Cold sores spread from person to person through close contact, such as kissing. They are usually caused by the herpes simplex virus type 1 (HSV) and, less commonly, by the herpes simplex virus type 2 (HSV). Both viruses can affect the mouth or genitals and can be transmitted through oral sex. Cold sores are contagious even if you don't see them.
Oral herpes is most commonly transmitted in people with an active outbreak or sore. Oral herpes can be contracted through intimate or personal contact (e.g., cold sores are caused by a virus called herpes simplex). Once you have the virus, it stays on your skin for the rest of your life. It sometimes causes a cold sore.
Once you've had an episode of herpes infection, the virus remains latent in nerve cells in the skin and can appear as another cold sore in the same place as before. The herpes virus is spread through physical contact, such as kissing, sharing a toothbrush, even sharing a drinking glass or through sexual contact. While the specific triggers that cause oral herpes to return are not clear, several factors may play a role. Sometimes, oral and genital herpes viruses can spread, even when there are no sores or blisters in the mouth.
Do not have oral sex until your cold sores are completely cured, as you could transmit genital herpes to your partner. The following are the most common signs and symptoms of a recurrent oral herpes simplex virus infection. Since oral herpes is spread through direct physical contact, the best prevention method is to avoid physical contact with a person's herpetic sores when an outbreak occurs. Kissing a baby if you have cold sores can cause neonatal herpes, which is very dangerous for newborns.
Since oral herpes can be confused with many other infections, including allergic reactions, the only ways to confirm the diagnosis are through a viral culture (PCR), blood test, or biopsy.