Herpes is a sexually transmitted infection, but not exclusively. The answer depends on which type of herpes you’re talking about and where it shows up. HSV-2, the type most associated with genital herpes, is almost always sexually acquired. HSV-1, the type behind most cold sores, typically spreads through non-sexual contact in childhood, but it can also cause genital herpes when transmitted through oral sex.
Two Types, Two Different Patterns
Herpes simplex virus comes in two forms. HSV-1 mostly causes infections in or around the mouth. HSV-2 mostly causes infections in the genital and anal area. Both are capable of infecting either location, which is where the confusion starts.
HSV-2 spreads through sexual contact: vaginal, anal, or skin-to-skin genital contact with someone who carries the virus. Because nearly all HSV-2 infections are sexually acquired, the presence of HSV-2 antibodies in a blood test is considered strong evidence of a sexually transmitted infection. HSV-2 is, by almost any definition, an STI.
HSV-1 has a more complicated story. Most people with HSV-1 picked it up during childhood or young adulthood from non-sexual contact with saliva, like a kiss from a relative or sharing a cup. That’s not an STI. But HSV-1 can spread from the mouth to a partner’s genitals during oral sex, causing genital herpes. In that scenario, HSV-1 absolutely functions as an STI. An increasing proportion of new genital herpes cases are caused by HSV-1, especially among young women.
How Common Herpes Really Is
Around 846 million people between the ages of 15 and 49 are living with genital herpes worldwide, which works out to more than 1 in 5 adults in that age group. Of those, roughly 520 million have genital HSV-2 and about 376 million have genital HSV-1. Some 50 million people carry both types at the same time.
These numbers make genital herpes one of the most common infections on the planet, yet many people who have it don’t know. That’s largely because herpes often produces no visible symptoms or symptoms so mild they go unnoticed.
How Herpes Spreads (and Doesn’t)
You can get genital herpes through vaginal, anal, or oral sex. The virus transmits through contact with a herpes sore, saliva from someone with oral herpes, genital fluids, or simply skin in the genital or oral area of someone who carries the virus. Importantly, the skin doesn’t need to look abnormal for transmission to happen. HSV-2 is often transmitted when the infected person has no visible sores at all.
This is because of something called asymptomatic shedding: the virus periodically becomes active on the skin surface without producing any noticeable symptoms. For HSV-1, at least 70% of carriers shed the virus asymptomatically at least once a month, and many shed it more than six times per month. HSV-2 also sheds without symptoms from genital skin. Shedding episodes are typically brief, lasting one to three days, but they carry enough virus to infect a partner.
Herpes does not spread through toilet seats, bedding, swimming pools, towels, or silverware. It requires direct skin-to-skin or skin-to-mucous-membrane contact.
Why Most People Don’t Know They Have It
Many people with herpes never develop obvious blisters or sores, or they mistake mild symptoms for something else entirely, like an ingrown hair or a yeast infection. This is one reason the virus spreads so effectively: people who don’t know they’re infected can’t take precautions.
The CDC does not recommend routine herpes blood testing for people without symptoms. That might seem counterintuitive, but current blood tests have significant limitations. They can produce false positives, and for HSV-1, a positive blood test can’t distinguish between an oral infection (a cold sore you got as a kid) and a genital one. HSV-1 genital infections are confirmed by testing an actual sore or blister, not through blood work alone.
If you do have symptoms, a provider can often diagnose herpes visually or by swabbing an active sore. Blood tests are reserved for situations where there are no active lesions to test. After exposure, it can take up to 16 weeks or longer for antibodies to show up on a blood test, so timing matters.
Reducing Transmission Risk
Consistent condom use is the primary tool for reducing genital herpes transmission. In one large study, people who used condoms more than 75% of the time had roughly half the rate of HSV-2 infection compared to those who never used condoms (4.6% vs. 8%). Condoms aren’t perfect for herpes prevention because the virus can shed from skin that a condom doesn’t cover, but they meaningfully lower the risk.
Daily antiviral therapy is another option. People with recurrent genital herpes can take a daily antiviral medication that reduces both the frequency of outbreaks and the amount of asymptomatic shedding, which lowers the chance of passing the virus to a partner. This approach is commonly used by people in relationships where one partner has herpes and the other doesn’t.
Why the STI Label Matters
Classifying genital herpes as an STI isn’t just a technicality. It changes how you think about risk and prevention. If you’re sexually active, genital herpes is one of the most common infections you can encounter, and it can be transmitted even when your partner has no symptoms and doesn’t know they carry the virus.
HSV-2 infection also increases the risk of acquiring HIV by two to three times. The virus creates small breaks in mucosal tissue and triggers immune responses that make cells more vulnerable to HIV. For people living with both HSV-2 and HIV, herpes reactivations can increase HIV levels in genital secretions, potentially making HIV transmission more likely as well.
Genital herpes is a lifelong infection. There’s no cure, and recurrences vary widely from person to person. HSV-2 tends to recur more frequently and shed more often than genital HSV-1. Many people find that outbreaks become less frequent over the years, and antiviral medication can shorten and reduce episodes when they do occur.