The herpes simplex virus-1, which has laid dormant in the body, reactivates or "wakes up" from it inactive state.
The virus travels toward the area where the cold sore decides to show up (like a person’s lip) via the nerve endings.
The area below the skin’s surface, where the cold sore is going to appear, starts to tingle, itch, or burn.
A red bump appears in the area about a day or so after the tingling.
The bump blisters and turns into a cold sore.
After a few days, the cold sore dries up and a yellow crust forms.
The scab-like yellow crust falls off and leaves behind a pinkish area where the cold sore once was.
The redness fades away as the body heals and sends the herpes simplex virus back to "sleep” or it’s inactive state