What Is a Cold Sore? A cold sore is a group of tiny, painful blisters caused by the herpes simplex virus (HSV). They're also called fever blisters or herpes simplex labialis. Up to 90% of people ...

Cold sores, also known as fever blisters, can appear on your mouth or lip and are usually caused by oral herpes or herpes simplex virus type 1 (HSV-1). “It’s extremely ubiquitous,” says Alexandra ...

Medically reviewed by William Truswell, MD Cold sores are contagious and spread through contact, such as kissing and sharing ...

Cold sores, also known as fever blisters, are common, contagious outbreaks caused by the herpes simplex virus type 1, with about 64% of people exposed by age 50. Often triggered by stress, illness or ...

The virus that commonly causes cold sores starts reshaping our genome within an hour of infection to boost its own growth, which scientists could take advantage of to treat severe cases. Billions of ...

Waking up with a spot on your lip is never a good feeling. Often cold sores or pimples are to blame, though telling the difference isn't always easy. They can look similar on the surface, but their ...

Mouth and lip sores are often caused by an injury, medical condition or sometimes herpes simplex virus. Learn how to soothe ...

Cold sores are an unhappy fact of life for an estimated 55 million Americans, say health experts. ``Some of my patients know they will get a cold sore whenever they go skiing or to the beach,'' says ...