Genital herpes spreads through direct skin-to-skin contact with an infected area, most often during vaginal, anal, or oral sex. The virus enters the body through mucosal surfaces (like the lining of the genitals or mouth) or through tiny cracks in the skin that may not be visible. Importantly, transmission can happen even when the infected person has no visible sores or symptoms.
How the Virus Passes Between People
Herpes simplex virus needs direct contact with skin or mucous membranes to spread. It cannot travel through the air, and it dies quickly on surfaces at room temperature or when it dries out. This means you won’t catch genital herpes from a toilet seat, towel, or hot tub. The virus requires the warmth and moisture of the human body to survive.
Two types of herpes simplex cause genital infections. HSV-2 is the more common cause and spreads primarily through genital-to-genital contact. HSV-1, traditionally associated with cold sores on the mouth, increasingly causes genital herpes through oral sex. When someone with an oral HSV-1 infection performs oral sex, the virus can establish a new infection on the recipient’s genitals. This route has become a significant source of new genital herpes cases.
Transmission Without Visible Symptoms
One of the most misunderstood aspects of genital herpes is that the virus sheds from the skin even when no sores, tingling, or other symptoms are present. This is called asymptomatic shedding, and it’s responsible for a large share of new infections. Many people who transmit herpes to a partner had no idea they were contagious at the time.
The virus lives in nerve cells near the base of the spine after the initial infection. Periodically, it reactivates and travels back to the skin surface, where it can be passed to another person through contact. This reactivation doesn’t always produce blisters or pain. Sometimes the virus is present on the skin in amounts large enough to infect someone else but too small to cause any noticeable symptoms in the person shedding it.
Where on the Body the Virus Sheds
Genital herpes doesn’t limit itself to one spot. Sores and viral shedding can occur on the penis, scrotum, vulva, vagina, buttocks, anus, or inner thighs. This matters for prevention because some of these areas aren’t covered by a condom. Skin-to-skin contact with any of these regions during sex can transmit the virus, even without penetration.
Actual Transmission Rates Between Partners
Not every sexual encounter with an infected person leads to transmission. Studies of heterosexual couples where one partner has genital HSV-2 found annual transmission rates of 11 to 17% when the infected partner was male and 3 to 4% when the infected partner was female. The difference likely reflects anatomy: the virus passes more easily from penile skin to the mucosal lining of the vagina than in the other direction.
These are annual rates without any protective measures. Combining strategies like condoms and daily antiviral medication brings those numbers down considerably.
What Reduces the Risk
Condoms provide meaningful but incomplete protection. A pooled analysis published in JAMA Internal Medicine found that consistent condom use (every time, not just sometimes) reduced the risk of acquiring HSV-2 by about 30%. That percentage applies equally to men and women. The reason condoms don’t offer higher protection is that the virus can shed from skin areas a condom doesn’t cover, like the upper thighs, buttocks, or base of the penis.
Daily suppressive antiviral therapy further lowers the risk. When the infected partner takes medication daily, it reduces viral shedding and cuts the chance of passing herpes to an uninfected partner. Combining daily antivirals with consistent condom use provides the strongest protection available for couples where one person carries the virus and the other doesn’t.
Avoiding sexual contact during active outbreaks is also important, since viral load is highest when sores are present. But given the role of asymptomatic shedding, skipping sex only during visible outbreaks isn’t enough on its own to prevent transmission.
Timeline After Exposure
If you’re exposed to the virus and become infected, the first symptoms typically appear within 2 to 10 days. A first outbreak usually involves a cluster of small blisters or open sores in the genital area that burn and can be quite painful. Some people also experience flu-like symptoms, swollen lymph nodes, or pain while urinating during this initial episode. Others never develop noticeable symptoms at all, which is one reason the virus spreads so widely. Roughly one in six people in the U.S. between ages 14 and 49 carries genital herpes.
Transmission During Pregnancy and Birth
Genital herpes can pass from mother to baby during vaginal delivery, and the risk depends heavily on timing. A first-time herpes infection acquired near the time of delivery is the most dangerous scenario, with transmission rates as high as 60%. The mother’s immune system hasn’t yet produced antibodies to the virus, so the baby has no passive protection.
When a mother has a recurrent infection (meaning she was infected well before pregnancy and her body has built up antibodies), the risk drops to less than 2%. Her antibodies cross the placenta and offer the baby significant protection, and viral shedding during a recurrence tends to be briefer and involve less virus than a first episode.
This is why the timing of a herpes diagnosis relative to pregnancy matters so much. A person with a long-standing infection who manages it with their care team faces a very different level of risk than someone who catches herpes for the first time in their third trimester.