Genital herpes spreads through skin-to-skin contact during vaginal, anal, or oral sex with someone who carries the virus. More than 1 in 5 adults worldwide between ages 15 and 49 have a genital herpes infection, and many of them don’t know it, because the virus frequently passes from person to person without any visible symptoms.
The Two Types of Herpes That Cause It
Two related viruses cause genital herpes: HSV-1 and HSV-2. HSV-2 is the one most people associate with genital herpes. It spreads during sex through contact with genital or anal skin, sores, or fluids of an infected person. Globally, about 520 million people aged 15 to 49 were living with genital HSV-2 as of 2020.
HSV-1, the virus behind most cold sores, is increasingly responsible for genital infections too. An estimated 376 million people have genital HSV-1. The most common way this happens is receiving oral sex from someone who carries HSV-1 in or around their mouth. That person may never have had a visible cold sore and may not realize they carry the virus at all. You can have both types at the same time.
Transmission Without Visible Symptoms
This is the part that surprises most people: herpes often spreads when no sores are present. HSV-2 can be transmitted even when the skin looks completely normal, and the WHO notes it is “often transmitted in the absence of symptoms.” This happens through a process called viral shedding, where the virus periodically becomes active on the skin surface without producing blisters or any sensation the carrier would notice.
How often shedding occurs varies enormously from person to person. Studies using sensitive DNA detection methods have found the virus present on the skin anywhere from zero to 92% of days tested, depending on the individual. On any single day, older lab methods detected the virus about 6% of the time, while more sensitive tests picked it up far more frequently. This variability helps explain why some couples go years without transmission while others pass the virus early in a relationship.
Specific Ways the Virus Spreads
You can get genital herpes through contact with any of the following from an infected partner:
- A herpes sore on the genitals, anus, or mouth
- Genital fluids from a partner with a genital infection
- Saliva from a partner with an oral herpes infection (during oral sex)
- Skin in the genital or oral area that is shedding the virus without visible sores
The virus enters the body through mucous membranes (the moist lining of the mouth, genitals, or rectum) or through tiny breaks in the skin. These entry points are why genital, anal, and oral sex all carry risk. Herpes can also cause sores or small breaks in these tissues, which in turn makes a person more vulnerable to other sexually transmitted infections.
Ways You Cannot Get It
Herpes dies quickly outside the human body. It is nearly impossible to get genital herpes from a toilet seat, a shared towel, or any other surface. The Mayo Clinic is direct on this point: the virus simply doesn’t survive long enough on objects to remain infectious. Casual contact like hugging, shaking hands, or sharing food does not spread genital herpes either.
If you already have herpes in one location, the chance of spreading it to another part of your own body (called autoinoculation) is very low after the initial infection. Your immune system produces antibodies that circulate for years, preventing a new primary infection at a different site. When the virus does reactivate, it typically reappears in the same area or nearby, because it lives in the nerve that supplies that region of skin.
Why Condoms Help but Don’t Eliminate Risk
Consistent condom use roughly cuts the risk of acquiring HSV-2 in half. One large study found that 8% of participants who never used condoms acquired HSV-2 during the study period, compared to 4.6% of those who used condoms more than 75% of the time. The more consistently condoms were used, the lower the transmission rate.
Condoms can’t eliminate the risk entirely because herpes sores and viral shedding can occur on skin that a condom doesn’t cover, including the upper thighs, buttocks, and areas around the genitals. For couples where one partner has genital herpes and the other doesn’t, daily antiviral medication taken by the infected partner further reduces the chance of transmission. The combination of condoms plus daily antivirals provides the strongest protection outside of abstaining from sexual contact during outbreaks.
Passing Herpes to a Baby During Birth
In about 85% of neonatal herpes cases, the virus passes from mother to baby during delivery. The risk depends heavily on timing. If you contract genital herpes for the first time during pregnancy, especially in the second half, the risk to your baby is highest because your body hasn’t yet built up antibodies to share through the placenta.
If you had genital herpes before becoming pregnant, the risk is much lower. Your existing antibodies cross the placenta and offer the baby protection. The virus would need to reactivate during delivery to pose a threat, and even then, a recurrent infection is far less likely to cause neonatal herpes than a brand-new one. This is why providers ask about herpes history during pregnancy, so they can plan delivery and, if needed, prescribe antiviral medication in the final weeks.
Why So Many People Don’t Know They Have It
Most people with genital herpes have mild symptoms or none at all. Many carriers were never diagnosed and have no idea they’re infectious. This is the single biggest reason the virus continues to spread so effectively: a partner who genuinely believes they’re “clean” can still transmit herpes on any given day through invisible viral shedding. Standard STI panels don’t always include herpes testing unless you specifically request it or have symptoms, which means a negative STI screen doesn’t necessarily mean someone is herpes-free.
If you’re concerned about exposure, a type-specific blood test can detect antibodies to HSV-1 and HSV-2 separately. These antibodies take a few weeks to develop after infection, so testing too early after a possible exposure can produce a false negative. If you develop sores, a swab test of the sore itself is more accurate and can confirm which type of herpes is present.