Herpes Simplex Virus (HSV) Mouth Infection - Cedars-Sinai

What causes an HSV mouth infection?

The virus is spread by skin-to-skin contact with someone who carries the virus. Most people with oral herpes were infected during childhood or as young adults from nonsexual contact with infected saliva. It can be passed by kissing, touching the infected person's skin, or sharing infected objects, such as lip balm, silverware, or razors.

The 2 most common forms of the virus are:

• Herpes simplex virus type 1 (HSV-1). HSV-1 is most often linked to infections of the mouth.
• Herpes simplex virus type 2 (HSV-2). This type is most often linked to genital herpes infections.

Having a cold sore doesn't mean that you have a sexually transmitted infection (STI). But both types of HSV can infect both the mouth and the genitals.

Once infected, a person will have the herpes simplex virus for the rest of their life. When the virus is not active, it is dormant in a group of nerve cells. Some people never have any symptoms from the virus while others have periodic outbreaks of infections.

It is not clear what triggers the virus to return. But the risk factors below may play a role:

• Long or intense exposure to sunlight
• A recent fever
• Emotional stress
• Menstruation
• Surgery
• Physical injury

Recurrent outbreaks are more common in the first year after the initial episode. After that, the outbreaks lessen in frequency and severity as the body builds antibodies to the virus.