Valacyclovir
Sexual Well-Being
In plain English
Valacyclovir is an antiviral pill used to treat and prevent genital herpes outbreaks. Taken daily, it can also lower the chance of passing herpes to a partner. It is FDA-approved and well studied. It is taken by mouth and is generally well tolerated.
The science
Valacyclovir is an oral prodrug of acyclovir with markedly improved bioavailability; after absorption it is converted to acyclovir, which is selectively phosphorylated by viral thymidine kinase and inhibits herpesvirus DNA polymerase to halt viral replication. It is FDA-approved for genital herpes (episodic and suppressive therapy) and other herpesvirus infections. A landmark randomized trial (Corey 2004) showed once-daily valacyclovir 500 mg in the infected partner reduced transmission of symptomatic genital herpes to susceptible partners by ~75% and overall HSV-2 acquisition by ~48%, alongside reduced recurrences and subclinical shedding. It is generally well tolerated (headache, nausea); dose adjustment is required in renal impairment, and thrombotic thrombocytopenic purpura/hemolytic uremic syndrome has been reported at very high doses in severely immunocompromised patients. This is an FDA-approved oral medication used within sexual-health care.