HSV-2 is a strain of the herpes simplex virus that causes genital herpes. It’s one of the most common sexually transmitted infections in the world, affecting roughly 520 million people between the ages of 15 and 49. Once you’re infected, the virus stays in your body permanently, going dormant in nerve clusters near the base of your spine and periodically reactivating to cause outbreaks of painful sores.
How HSV-2 Infects the Body
HSV-2 spreads through sexual contact with someone who has the virus. After entering through the skin or mucous membranes of the genitals, it travels along nerve fibers to clusters of nerve cells called ganglia in the lower spine. There, it essentially goes to sleep, producing only a small set of genetic transcripts that keep it hidden from the immune system.
This dormant state is what makes herpes a lifelong infection. The virus isn’t actively multiplying, so the immune system can’t clear it. Periodically, something triggers reactivation: the virus travels back down the nerve fibers to the skin’s surface, where it either causes visible sores or sheds silently without symptoms. On average, people with HSV-2 shed the virus on about 18% of days, and roughly 80% of that shedding happens without any noticeable symptoms. This is why most transmissions happen when the infected person doesn’t know they’re contagious.
How Many People Have It
According to World Health Organization estimates from 2020, about 520 million people aged 15 to 49 worldwide are living with genital HSV-2. That’s more than 1 in 5 adults globally when combined with genital infections caused by the closely related HSV-1. It’s possible to carry both types simultaneously.
What a First Outbreak Feels Like
A primary HSV-2 infection is typically the most severe episode you’ll experience. It begins with small red spots or bumps on the genitals that progress into fluid-filled blisters, then open into painful ulcers before crusting over and healing. The entire process takes about 19 days on average, regardless of treatment.
The sores can be intensely painful, particularly in women, where vulvar swelling and burning during urination are common. Swollen, tender lymph nodes in the groin often accompany the outbreak. Up to 24% of people with a primary infection also develop systemic symptoms like fever, headache, and general fatigue from the virus briefly entering the bloodstream. Not everyone with a primary infection gets a dramatic outbreak, though. Some people have symptoms so mild they mistake them for something else entirely, or they have no noticeable symptoms at all.
Recurrent Outbreaks
After the first episode, outbreaks tend to be shorter, less painful, and less frequent over time. Many people notice a prodrome, a tingling, burning, or aching sensation at the site, hours to days before blisters appear. Recurrent outbreaks in the genital area happen roughly 0.33 times per month for HSV-2, which works out to about four episodes per year on average, though this varies widely from person to person. Some people have monthly recurrences while others go years between outbreaks.
Starting antiviral treatment within the first day of symptoms or during the prodrome phase makes the biggest difference in shortening a recurrence. If healing isn’t complete after 10 days, treatment can be extended.
HSV-2 vs. HSV-1
Both viruses are closely related and cause similar-looking sores, but they behave differently depending on where they set up their dormant infection. HSV-1 prefers the nerve clusters near the face and recurs most frequently as oral cold sores. HSV-2 prefers the nerve clusters near the base of the spine and recurs most frequently in the genital area.
The numbers make this clear. In one study tracking recurrence patterns, genital HSV-2 infections recurred at a rate of 0.33 per month, while genital HSV-1 infections recurred at just 0.02 per month. Going the other direction, oral HSV-2 infections barely recurred at all (0.001 per month). Each virus is essentially tuned to reactivate efficiently in its preferred location, which is driven by the specific types of nerve cells each virus targets for latency.
How HSV-2 Spreads
HSV-2 transmits through genital-to-genital or genital-to-oral contact during sex. The virus passes from skin that is shedding the virus to a partner’s mucous membranes or broken skin. Because most shedding is asymptomatic, waiting for visible sores to appear before taking precautions isn’t a reliable prevention strategy.
Consistent condom use significantly reduces transmission risk, but the degree of protection depends on the direction of transmission. Condoms reduce per-act transmission risk from men to women by about 96%, which is substantial protection. For transmission from women to men, the reduction is about 65%, likely because the virus can shed from areas a condom doesn’t cover. Daily suppressive antiviral therapy further reduces the risk of passing the virus to a partner.
Testing and Diagnosis
If you have active sores, a healthcare provider can swab them directly to test for the virus. This is the most reliable method during an outbreak. When no sores are present, a blood test that looks for HSV-2-specific antibodies (IgG) can detect a past infection, but these tests have important limitations.
After exposure, it can take up to 16 weeks or more for antibodies to reach detectable levels, so testing too early can produce a false negative. False positives are also more common with herpes blood tests than with tests for infections like chlamydia or gonorrhea. Because of these accuracy issues, routine herpes screening isn’t recommended for people without symptoms. Testing is most useful when you have symptoms, a known exposure, or a partner with herpes.
How HSV-2 Is Managed
There’s no cure for HSV-2, but antiviral medications effectively shorten outbreaks and reduce how often they happen. Two approaches exist: episodic therapy, where you take medication at the first sign of an outbreak to speed healing, and suppressive therapy, where you take a daily antiviral to prevent outbreaks from occurring in the first place. Suppressive therapy also lowers the amount of virus you shed, reducing the risk of transmitting to a partner.
For people with infrequent or mild outbreaks, episodic therapy may be enough. Those with frequent recurrences or who want to minimize transmission risk to a partner often benefit from daily suppressive therapy. Both approaches use the same class of antiviral drugs, and side effects are generally mild.
Risks During Pregnancy
The most serious complication of HSV-2 is neonatal herpes, which occurs when the virus passes to a baby during delivery. The risk depends heavily on timing. A woman who acquires a new HSV-2 infection during pregnancy, particularly near the time of delivery, has roughly a 50% chance of transmitting the virus to her newborn. For women with a recurrent infection (meaning they were infected before pregnancy), the risk drops to less than 3%, because the mother’s immune system has had time to produce antibodies that partially protect the baby.
Neonatal herpes can be severe, so women with known HSV-2 are typically placed on suppressive antiviral therapy in the final weeks of pregnancy. If active lesions are present at the time of labor, delivery by cesarean section is recommended to avoid exposing the baby to the virus.
Rare but Serious Complications
In most people, HSV-2 remains a skin-level infection that causes periodic discomfort but no lasting damage. In rare cases, the virus can cause meningitis, an inflammation of the membranes surrounding the brain and spinal cord, marked by severe headache, sensitivity to light, fever, and neck stiffness. HSV-2 meningitis typically resolves on its own but can recur. Even more rarely, disseminated infection can affect the liver, which is a particular concern for pregnant women who may develop fever and severely elevated liver enzymes without any visible genital sores.