Also known as fever blisters, cold sores are small red inflamed blisters that appear on the lip and on the area around the mouth. These blisters can crack open, leak fluid and turn into scab. This problem is caused by the herpes simplex virus, which comes in two types: HSV-1 and HSV-2. Both types can cause cold sores.
The initial symptom is usually an aching sensation around the mouth. A person may also have fever and swollen glands in the neck. Some cold sores can go away on their own. To speed up healing, check out this technique from the post below.