These cold sores are also called fever blisters and a common viral infection. When they burst, they form a scab that can last several days. Usually they heal within two to three weeks without leaving a scar. They are caused by the herpes simplex virus through close person to person contact. PS: Cold sores are contagious even if you don’t see them. . . . . . #sexualhealth #coldsore #coldsores #herpesgenital #hiv #std #herpes #herpesawareness