Cold sores are caused by the herpes simplex virus; Cold sores, sometimes called fever blisters, are groups of small blisters on the lip and around the mouth. The skin around the blisters is often red, swollen, and sore. The blisters may break open, leak a clear fluid, and then scab over after a few days. They usually heal after several days to 2 weeks.
The herpes simplex virus usually enters the body through a break in the skin around or inside the mouth. It is usually spread when a person touches a cold sore or touches infected fluid-such as from sharing eating utensils or razors, kissing an infected person, or touching that person's saliva. A parent who has a cold sore often spreads the infection to his or her child in this way. Cold sores can also be spread to other areas of the body.
After you have been infected with the virus, there is no sure way to prevent more cold sores. But there are some things you can do to reduce your number of outbreaks and prevent spreading the virus.
* Avoid the things that trigger your cold sores, such as stress and colds or the flu.
* Always use lip balm and sunscreen on your face. Too much sunlight can cause cold sores to flare.
* Avoid sharing towels, razors, silverware, toothbrushes, or other objects that a person with a cold sore may have used.
* When you have a cold sore, make sure to wash your hands often, and try not to touch your sore. This can help keep you from spreading the virus to your eyes or genital area or to other people.
* Talk to your doctor if you get cold sores often. You may be able to take prescription pills to prevent cold sore outbreaks.
All taken from this website: http://www.webmd.com/skin-problems-a...verview?page=2