Cold sores are small blisters that appear on or around your mouth, sometimes called 'oral herpes'. Most cold sores heal on their own within 2 weeks and don't leave scars. However, they're Herpes aidsmap Herpes labialis, also called a cold sore, is usually caused by HSV 1. The virus stays in the body and can become active again later, so cold sores may come and Can Sex Toys Transmit STDs? What the Science Says Genital Herpes: Causes, Symptoms, Treatment & Prevention