The first bout follows contact with someone with herpes. The blisters will rupture, scab over, and dry up. The whole process takes 10 to 14 days. The sores do not cause scars.
Treatment can shorten the course by many days.
Once you get fever blisters, you usually can't shorten the time that you have them unless you start applying an antiherpes ointment as soon as any small bumps appear. These ointments require a prescription. If you don't have an antiherpes ointment, cover the fever blisters with petroleum jelly to reduce the pain and to promote healing. Your child needs the ointment prescribed by your physician. The ointment can reduce the severity of the sores only if treatment is started early.