Valacyclovir for Reducing Herpes Transmission to Partners
Daily valacyclovir (Valtrex) at a dose of 500 mg significantly reduces the risk of transmitting genital herpes to partners by approximately 48%, with an even greater reduction (75%) in clinical disease transmission. 1
Recommended Dosing for Transmission Reduction
The FDA-approved dosage of valacyclovir specifically for reducing transmission of genital herpes is:
- 500 mg once daily for the source partner with a history of 9 or fewer recurrences per year 2
This dosing regimen is supported by clinical evidence showing that valacyclovir suppressive therapy effectively reduces viral shedding and transmission risk.
Mechanism of Transmission Reduction
Valacyclovir works to reduce transmission through several mechanisms:
- Suppresses viral replication
- Reduces frequency of symptomatic recurrences by 70-80% 3
- Decreases asymptomatic viral shedding 3
- Lowers the risk of transmitting HSV-2 infection to uninfected partners 1
Evidence Supporting Transmission Reduction
The International Herpes Management Forum (IHMF) recommends suppressive valacyclovir therapy for immunocompetent individuals concerned about transmitting genital herpes to heterosexual partners 1. This recommendation is based on a large randomized, placebo-controlled study of 1,484 immunocompetent heterosexual couples that demonstrated:
- 48% reduction in risk of HSV-2 transmission with daily valacyclovir (500 mg) 1
- 75% reduction in risk of clinical disease in susceptible partners 1
Dosing Considerations Based on Recurrence Frequency
The appropriate dosing depends on the frequency of recurrences:
- For patients with <10 recurrences per year: 500 mg valacyclovir once daily is effective 4
- For patients with ≥10 recurrences per year: 1 gram valacyclovir once daily, 250 mg twice daily, or 400 mg acyclovir twice daily may be more effective 4
- For HIV-infected patients with CD4+ count ≥100 cells/mm³: 500 mg twice daily is recommended 2
Important Considerations and Precautions
Renal function adjustment: Dosage should be adjusted for patients with impaired renal function 2
Duration of therapy: After 1 year of continuous suppressive therapy, treatment should be discontinued to reassess recurrence rate 3
Additional prevention measures: Even while on suppressive therapy, patients should:
- Abstain from sexual activity while lesions are present
- Use condoms during all sexual exposures
- Inform partners about HSV status 3
Safety profile: Valacyclovir is well tolerated at dosages used for suppression of genital herpes (500-1000 mg/day) with headache being the most commonly reported side effect 5
Practical Implementation
For patients concerned about transmitting genital herpes to partners:
- Determine recurrence frequency (per year)
- Assess renal function
- Prescribe appropriate valacyclovir dosage
- Counsel on additional prevention measures
- Reassess after 1 year of continuous therapy
While valacyclovir significantly reduces transmission risk, it's important to note that it does not completely eliminate the risk of transmission. The combination of suppressive therapy and safer sex practices provides the most comprehensive approach to preventing transmission.