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Pictured above: From http://www.nitrd.gov/PUBS/bluebooks/1994/section.4.5.html

Q: Can I catch herpes if my partner isn’t having an outbreak?
A: Yes, your partner can transmit the virus even if he or she isn’t experiencing symptoms. In fact, most genital herpes infections are transmitted in the absence of symptoms.

When most people think about genital herpes, they think about the symptoms that are associated with it: clusters of blistery sores around the genitals or buttocks. But most genital herpes infections don’t have symptoms — they are asymptomatic — or the symptoms are so mild or nonspecific that the person suffering from them doesn’t even make the mental connection. It is estimated that only 10 to 15 percent of people with herpes exhibit symptoms, which may be a silver lining for the millions who unknowingly carry the virus, but it also helps it spread more easily.

What is genital herpes, anyway?

Genital herpes can be caused by two types of herpes simplex viruses — either herpes simplex virus type 1 (HSV-1) or herpes simplex virus type 2 (HSV-2). The difference between the two viruses is that HSV-1 is more active when it infects the facial region, where it can cause cold sores; HSV-2 is more active when it infects the genitals. Genital infections with HSV-1 tend to be milder than genital infections with HSV-2. The Centers for Disease Control and Prevention states that, among Americans 14 to 49 years old, 1 out of 5 women and 1 out of 9 men have a genital HSV-2 infection. Because that stat doesn’t count genital HSV-1 infections, the overall number of people with genital herpes is actually higher.

An “outbreak” occurs when genital herpes symptoms appear. The most well-known symptom is a cluster of blisters or open sores in the genital or rectal area. Other symptoms, which might be mild or might not be recognized as being part of an infection, include:

  • very small lesions
  • itching
  • soreness
  • genital pain
  • tingling or shooting pains below the waist
  • during the first outbreak: flu-like feeling, fever, chills, or swollen glands

These symptoms are very common, and we could experience any of them on any day for a number of reasons, so it’s quite possible for someone to experience them as a result of a genital herpes infection but not make the connection. Some people with herpes infections learn to recognize these subtle cues to better predict when the virus is flaring up, which could help them avoid transmitting the virus to their partners.

How is herpes spread without an outbreak?

People infected with HSV periodically go through phases in which they are “shedding” the virus, meaning that their bodies are producing infectious virus particles that can be transmitted to others through close contact. HSV can originate from a number of places, including the vulvacervixpenile skin, scrotal areaurethra, anal area, feces, urine, and semen.

When someone infected with HSV experiences genital blisters or sores, he or she is certainly shedding virus as well. But the virus can also replicate silently, meaning that you don’t experience symptoms but you do produce copies of the virus, which you can potentially transmit. It’s much more common to shed virus when no genital lesions are present — this phenomenon is called asymptomatic shedding.

About 75 percent of asymptomatic shedding events only last for a day, while viral shedding lasts longer when accompanied by symptoms. Asymptomatic shedding is partially influenced by a few factors:

  • HSV type: A genital HSV-1 infection is milder than a genital HSV-2 infection. Genital HSV-1 infections have fewer recurrences and are associated with less asymptomatic shedding.
  • Duration of infection: While it’s thought that viral shedding never ceases completely, the rate does seem to decrease over time. Someone who has been infected with HSV for many years probably sheds less virus than someone who has recently acquired the infection.
  • Immune status: A compromised immune system might increase the rate at which someone with an HSV infection sheds virus. For example, people with HIV might shed HSV at a higher rate than their HIV-negative counterparts.

Older studies on asymptomatic shedding relied on a technique called “viral culture” to detect HSV from subjects, and found that people with herpes infections were asymptomatically shedding on around 1 to 4 percent of days. Recently, however, researchers started using PCR, a highly sensitive technology that can “amplify” DNA from very small sample sizes — and they are finding higher rates of asymptomatic shedding. For instance, one team found that females with recent HSV-2 genital infections shed virus on 28 percent of days on average. Males with recent HSV-2 genital infections, or a history of frequent herpes outbreaks, were found to shed virus on 32 percent of days on average. Other studies have had similar findings.

The rate of asymptomatic shedding varies from individual to individual. Thanks to genetic variation, our immune systems are all different, and there are even slight genetic differences between HSV strains, leading to unique host/virus interactions. Unless we are being studied by herpes researchers, we can’t know for sure how often we are asymptomatically shedding.

If I have genital herpes, how can I protect my partner?

Most HSV transmissions occur during periods of asymptomatic shedding, but there are still preventive steps you can take. If you have a genital HSV infection, you can:

  • use condoms consistently and correctly, if you or your partner has a penis
  • use dental dams for cunnilingus or anilingus if the giving partner has an oral HSV infection, or if the receiving partner has a genital HSV infection
  • consider herpes medications, such as acyclovir or valacyclovir, which decrease rates of asymptomatic shedding (and outbreaks!)
  • seek education from a sexual health provider, who can help you recognize mild or atypical herpes outbreaks
  • in the event of symptoms, practice abstinence until seven days after genital lesions have healed

Need more information? Make an appointment at a Planned Parenthood health center to be tested for HSV or to learn about safer sex, herpes medication, and more. And drop by any time to pick up latex condoms, female condoms, and dental dams!

Tags: dental dams, cold sores, condom, HSV, genital herpes, sexually transmitted infections, HSV-2, infection, STI, abstinence, sexual health, herpes, STD Awareness

About Anna C.

Anna first volunteered for Planned Parenthood as a high school student in the 1990s. Since then, she has received a bachelor’s degree from UC Berkeley and a master's degree in epidemiology from the University of Arizona. As an ode to her fascination with microbes, she writes the monthly STD Awareness series, as well as other pieces focusing on health and medicine.