Cold sores are caused by the herpes simplex virus (HSV).
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.
as a medical treatment ,herpes are treated by acyclovir creams .