The symptoms of recurrent fever blister attacks usually are less severe than those experienced by some people after an initial infection. Recurrences appear to be less frequent after age 35. Many people who have recurring fever blisters feel itching, tingling or burning in the lip 1 to 3 days before the blister appears. Several factors weaken the body's defenses and trigger an outbreak of herpes. These include emotional stress, fever, illness, injury and exposure to sunlight.
Many women have recurrences only during menstruation.
One study indicates that susceptibility to herpes recurrences is inherited. Research is under way to discover exactly how the triggering factors interact with the immune system and the virus to prompt a recurrence of fever blisters. Currently them is no cure for fever blisters. Some medications can relieve some of the pain and discomfort associated with the sores, however. These include ointments that numb the blisters, antibiotics that control secondary bacterial infections, and ointments that soften the crests of the sores.