Can Oral Herpes Be Spread to Genitals?

A cold sore on the lower lip on the second day after onset. Image: CDC

Herpes simplex virus is mystifying, fascinating, and sneaky. Mystifying because we have yet to unravel all of its secrets; fascinating because when we do uncover one of its mysteries, we are amazed by the capabilities of such a tiny, microscopic object; and sneaky because it enters our bodies by stealth and conceals itself in our cells, taking us by surprise when it comes out of hiding and causes outbreaks of blisters and other lesions.

It can also be confusing. Herpes simplex virus actually comes in two flavors: HSV-1 and HSV-2. HSV-1 is associated more with oral herpes, which can cause “cold sores,” a type of blister that appears on the lips or face. HSV-2 is associated more with genital herpes, which can cause blisters and other lesions in the genital area. It used to be standard to describe HSV-1 as an “above-the-waist” infection and HSV-2 as a “below-the-belt” infection — but now many researchers are pointing out that it’s more appropriate to say that HSV-1 is both an orally and genitally transmitted infection while HSV-2 is a predominantly genitally transmitted infection. If HSV-1 enters the body in the genital area, it can cause a genital herpes infection — and likewise, if HSV-2 enters the body in the facial area, it can cause an oral herpes infection.


Using condoms and dental dams during oral sex reduces risk of herpes transmission.


What exactly is a cold sore, anyway? A cold sore, also known as a fever blister, is a cluster of blisters that can pop up around the lips or even in the mouth. Sometimes, cold sores are so painful that eating or drinking is difficult, and in extreme cases sufferers must be treated for dehydration. An especially severe infection could also cause high fever or swollen lymph nodes, and in young adults a first oral HSV-1 infection might be misdiagnosed as tonsillitis, possibly leading to unnecessary tonsillectomies. Most symptomatic first-time cold-sore outbreaks occur during childhood, and take about two or three weeks to clear up. Luckily, the first infection is almost always the most severe, and when the infection is reactivated it usually happens without symptoms.

Because both cold sores and genital herpes are caused by herpes simplex viruses, and because oral herpes is so common, many people are concerned that they might be more vulnerable to acquiring a genital herpes infection than they previously thought. They might have a lot of questions, and if they’ve sought answers to those questions, they might have heard a lot of conflicting answers. Let’s see what the scientific literature has to say.

  • Can I get genital herpes if someone with cold sores performs oral sex on me?

Because HSV-1, the virus responsible for most oral herpes infections, can also cause genital herpes, many people wonder if someone with cold sores can transmit the virus to someone else by performing oral sex, resulting in a genital herpes infection. Other people wonder if HSV-1 can be transmitted via oral contact with the anus, resulting in a herpes infection in the rectal area. The answer to these questions is: Yes! Continue reading

STD Awareness: Oral Herpes

A transmission electron micrograph reveals HSV particles. Image: Fred Murphy, CDC

One of the most common sexually transmitted diseases is herpes, which most people associate with “outbreaks” in the genitals. In actuality, most cases have no symptoms, and the majority of people with genital herpes don’t know they have it. Herpes simplex virus, which causes genital herpes, can also infect facial nerves around the mouth, and its “outbreaks” include blisters called cold sores.

A cold sore outbreak involves an “eruption” of blisters around the mouth, which slowly heal as the virus returns to dormancy. Most cold sores are caused by herpes simplex virus type 1, or HSV-1. Around 60 percent of Americans are infected with HSV-1, and most of these infections are oral, asymptomatic, and acquired in childhood through nonsexual contact. Despite how common this infection is, only 20 to 40 percent of us actually get cold sores — and an even smaller percentage experience cold sores more than once a year. The rest of us don’t get cold sores at all, even if we are infected with HSV-1. That’s one quirk about HSV — an infection is permanent and incurable, but most people never have symptoms!


The virus that causes oral herpes can also cause genital herpes.


Making matters more confusing, there’s a related virus called HSV-2, which most people associate with genital herpes. However, HSV-1 can also cause genital herpes, and anyone with an HSV-1 infection in the facial area has the potential to transmit the virus to a partner’s genitals while performing oral sex — whether or not cold sores are present. However, when HSV-1 strikes the genitals, the infection is usually milder, with fewer (if any) recurring outbreaks. Additionally, a previous HSV-1 infection in the facial area might make you more resistant to acquiring an HSV-1 infection in the genital area — but it doesn’t confer total immunity. Continue reading