Herpes is a common viral infection caused by the herpes simplex virus (HSV) that produces sores on the mouth, genitals, or both. Over 846 million people between the ages of 15 and 49 have a genital herpes infection worldwide, making it one of the most prevalent sexually transmitted infections on the planet. The virus comes in two types, persists for life in the nervous system, and can be transmitted even when no symptoms are visible.
HSV-1 vs. HSV-2
There are two types of herpes simplex virus. HSV-1 is more commonly linked to oral herpes (cold sores around the mouth), while HSV-2 is more often associated with genital herpes. But either type can infect either location. If a partner with oral HSV-1 performs oral sex, they can transmit the virus to the other person’s genitals. Likewise, a partner with genital HSV-2 can transmit the virus to someone’s mouth through oral sex.
The distinction matters beyond just location. Genital infections caused by HSV-1 tend to produce fewer recurring outbreaks than genital infections caused by HSV-2. It’s also possible to carry both types simultaneously. Globally, about 520 million people had genital HSV-2 in 2020, and another 376 million had genital HSV-1, with roughly 50 million carrying both.
How the Virus Stays in Your Body
What makes herpes different from many other infections is that it never leaves. During the initial infection, the virus replicates in skin or mucous membrane cells and then enters nearby nerve endings. From there, it travels along the nerve fibers to clusters of nerve cells deeper in the body. Oral herpes typically settles into the nerve cluster that serves the face, while genital herpes reaches the nerve network in the pelvis.
Once inside those nerve cells, the virus essentially goes quiet. It shuts down all of its active genes and sits in a dormant state, invisible to the immune system. This is why herpes can’t be cured: the dormant virus is physically tucked away inside neurons where antiviral drugs and immune cells can’t eliminate it.
Periodically, the virus wakes up. It travels back along the nerve fibers to the skin surface, where it can cause a new outbreak of sores or shed silently without any visible symptoms. Known triggers for reactivation include UV light exposure (like a sunburn on the lips), emotional stress, fever, illness that suppresses the immune system, and physical trauma to the affected skin.
What an Outbreak Feels Like
A first herpes outbreak is usually the worst. Many people experience a prodrome phase: a tingling, itching, or burning sensation in the area where sores are about to appear. This is the virus traveling back to the skin surface. Within a day or two, small fluid-filled blisters form, either on the lips and around the mouth (oral herpes) or on the genitals, buttocks, or thighs (genital herpes). The blisters break open into shallow, painful ulcers that eventually crust over and heal.
A primary outbreak can also come with systemic symptoms that feel like the flu: fever, body aches, swollen lymph nodes, and fatigue. The whole episode typically lasts two to four weeks for a first occurrence. Recurrent outbreaks are usually shorter, milder, and less frequent over time. Some people have multiple recurrences per year, especially in the first year or two after infection, while others rarely or never have a noticeable outbreak again.
A significant number of people with herpes never realize they have it. Their outbreaks are so mild they get mistaken for ingrown hairs, razor burn, or a minor skin irritation, or they never have visible symptoms at all.
Transmission Without Symptoms
One of the most important things to understand about herpes is that it spreads primarily through skin-to-skin contact, and it doesn’t require a visible sore to be contagious. Research has found that roughly 70% of herpes transmissions happen during periods of asymptomatic viral shedding, when the virus is actively present on the skin but no sores or symptoms are visible.
Asymptomatic shedding is more frequent in the period soon after someone first acquires the virus and is generally more common with genital HSV-2 than with other types. Over time, shedding episodes tend to become less frequent, but they never stop entirely. This is why many people who transmit the virus to a partner genuinely didn’t know they were infectious at the time.
How Herpes Is Diagnosed
If you have an active sore, the most reliable test is a PCR swab, which detects the virus’s genetic material directly from the lesion. PCR testing picks up herpes with about 86% sensitivity and essentially zero false positives, making it far more accurate than the older method of viral culture, which catches only about 43% of true positives. Viral culture works best when blisters are fresh and fluid-filled; by the time a sore has started crusting over, the culture often comes back negative even when herpes is present.
For people without active sores, a blood test can detect antibodies to HSV-1 or HSV-2, indicating a past infection. Blood tests can distinguish between the two types, but they can’t tell you where on the body the infection is located, and they may not turn positive until several weeks after initial infection while the immune system builds its response.
Treatment and Outbreak Management
Antiviral medications don’t cure herpes, but they can shorten outbreaks, reduce their severity, and lower the risk of passing the virus to a partner. The most commonly prescribed antivirals work by blocking the virus’s ability to replicate once it reactivates.
There are two main approaches to treatment. Episodic therapy means taking medication at the first sign of an outbreak (ideally during the tingling prodrome phase) for a short course of one to five days, depending on the specific regimen. This can shorten an outbreak by a day or two and reduce the severity of symptoms. Suppressive therapy means taking a lower dose of antiviral medication every day, regardless of whether you’re having an outbreak. Daily suppressive therapy reduces the frequency of outbreaks and also decreases the amount of asymptomatic viral shedding, which lowers the chance of transmitting the virus to a sexual partner.
Your doctor can help determine which approach makes more sense based on how often you experience outbreaks and whether reducing transmission risk to a partner is a priority.
Reducing Transmission Risk
Consistent condom use reduces the risk of acquiring genital HSV-2 by about 30% compared to never using condoms. That number is lower than many people expect, and the reason is straightforward: condoms only cover the shaft of the penis, while herpes can affect surrounding skin on the thighs, buttocks, and areas not covered by a condom. Still, 30% risk reduction is meaningful, especially when combined with other strategies.
Layering prevention methods improves the odds. Daily suppressive antiviral therapy significantly reduces both outbreaks and viral shedding. Avoiding sexual contact during active outbreaks and prodrome symptoms (the tingling or burning that signals a sore is coming) removes the highest-risk encounters. No single method eliminates risk entirely, but combining antivirals, condoms, and outbreak awareness substantially lowers it.
Herpes During Pregnancy
Herpes can pose a serious risk to newborns, though transmission from mother to child is uncommon with proper management. About 85% of neonatal herpes cases result from exposure during delivery, with the remainder occurring before or after birth.
The risk varies dramatically depending on when the mother acquired herpes. A new genital herpes infection near the time of delivery carries a transmission risk as high as 57%, because the mother’s immune system hasn’t yet produced protective antibodies that cross the placenta to the baby. A recurrent outbreak in a mother with a long-standing infection carries only about a 2% risk, thanks to those existing antibodies.
Women with a history of genital herpes are typically offered daily antiviral therapy starting at 36 weeks of pregnancy to suppress outbreaks near the delivery date. If active genital lesions or prodromal symptoms are present when labor begins, a cesarean delivery is recommended to avoid exposing the baby to the virus in the birth canal. Women with a herpes history but no active lesions at the time of delivery can deliver vaginally.