What are fever blisters (cold sores)?
These are common names for fluid filled blisters that commonly occur on the lips. They also can occur in the mouth, particularly on the gums and roof of the mouth (hard palate), but this is rare. Fever blisters are usually painful; in fact, the pain may precede the appearance of the lesion by a few days. The blisters rupture within hours, then crust over. They last about 7-10 days. The time from blister rupture until the sore is completely healed is the time of greatest risk for spread of infection. The virus can spread to your own eyes and genitalia, as well as to other people.
