Asymptomatic herpes: what you need to know

Herpes is one of the world’s most common sexually transmitted infections (STI). An estimated 12% of Americans aged 14 to 49 years are infected with the virus that predominantly causes genital herpes, and these numbers might even be higher depending on what herpes virus you look at (McQuillan, 2018). With numbers like that, you may wonder if it’s possible to have herpes and not know it. Unfortunately, it is possible, and asymptomatic herpes is one way this infection spreads so easily. In fact, the Centers for Disease Control and Prevention (CDC) say most people with genital herpes infection do not know they have it.

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Asymptomatic herpes describes a herpes infection that does not come with any symptoms. Common symptoms of herpes include (Mathew, Jr., 2021; Saleh, 2021):

• Itching, burning, or tingling around the mouth, lips, or genital area

• Blisters or cold sores that may develop into pus-filled lesions

• Fatigue

• Pain while urinating

The symptoms of herpes are typically worse during the initial outbreak, which can last for two to six weeks. Subsequent herpes outbreaks are usually milder (Mathew, Jr., 2021; Saleh, 2021). While some people first experience symptoms fairly quickly, within hours to days after exposure, it may take longer for symptoms to develop (Saleh, 2021; Groves, 2016). 

But, many herpes infections are asymptomatic, meaning many people contract herpes and don’t experience any of these symptoms or have mild symptoms that go unrecognized (Feltner, 2016; Shannon, 2014).

There are many different types of herpes viruses, but when you hear “herpes,” you’re likely thinking of two types of the herpes simplex virus: herpes simplex virus type 2 (HSV-2) and herpes simplex virus type 1 (HSV-1), two viruses that can cause sores on your genitals and mouth.

HSV-2 infections typically cause genital herpes, while HSV-1 infections typically cause oral herpes, also known as cold sores. However, either virus can cause either type of herpes. Once you have HSV-1 or HSV-2, you’ll have it for life. Most of the time, you won’t have any symptoms, but from time to time, you can have outbreaks. HSV-2 outbreaks tend to occur more frequently, while HSV-1 outbreaks are milder (Groves, 2016).

Yes, you can have herpes and not know it. Most people with genital herpes do not experience symptoms and may not know they have herpes. It’s also possible to have oral herpes and not know it. Many people get oral herpes in childhood and have fewer symptomatic outbreaks, if any, so they may never know they have it. Almost half of Americans aged 14 to 49 are infected with HSV-1 (Shannon, 2014; Feltner, 2016; McQuillan, 2018). 

Experts estimate around 65% to 90% of people with genital herpes are unaware that they have it (Groves, 2016). 

However, people with asymptomatic herpes can still pass herpes to other people. In fact, most infections pass asymptomatically (Schiffer, 2014). Herpes can be transmitted through saliva, kissing, oral sex, or genital-to-genital contact with an infected person, whether or not that person has a noticeable outbreak. A small number of pregnant women pass it on to their child, known as neonatal herpes (Saleh, 2021; Groves, 2016).

While it’s true that the risk of spreading herpes is greater when a person has signs of active infection, it is still contagious even without symptoms. People with an asymptomatic herpes infection shed the virus about half as often as people with symptomatic herpes (Tronstein, 2011).

It’s hard to nail it down to an exact number, because the risk of getting herpes hinges on a couple of things. As with other STIs, your chances of getting herpes go up according to how often you have sex, the number of sex partners you have, and how often condoms are used. Besides that, women are at a greater risk of contracting herpes than men (Groves, 2016). 

But there are some estimates about the likelihood of an asymptomatic person shedding the virus. According to one study, people with asymptomatic herpes shed the virus 10% of the days they were in the study, about half as often as those with symptomatic herpes (Tronstein, 2011). However, other studies have found that asymptomatic shedding can be as high as 20%. Herpes viral shedding may occur more often during the first year of infection (Groves, 2016). 

Oral antiviral medications for herpes include valacyclovir (Valtrex; see Important Safety Information), acyclovir, and famciclovir. 

Herpes is not curable, but medication can reduce your risk of experiencing an outbreak, as well as lower the risk of transmitting it to others. These medications can be used to shorten an episode when taken at the first sign or symptom of an outbreak. Or they can be used on an ongoing basis. For example, taking acyclovir on a long-term basis, also known as suppressive therapy, can prevent up to 80% of outbreaks and reduce shedding by over 90%. Using condoms and sharing your status with your sexual partners can also reduce the risk of transmission (Tronstein, 2011; Mathew, Jr., 2021).

If you think you may have herpes, the best way to find out is by taking a blood test that looks for the presence of antibodies or the virus itself. The viral test can also identify whether you have an HSV-1 or HSV-2 herpes infection (Saleh, 2021; Feltner, 2016). It can take a couple of weeks for HSV antibodies to form and be detectable, so you may want to wait at least that long after an exposure to get the most accurate results or take a second test to be sure (Groves, 2016). 

If you think you have herpes, either because you were exposed or have symptoms, contact your healthcare provider and avoid sexual contact with others or practice safe sex to prevent spreading the infection (Mathew, Jr., 2021). 

People with asymptomatic herpes can still pass herpes on to others, just as those who experience outbreaks can.

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Current version

June 16, 2022

Written by

Amelia Willson

Fact checked by

Felix Gussone, MD

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About the medical reviewer

Felix Gussone, MD, Ro

Felix Gussone is a physician, health journalist and a Manager, Medical Content & Education at Ro.