Herpes is a common viral infection caused by the herpes simplex virus (HSV). It produces painful blisters or sores, most often around the mouth or genitals, and stays in the body permanently. Over 846 million people aged 15 to 49 are living with genital herpes worldwide, making it one of the most widespread infections on the planet.
Two Types of Herpes Simplex Virus
There are two closely related viruses. HSV-1 traditionally causes oral herpes, the cold sores that appear on or around the lips. HSV-2 primarily causes genital herpes. But these categories aren’t strict: HSV-1 can infect the genitals through oral sex, and HSV-2 can appear on the mouth, though that’s less common.
The numbers reflect how widespread both types are. According to 2020 WHO estimates, about 520 million people had genital HSV-2, while another 376 million had genital HSV-1. You can carry both types simultaneously, and roughly 50 million people do.
How Herpes Spreads
HSV-1 spreads primarily through kissing or oral sex. HSV-2 spreads through vaginal, anal, or oral sex. Both types transmit through direct skin-to-skin contact with an infected area, whether or not sores are visible at the time.
This is one of the most misunderstood aspects of herpes: you don’t need to see a sore to catch or pass it. The virus periodically reaches the skin surface without causing any visible symptoms, a process called asymptomatic shedding. Studies have found that people with genital HSV-2 shed the virus on roughly 3% of days even when no sores are present. That percentage may sound small, but over months and years, it creates real opportunities for transmission.
What Happens Inside the Body
After the initial infection, herpes does something that sets it apart from many other viruses: it hides. The virus travels along nerve fibers from the skin to clusters of nerve cells called sensory ganglia, located near the spine or at the base of the skull. Once there, the viral DNA settles into the cell nucleus and goes largely silent, producing almost no viral proteins. The immune system can’t detect or eliminate something that isn’t actively making itself known.
This is why herpes is a lifelong infection. The virus sits dormant in nerve cells indefinitely, occasionally reactivating and traveling back down the nerve fibers to the skin surface. Reactivation can produce a visible outbreak with sores, or it can be invisible, resulting in asymptomatic shedding. Triggers for reactivation vary from person to person but commonly include stress, illness, fatigue, sun exposure, and hormonal changes.
Symptoms of a First Outbreak
When someone is first infected, symptoms typically appear about 2 to 10 days after exposure. The first outbreak tends to be the most severe. It often starts with flu-like symptoms: fever, chills, muscle aches, fatigue, and nausea. Then small, fluid-filled blisters appear, usually grouped in clusters. The surrounding skin may be swollen and tender. If the sores are on the genitals, burning or stinging during urination is common.
A first outbreak typically lasts 2 to 4 weeks. During that time, the blisters break open, release fluid, gradually crust over, and heal without leaving scars.
Some people never notice their first infection at all. The symptoms can be mild enough to mistake for an ingrown hair, a yeast infection, or general skin irritation. Many people carry herpes for years without knowing it.
Recurrent Outbreaks
After the first episode, outbreaks tend to be shorter and less intense. Most recurrences heal within 3 to 7 days. There’s usually no fever or significant swelling the way there is the first time.
Many people experience a warning phase called a prodrome before sores appear. This feels like burning, itching, or tingling at or near the site of the original infection. Some people also notice aching in the lower back, buttocks, thighs, or knees. These sensations typically start a few hours before blisters develop, giving a window to begin treatment early.
The frequency of recurrences varies enormously. Some people have several outbreaks a year, especially in the first year or two after infection. Others have one and never have another. Over time, outbreaks generally become less frequent for most people regardless of treatment.
How Herpes Is Diagnosed
If you have an active sore, a healthcare provider can swab it and test for the virus directly. This is the most reliable way to get a diagnosis during an outbreak.
Blood tests detect antibodies your immune system produces in response to the virus. These tests can identify whether you carry HSV-1, HSV-2, or both, even when no sores are present. The catch is timing: after a new exposure, it can take up to 16 weeks or more for antibody levels to become detectable. Testing too soon after potential exposure can produce a false negative.
Treatment and Daily Management
There is no cure for herpes, but antiviral medications effectively reduce symptoms and transmission risk. Treatment falls into two main approaches.
Episodic therapy means taking antiviral medication at the first sign of an outbreak to shorten its duration and severity. This works best when started during the prodrome phase, before sores fully develop. A typical course lasts 1 to 5 days depending on the medication.
Suppressive therapy means taking a low dose of antiviral medication every day, whether or not you’re having symptoms. This approach reduces the frequency of outbreaks and also lowers the rate of asymptomatic shedding, which decreases the chance of passing the virus to a partner. Daily suppressive therapy is often recommended for people who experience frequent outbreaks (roughly six or more per year) or who want to reduce transmission risk in a sexual relationship.
Beyond medication, practical steps can help manage outbreaks. Keeping sores clean and dry speeds healing. Loose-fitting clothing reduces irritation around genital sores. Condoms and dental dams reduce (but don’t eliminate) transmission risk, since the virus can shed from skin not covered by a barrier.
Complications Worth Knowing About
For most healthy adults, herpes is more of an ongoing nuisance than a serious medical threat. But there are situations where the virus can cause significant harm.
Newborns are especially vulnerable. A mother with an active primary (first-time) herpes infection at delivery faces transmission rates as high as 60%. If the mother has a recurrent infection rather than a new one, the risk drops dramatically to less than 2%, because her existing antibodies provide some protection to the baby. Neonatal herpes can be severe, so pregnant women with herpes or partners who have herpes should discuss this with their care team well before delivery.
In rare cases, the virus can cause inflammation of the brain (encephalitis) or the membranes surrounding the brain and spinal cord (meningitis). People with weakened immune systems, such as those undergoing chemotherapy or living with advanced HIV, are at higher risk for more frequent and severe outbreaks and complications.
Living With Herpes
A herpes diagnosis often feels more emotionally difficult than it is medically. The stigma around herpes is disproportionate to its actual health impact for most people. Given that more than one in five adults worldwide carries a genital herpes infection, it is far more common than most people assume.
With antiviral treatment, awareness of prodrome symptoms, and open conversations with sexual partners, most people with herpes maintain normal sex lives and relationships. Outbreaks tend to become less frequent over the years, and many people eventually go long stretches without any symptoms at all.