Illustration of cold sore on different skin colors. A cold sore is a cluster of fluid-filled blisters. Healing often occurs in two to three weeks without scarring. Cold sores are sometimes called fever blisters.
Mayo Clinic does not endorse companies or products. Advertising revenue supports our not-for-profit mission.
Check out these best-sellers and special offers on books and newsletters from Mayo Clinic Press.
Help us advance cardiovascular medicine.