Cold sores are small, painful, fluid-filled blisters. They are usually found at the border of the lip.

Cold sores will go away on their own within two weeks. Medications may help relieve symptoms or shorten the length of time you have them.

Herpes Simplex on the Lips
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Cold sores are caused by two types of herpes simplex viruses. Cold sores are very common. In most cases, people contract the virus as young children.

You may get the virus from:

  • Contact with the fluid from a cold sore of another person, or genital herpes sores
  • Contact with the eating utensils, razors, towels, or other personal items of a person with active cold sores
  • Sharing food or drink with a person with active cold sores
  • Contact with the saliva of a person who has the herpes virus even if no sores are present

The first episode of illness with herpes virus can cause a body-wide illness. After that, the virus lies quietly in the skin until it is reactivated. The reactivated virus causes a cold sore to appear.