Cold sores are caused by a virus known as the Herpes Simplex virus.
A cold sore can be triggered by a cold or fever and can also be triggered by being stressed out.
Sun exposure and trauma to the lips can also trigger a cold sore to break out.
Cold sores normally go away within 2 weeks on their own without treatment but if you apply some cold sore medicine or even some baby orajel to the cold sore it will get rid of the cold sore much faster as in 1 to 2 days.