How can cold sores be transmitted?

Depends: Cold sores are herpes virus most often. They lay in wait in the nerve endings. When you can see them, they are contagious, but hard to transmit. However, they are shedding even when you can't see the sore. The virus is actually hard to catch. Open sores, compromised skin or mucous membranes or a weak immune system all allow the virus to 'take'.

Contact: Kissing, sex. Any touching of a mucosal body surface to a cold sore can cause spread. Touching with a finger and going to a mucous membrane, like the inside of your nose can cause spreading. These viruses are highly contagious. Eyes, genitalia, etc, are also common spread sites.

Direct Contact: Cold sores are caused by the herpes simplex virus (hsv). They are typically transmitted through broken skin. Sometimes through kissing, sharing eating utensils or drinking cups, or other forms of touching another person's saliva.