Cold sores are small blisters that form around the mouth or on the lips. They are caused by the herpes simplex virus. The first attack of the virus may cause a flulike illness. The virus then lies dormant, but it may be reactivated and cause cold sores In many cases, an outbreak of cold sores is preceded by a tingling sensation on the lips.
This is followed by the appearance of small blisters that enlarge and become painful and itchy.
The blisters then burst and become crusty, before gradually disappearing.
Cold sores usually clear up by themselves within about 7 to 10 days. Treatment with an over-the-counter antiviral cream may prevent individual outbreaks if used at the first sign of tingling.
However, it does not eliminate the virus or prevent further attacks.