Herpes simplex virus
Cold sores are usually caused by the herpes simplex virus.
In most cases the virus is passed on in early childhoodfor example, when a child is kissed by a family member or friend with a cold sore.
The virus passes through the skin and travels up the nerves, where it lies inactive (dormant) until it's triggered at a later date.
Factors thought to trigger outbreaks of cold sores include:
However, in many cases there's no obvious trigger for an outbreak.
Cold sores can happen after having oral sex with a man or woman who has genital herpes .
Cold sores are small blisters that develop on the lips or around the mouth. They're caused by the herpes simplex virus and usually clear up without treatment within 7 to 10 days
You won't usually have any symptoms when you first develop the herpes simplex virus (a primary infection). An outbreak of cold sores may occur some time later.
Cold sores are usually caused by the herpes simplex virus type 1 (HSV-1). Occasionally, they can also be caused by the herpes simplex virus type 2 (HSV-2).
Cold sores usually clear up without treatment within 7 to 10 days. Antiviral creams can be used to ease your symptoms and speed up the healing time.