Be very careful if it comes out in your mouth, you are infected
Cold sores, also known as fever blisters, are a common viral infection primarily caused by the herpes simplex virus type 1 (HSV-1). In some cases, herpes simplex virus type 2 (HSV-2)—usually associated with genital herpes—can also lead to cold sores, especially through oral-genital contact. What Causes Cold Sores? Cold sores are highly contagious and spread ...