment require dose adjustment and monitoring 1

Treatment Failure

• If lesions persist despite appropriate valacyclovir treatment, suspect HSV resistance 1
• All acyclovir-resistant strains are also resistant to valacyclovir 1, 3
• For acyclovir-resistant HSV, IV foscarnet (40 mg/kg every 8 hours) is the treatment of choice 1

Common Pitfalls to Avoid

• Do not use 500 mg once daily for patients with ≥10 recurrences per year – this dose is inadequate and will result in breakthrough recurrences 1, 3, 4
• Do not use short 1-3 day episodic regimens in HIV-infected patients – they require 5-14 days of treatment 3
• Do not use high-dose valacyclovir (8 g/day) in immunocompromised patients – this has been associated with thrombotic thrombocytopenic purpura/hemolytic uremic syndrome 1, 5
• Suppressive therapy reduces but does not eliminate asymptomatic viral shedding 1