Yes, herpes is classified as a sexually transmitted infection (STI). The CDC categorizes genital herpes, caused by herpes simplex virus type 1 (HSV-1) or type 2 (HSV-2), as a common STI. But the full picture is more nuanced than that label suggests, because the same viruses also spread through non-sexual contact, and most people who carry herpes don’t know they have it.
Two Viruses, Different Reputations
HSV-1 and HSV-2 are closely related but behave differently. HSV-1 mostly spreads through oral contact and causes cold sores around the mouth. HSV-2 spreads primarily through sexual contact and is the classic cause of genital herpes. Both are lifelong infections with no cure.
Here’s where the STI label gets complicated: HSV-1 increasingly causes genital herpes too. Research tracking genital herpes cases over a six-year period found that by 1999, HSV-1 was responsible for nearly 42% of all genital herpes cases, with rates as high as 45% in women. This means a virus most people think of as “just cold sores” is now responsible for a large share of genital infections, typically transmitted through oral sex.
So while HSV-2 is almost always sexually transmitted, HSV-1 can be either an STI or a non-sexual infection depending on where and how it’s passed. A child who gets a cold sore from a parent’s kiss has the same virus as someone who contracts genital HSV-1 from a partner.
How Herpes Spreads
Herpes transmits through direct skin-to-skin contact with an infected area. For genital herpes, this means vaginal, anal, or oral sex. For oral herpes, it can be as simple as kissing or sharing utensils. The virus doesn’t survive well on surfaces, so transmission from towels or toilet seats is not a realistic concern.
What makes herpes particularly easy to spread is something called viral shedding. The virus periodically reactivates and reaches the skin surface even when no sores are visible. People with HSV-2 shed the virus on roughly 18% of days, and about 80% of that shedding happens without any symptoms at all. Most herpes transmissions happen during these invisible episodes, not during obvious outbreaks.
How Common Herpes Really Is
Herpes is one of the most widespread infections on the planet. The World Health Organization estimates that the majority of the global population carries HSV-1, with most people infected during childhood. HSV-2 is less common but still affects hundreds of millions of people worldwide. Many carriers never develop noticeable symptoms, which is a major reason the virus continues to spread so effectively.
Testing Is Less Straightforward Than You’d Expect
Unlike chlamydia or gonorrhea, herpes is not part of standard STI screening panels. The most reliable way to diagnose herpes is by swabbing an active blister or sore that hasn’t started healing yet. Blood tests exist but have significant limitations. After exposure, it can take up to 16 weeks or more for antibody-based blood tests to detect the infection, meaning a negative result shortly after exposure may not be accurate.
If you have visible sores, getting them swabbed while they’re fresh gives the most definitive answer. If you have no symptoms but want to know your status, a blood test can detect antibodies to HSV-1 and HSV-2 separately, though the timing and accuracy limitations are worth discussing with a provider.
What Outbreaks Feel Like
A first genital herpes outbreak is usually the worst. It can involve painful blisters or open sores in the genital area, along with flu-like symptoms such as fever, body aches, and swollen lymph nodes. The sores crust over and heal, typically within two to four weeks.
Recurrent outbreaks tend to be milder and shorter. Some people have several outbreaks a year, while others go years between episodes or never have a noticeable one at all. Over time, outbreaks generally become less frequent as the immune system gets better at keeping the virus in check.
Treatment Options
Antiviral medications can’t eliminate herpes, but they significantly reduce the severity and frequency of outbreaks. There are two main approaches. Episodic therapy means taking antivirals for a few days when you feel an outbreak coming on, which shortens its duration. Suppressive therapy means taking a daily antiviral pill to prevent outbreaks from happening in the first place and to reduce the risk of transmitting the virus to a partner.
Suppressive therapy is particularly useful for people who experience frequent outbreaks (more than a few per year) or who want to lower the chance of passing herpes to a sexual partner. Many people take daily antivirals for years without significant side effects.
How Condoms and Other Measures Reduce Risk
Condoms provide meaningful protection, though the degree varies. Research on couples where one partner had HSV-2 found that consistent condom use reduced per-act transmission risk by 96% from men to women and 65% from women to men. The difference likely reflects the fact that condoms cover more of the skin area involved in male-to-female transmission than the reverse.
Combining condoms with daily suppressive antiviral therapy offers the strongest protection for discordant couples (where one partner has herpes and the other doesn’t). Avoiding sexual contact during visible outbreaks further reduces risk, though it doesn’t eliminate it entirely because of asymptomatic shedding.
Herpes During Pregnancy
The biggest concern with herpes in pregnancy is transmission to the baby during delivery. The risk varies dramatically depending on timing. A woman who contracts genital herpes for the first time near the end of pregnancy faces a transmission risk as high as 57%, because her body hasn’t yet built antibodies that could partially protect the baby. For women with recurrent herpes (meaning they were infected before pregnancy), the risk drops to about 2%. This is why providers pay close attention to herpes status in the final weeks of pregnancy and may recommend antiviral therapy or cesarean delivery when active lesions are present.