Herpes Simplex Virus 1 vs. Herpes Simplex Virus 2—Understanding the Difference

Herpes simplex virus (HSV) is a common—and one of the most confusing—infections. Two types exist: herpes simplex virus 1 (HSV-1) and herpes simplex virus 2 (HSV-2). Both can affect your genitals or the area around and in your mouth. However, HSV-1 usually causes blisters on or around the lips, while HSV-2 primarily affects the genitals.

Learn more about the two types of herpes, including how to tell them apart, symptoms, transmission, and treatment.

Types of Herpes: HSV 1 vs. HSV 2 

"HSV-1 and HSV-2 are two different viruses. They're related, but they don't morph into one another," Anna Wald, MD, a spokesperson for the Infectious Diseases Society of America and head of the Division of Allergy and Infectious Diseases at the University of Washington, told Health. "'Oral' and 'genital' refer to the site of the infection. Either virus can infect either site."

HSV-1 most commonly causes oral herpes, sometimes called cold sores or fever blisters, on your lips, mouth, and throat. Most people with oral herpes picked it up as a child, maybe from a kiss or from passing toys from mouth to mouth in daycare. Over half of Americans have been exposed to HSV-1.

HSV-2 can also cause oral herpes, but it's less common. HSV-2 is transmitted primarily through genital contact. It is the leading cause of genital herpes, a sexually transmitted infection (STI) that can occur on the vagina, vulva, cervix, anus, penis, scrotum, butt, or inner thighs. Approximately 1 in 6 people have HSV-2.

While HSV-2 primarily causes genital infections, HSV-1 can cause them, too, primarily through oral sex. HSV-1 causes up to about half of all new genital herpes cases, H. Hunter Handsfield, MD, a spokesperson for the American Sexual Health Association and professor emeritus of medicine at the Center for AIDS and STD at the University of Washington, told Health.

Symptoms of HSV-2 vs. HSV-1

What many people don't know is that herpes often has no symptoms at all. Most people with either infection don't know that they have it or that they likely got it from someone who didn't know they had it, either, Dr. Wald said.

If a person does experience symptoms, they tend to come and go. Genital herpes recurrences are more frequent with HSV-2 than with HSV-1. But the virus itself lingers. "The virus goes latent but is never totally eradicated by the immune system," Dr. Handsfield said. It's estimated that of individuals between the ages of 14 to 49 years old infected with HSV-2, 87.4% don't know they have it.

Genital herpes symptoms may include genital sores (small red bumps or white blisters), ulcers, and scabbing. The initial outbreak is often accompanied by fever, swollen lymph nodes in your groin, a headache, and muscle aches.

"It can be very painful," Dr. Handsfield said. Oral herpes symptoms include fluid-filled sores on the lips, inside the mouth, and on the back of the throat. Lymph nodes in the neck might swell, too.

Both viruses can spread regardless of whether there are known symptoms. "That's what's really frustrating," Dr. Wald said. "It's unpredictable."

Which Type of Herpes Do I Have?

It's not always easy to tell if someone has HSV-1 or HSV-2. "The ideal way to know that it's herpes and which type it is, is to test at the time [lesions] are active with PCR testing," Dr. Handsfield said. Nucleic acid amplification tests like polymerase chain reaction (PCR) testing are done and can involve collecting cells or fluid from an active herpes infection, meaning herpes sores or lesions are present.

Blood tests can be less reliable, but they may be helpful if PCR testing is negative or if a person doesn't have an active outbreak at the time of testing, Dr. Handsfield said.

Once you are diagnosed, you can take steps toward prevention and treatment.

How To Avoid Transmission

While there's no cure or way to entirely prevent the spread of herpes, the Centers for Disease Control and Prevention (CDC) described treatment options to reduce symptoms, outbreaks, and other precautions to minimize spread. One type of medication, antiviral drugs, can shorten outbreaks, lower recurrences, and even reduce the risk of transmission to a partner when taken as prescribed.

There are also drug-free ways to prevent the spread of herpes, but they're not foolproof, especially considering that many people don't even know they have the virus.

"There is an aspect of prevention that requires cautious sexuality on everyone's part," Dr. Handsfield said. That means never putting areas of your body that have an active herpes outbreak (either oral or genital sores) in direct contact with other people's mouths or genitals. For example, people with an active oral herpes outbreak shouldn't kiss anyone or perform oral sex on a partner.

In addition, latex condoms can help prevent the spread of genital herpes. Still, they don't eliminate the possibility of transmission because the sores can occur in areas that aren't covered by a condom.

It's also possible to spread herpes to different parts of your own body. Try not to touch any active sores; if you do, wash your hands immediately. Likewise, don't touch another part of your body after touching a sore or fluid from a sore without first washing your hands.

Neonatal Herpes Infections

A pregnant person can pass the herpes virus on to their newborn during delivery in what's called neonatal herpes. This can be potentially devastating for the baby, possibly leading to permanent neurocognitive disabilities and other issues.

"We worry about newborns acquiring HSV-1 or HSV-2 during birth," Dr. Wald said. "The highest risk of that is if the mother has...acquired herpes late in the pregnancy."

Doctors will often treat pregnant individuals who have genital herpes with medication during the last month of pregnancy to prevent an active outbreak when they go into labor, Dr. Handsfield said.

Living With Herpes

Other than stigma and discomfort if you have symptoms, infection with either HSV-1 or HSV-2 brings few long-term health problems for the average healthy adult. However, one major exception is HIV transmission.

"On a worldwide basis, having HSV-2 is an extraordinarily potent factor for HIV transmission," said Dr. Handsfield. People who have HSV-2 are up to six times more likely to contract HIV if they are exposed. Herpes sores not only provide a way for HIV to enter the body, but even when there are no active lesions, herpes multiplies the types of cells that HIV usually targets, increasing the risk of transmission.

When To See a Medical Provider

Consult with a healthcare professional if you think you have herpes to get the correct diagnosis and treatment plan. If you've already been diagnosed, talk with a medical provider if you have recurrent outbreaks as treatments exist that can prevent or reduce your symptoms. Also, during pregnancy, let your prenatal care provider know if you have herpes so that you can take steps to prevent transmission to your baby.

A Quick Review

Herpes is a common STI, and you may have it without knowing it. Some people never experience symptoms, and common symptoms can sometimes point to other conditions. Additionally, your partner(s) may not know they have the virus.

However, if you are aware you have this STI, there are steps you can take to keep yourself and your partner(s) healthy. These include taking any antivirals as prescribed and practicing safe sex by using a condom. Additionally, avoiding sexual contact during active outbreaks can also reduce the risk of transmission.

If you notice symptoms of HSV, or have concerns due to past or current partners, talk with a healthcare provider. The healthcare provider can help you determine your risk factors, establish a diagnosis, and discuss necessary treatment options.