Herpes spreads primarily through direct skin-to-skin contact with someone who has the virus, even when no sores are visible. The two types, HSV-1 and HSV-2, each have preferred routes of transmission, but both can infect the mouth or genitals depending on the type of contact involved.
Sexual Contact Is the Main Route
Vaginal, anal, and oral sex are the most common ways herpes passes between people. You can get herpes through contact with a partner’s sores, saliva, genital fluids, or simply the skin around their mouth or genitals. The virus enters the body through mucous membranes (the moist lining of the mouth, genitals, and rectum) or through tiny breaks in the skin that you may not even notice.
HSV-1 is traditionally associated with oral herpes (cold sores), but it increasingly causes genital infections too, transmitted when someone with oral HSV-1 performs oral sex on a partner. HSV-2 spreads mainly through genital or anal contact and rarely infects the mouth.
Transmission Without Visible Sores
One of the most important things to understand about herpes is that the virus can shed from skin that looks completely normal. This is called asymptomatic shedding, and it accounts for a significant share of new infections. The person spreading the virus often has no idea they’re doing so.
HSV-2 sheds frequently. In the first year of infection, people with genital HSV-2 shed the virus on roughly 34% of days. Even a decade later, shedding still occurs on about 17% of days. HSV-1 in the genital area sheds less often: around 12% of days at two months after infection, dropping to about 7% by eleven months, and falling further over time. In most cases during a University of Washington study, participants who were shedding virus had no symptoms at the time.
Who Passes It to Whom
In couples where one partner has genital HSV-2 and the other doesn’t, transmission rates differ by gender. In one study that followed discordant couples for about a year, roughly 17% of female partners caught the virus from an infected male partner, while only about 4% of male partners caught it from an infected female partner. The difference likely relates to the larger area of mucous membrane exposed during sex for women.
Oral-to-Genital Spread
Cold sores aren’t just an oral problem. If you have HSV-1 on or around your mouth, you can transmit it to a partner’s genitals through oral sex, giving them genital herpes. This is now one of the leading causes of new genital herpes cases in young adults. The reverse is less common: HSV-2 from the genitals rarely establishes itself in the mouth.
The risk is highest when a cold sore is actively present, but oral HSV-1 can also shed without any visible sore, meaning transmission is possible even when the mouth looks and feels fine.
Transmission During Pregnancy and Birth
A mother with herpes can pass the virus to her baby during vaginal delivery. The risk depends heavily on timing. If the mother catches herpes for the first time near the end of pregnancy, the transmission risk is highest, up to 60%, because her body hasn’t yet built antibodies to pass along to the baby. If she already had a different type of herpes before (providing some cross-reactive antibodies), the risk drops to around 30%. For mothers with a long-standing, recurrent infection, the risk to the newborn is less than 2%, because type-specific antibodies are already present and shared with the baby.
Spreading It to Another Part of Your Own Body
After your initial infection, autoinoculation (transferring the virus from one body part to another on yourself) is very unlikely. Your immune system produces antibodies after the first infection that circulate in your blood for years and generally prevent the virus from establishing a new infection at a different site. The virus stays dormant in the nerve that supplies the area where it first entered. Reactivations tend to happen in the same spot or at least along the same nerve pathway, which is why someone with a history of cold sores on the lip might occasionally get a flare-up near the eye, since both areas share the same nerve supply.
Toilet Seats, Towels, and Other Objects
Herpes dies quickly outside the body. The Mayo Clinic describes it as “nearly impossible” to catch genital herpes from a toilet seat, towel, or other shared object. The virus requires direct person-to-person contact, almost always involving skin or mucous membranes, to successfully infect a new host.
How Condoms and Antivirals Reduce Risk
Condoms lower the risk of herpes transmission, but not equally for everyone. Research tracking couples over time found that consistent condom use reduced a woman’s risk of acquiring HSV-2 by about 90%, but did not show a statistically significant protective effect for men. This is likely because condoms cover the primary site of viral shedding in men but don’t fully cover the broader genital skin area in women where shedding can occur, which men contact during sex.
Daily suppressive antiviral therapy taken by the infected partner also reduces transmission. The CDC notes that daily use of valacyclovir decreases HSV-2 transmission in discordant heterosexual couples. Combining daily antivirals with consistent condom use offers the greatest risk reduction available outside of abstaining from contact during outbreaks.
Avoiding sexual contact during active outbreaks, when sores, tingling, or burning are present, is one of the simplest and most effective precautions. The risk of transmission is highest when sores are visible, even though the virus can spread at other times too.