Herpes simplex virus spreads through direct skin-to-skin contact with an infected person, even when they have no visible sores. There are two types: HSV-1, which typically causes oral herpes (cold sores), and HSV-2, which typically causes genital herpes. Both are extraordinarily common. Over 846 million people between the ages of 15 and 49 have a genital herpes infection worldwide, and an estimated 42 million people acquire a new genital infection every year.
Skin Contact Is the Primary Route
HSV doesn’t travel through the air or spread easily from contaminated surfaces. It requires direct contact with infected skin, sores, saliva, or genital fluids. HSV-1 spreads mainly through contact with the virus in sores, saliva, or skin around the mouth. Kissing is the most common route. HSV-2 spreads mainly during sex through contact with genital or anal skin, sores, or fluids from someone carrying the virus.
What makes herpes especially easy to transmit is that you don’t need to touch an active sore. The virus periodically “sheds” from the skin surface without causing any visible symptoms. In one study, 70% of new transmissions happened during these asymptomatic shedding periods, when the infected person had no idea they were contagious. Many people who pass the virus to a partner don’t know they carry it themselves.
Oral Sex Can Spread HSV-1 to the Genitals
HSV-1 was once thought of as strictly an “above the waist” virus, but that’s no longer accurate. Oral herpes caused by HSV-1 can spread from the mouth to the genitals through oral sex. This has become an increasingly recognized cause of genital herpes, particularly in younger adults. You can get genital herpes if you receive oral sex from a partner who has oral herpes, even if they haven’t had a cold sore in months.
The reverse is also possible. Contact with genital herpes sores or skin during oral sex can lead to an oral HSV-2 infection, though this is less common. The key point is that both virus types can infect either location, and oral sex is a significant transmission route that many people overlook.
What Counts as “Contact”
The CDC lists several specific contact scenarios that can transmit herpes:
- Touching a herpes sore on a partner’s mouth, genitals, or anus
- Saliva from a partner with oral herpes, even through kissing
- Genital fluids from a partner with genital herpes
- Skin in the oral area of a partner with oral herpes, even without a visible sore
- Skin in the genital area of a partner with genital herpes, even without a visible sore
Vaginal, anal, and oral sex all carry transmission risk. The virus enters through mucous membranes (the thin, moist tissue lining the mouth, genitals, and anus) or through tiny breaks in the skin that you can’t see or feel.
Can You Get It From Objects or Surfaces?
HSV can survive on dry surfaces for anywhere from a few hours to several weeks, with longer survival at lower humidity. However, direct contact with infected skin or secretions remains the overwhelmingly dominant way people contract the virus. Surface transmission is theoretically possible but not considered a meaningful risk in real-world conditions. You’re unlikely to catch herpes from a toilet seat, a towel, or a shared drink, though sharing items that contact active sores (like a lip balm during a cold sore outbreak) is worth avoiding.
Transmission During Childbirth
In rare cases, a mother can pass HSV to her baby during vaginal delivery. This is most likely when the mother has an active genital herpes outbreak at the time of labor, especially visible sores. The risk is highest when a woman contracts genital herpes for the first time late in pregnancy, because her body hasn’t yet built up antibodies that would partially protect the baby.
Some women carry the virus without knowing it and may have internal sores they can’t see. For pregnant women with an active outbreak or a new infection acquired in the third trimester, a cesarean delivery is typically recommended to reduce the baby’s exposure. Neonatal herpes is serious but uncommon, affecting a small fraction of births even among women who carry HSV.
How Quickly Symptoms Appear
After exposure, the incubation period is usually 2 to 12 days before any symptoms show up. The first outbreak tends to be the most noticeable, often involving painful blisters or sores at the site of infection, along with flu-like symptoms such as fever, body aches, and swollen glands. Some people experience a mild first episode they barely notice or attribute to something else entirely. Many people never develop recognizable symptoms at all, which is a major reason the virus spreads so effectively.
How Much Do Condoms Help?
Condoms reduce the risk of herpes transmission but don’t eliminate it. Because herpes can shed from skin that a condom doesn’t cover (the base of the penis, the upper thighs, the vulva), barrier protection is imperfect for this particular virus. One study found that 8% of people who never used condoms acquired HSV-2, compared with 4.6% of those who used condoms more than 75% of the time. That’s roughly a 40% reduction in risk with consistent use.
Avoiding sexual contact during active outbreaks further lowers the odds of transmission, since viral shedding is highest when sores are present. Antiviral medications taken daily by the infected partner also reduce shedding and cut transmission risk significantly. The combination of condoms, antivirals, and avoiding contact during outbreaks provides the strongest protection, though none of these measures alone or together can guarantee prevention.
Why So Many People Carry It Without Knowing
More than 200 million people aged 15 to 49 experienced at least one symptomatic episode in 2020, but that’s only a fraction of the total number infected. The majority of people with HSV never get noticeable symptoms or get symptoms so mild they don’t recognize them as herpes. Standard STI panels often don’t include herpes testing unless you specifically request it or have symptoms, which means many carriers go undiagnosed for years or even a lifetime. This is the core reason herpes is so widespread: most transmission comes from people who don’t know they have it, during periods when the virus sheds invisibly from their skin.