Cold sores, also known as fever blisters, are small, liquid-filled blisters that often develop around the mouth and affect as many as 2 in 3 people worldwide.
A cold sore is caused by the herpes simplex virus (HSV) type 1, and occasionally HSV type 2. These sores can develop on different body parts, although they’re commonly found around the lips. Some people might get cold sores around their noses and cheeks as well.