10 Causes and Treatments for Cold Sores

Cause: Contact with an Infected Person

Let's start our look at cold sore causes with the first and obvious one: Contact with a carrier of the virus.

You cannot get a cold sore, also called a fever blister, unless you first get the virus from another person [source: Mayo Clinic].

For those who don't have the virus, do not share anything that could come in contact with an active lesion on another person. Don't share eating utensils, lip balm, towels ... anything that may touch the sore [source: Mayo Clinic].