What is the risk of spreading herpes simplex virus (HSV) while taking valtrex (valacyclovir) without visible lesions?

Risk of HSV Transmission While Taking Valacyclovir Without Visible Lesions

Daily valacyclovir significantly reduces but does not eliminate the risk of transmitting herpes simplex virus (HSV) when no lesions are present. 1, 2

Transmission Risk Reduction with Valacyclovir

• Valacyclovir 500 mg once daily reduces the risk of HSV-2 transmission by approximately 48% compared to placebo in heterosexual couples 1
• The medication works by significantly reducing viral shedding:
  • Reduces total HSV-2 shedding by 71% 2
  • Reduces subclinical (asymptomatic) shedding by 58% 2
  • Reduces clinical shedding by 64% 2

Asymptomatic Viral Shedding

• Sexual transmission of HSV has been documented to occur during periods without visible lesions 3
• Many HSV transmissions occur during asymptomatic periods 3
• Without suppressive therapy, asymptomatic viral shedding occurs on approximately:
  • 2-6% of days using viral culture methods 4
  • Up to 28% of days when measured by more sensitive PCR testing 4

Important Considerations

Effectiveness of Suppressive Therapy

• Daily suppressive therapy reduces HSV recurrences by at least 75% in people with frequent outbreaks 3
• Valacyclovir 1g daily can keep approximately 71% of patients recurrence-free at 24 weeks 5
• However, suppressive treatment does not totally eliminate viral shedding or the potential for transmission 3

Additional Prevention Measures

• Patients should be advised to:
  • Abstain from sexual activity while lesions are present 3
  • Use condoms during all sexual exposures, as they can reduce HSV-2 transmission 3
  • Inform sexual partners about their HSV status, as disclosure in heterosexual HSV-2-discordant couples was associated with reduced transmission risk 3

Special Populations

• For HIV-infected individuals:
  • Valacyclovir 500 mg twice daily is effective for suppression of recurrent genital herpes 6
  • Daily HSV suppressive therapy may decrease HIV concentration in plasma and genital secretions 7
  • Higher dosages may be needed (400 mg orally 3-5 times daily) 3

Clinical Implications

• Patients should understand that while valacyclovir significantly reduces transmission risk, it does not provide complete protection
• The combination of suppressive therapy with condom use and partner disclosure offers the most comprehensive approach to reducing transmission
• Regular follow-up is important to assess medication effectiveness and adherence

Remember that even with suppressive therapy, the risk of transmission is reduced but not eliminated, making honest communication with partners and additional preventive measures essential.