Medically reviewed by Michele Emery, DNP
Written by Our Editorial Team
Last updated 6/10/2019
Valacyclovir is one of the most common and effective medications used to manage HSV-1 and HSV-2, two variants of the herpes simplex virus. While valacyclovir (commonly sold as Valtrex) provides treatment for and management of herpes symptoms, it’s not a cure for the virus.
However, can it also act as a way of preventing herpes transmission? Scientific data shows that while valacyclovir is helpful in reducing the risk of herpes transmission, it isn’t a 100% effective drug for preventing herpes entirely.
In this guide, we’ll look at some of the study data on valacyclovir’s effectiveness for preventing herpes transmission, as well as how the drug can be used to reduce your risk of infecting other people if you have HSV-1 or HSV-2.
If you have herpes, you’ve probably taken valacyclovir before as part of an outbreak or initial infection treatment protocol. Valacyclovir is extremely helpful in the management of herpes. During an outbreak, it can speed up the rate of recovery and quickly remove herpes sores.
When it comes to preventing the transmission of herpes, valacyclovir can be helpful but shouldn’t be relied on as a 100% effective solution.
Study data shows that people with symptomatic herpes who take valacyclovir are almost 50% less likely to transmit the virus to others than non-medicated people with herpes. In one study, the HSV-2 acquisition rate was reduced from 3.6% to 1.9% using valacyclovir treatment.
Other studies show a similar reduction in herpes transmission rates when the infected person used valacyclovir.
For example, in a 2004 study, researchers noticed that people with non-symptomatic genital herpes were 50% less likely to transfer the virus to their sexual partner. People with herpes symptoms had an even higher drop in transmission rate—a reduction of 77 percent.
It’s important to remember that this still means there are cases where herpes is transmitted between sexual partners, even when the infected person takes valacyclovir.
In short, while valacyclovir doesn’t completely block genital herpes transmission through sex and genital contact, using valacyclovir does lower your risk of catching herpes from a sexual partner.
If you have genital herpes, it’s important that you take steps to reduce your risk of transmitting the virus to your sexual partners. This is important even if your genital herpes is asymptomatic, meaning you don’t have any visible symptoms.
Our guide to how herpes is transmitted covers more about how herpes can spread between one sexual partner and another. In general, to lower your risk of transmitting herpes to other people, you’ll want to:
Use medication such as valacyclovir, which is proven to reduce the risk of transmission between sexual partners, or alternative medications such as acyclovir and famciclovir.
Use a condom to reduce the risk of contact with herpes sores and lesions, especially if you’re currently experiencing or have recently experienced a herpes outbreak.
Avoid having sex during a herpes outbreak, when the risk of transmission from exposure to the herpes lesions is highest.
Used effectively, condoms and medications such as valacyclovir, acyclovir and famciclovir can reduce the risk of female sexual partners developing herpes from an infected partner from 10% to 5% annually (men have a lower risk of contracting herpes from a female sexual partner).
Despite this, it’s still important to remember that there is some risk of transmission, even if you use condoms and medications like valacyclovir. As such, it’s essential that you’re open, honest and clear with your partner about your condition and the potential risk of infection.
If you want to know more about standard valacyclovir dosage or valacyclovir side effects you might experience, our Valacyclovir 101 guide is an excellent resource.