Fever blisters, also called cold sores, are fluid-filled blisters that appear on the border of the lips and on or around the nose. They are the result of a very contagious virus that affects most of the population at one time or another.
Causes
Fever blisters are caused by a type of herpes simplex virus. It enters the body most often through the mouth or nose areas, where the skin is easier to penetrate.
At first, characteristic blisters may not result. Antibodies (protective substances) in the body defend against the invading virus. The inactivated virus withdraws to a nearby nerve, where it remains until stress to the body or a diminished capacity to fight off infection triggers a recurrence.
When the virus is reactivated, it overruns the body's protective system and progresses back along the nerve to the general area of original infection. Factors that seem to bring on the appearance of blisters include fever, colds, menstruation, skin injury from dental work, excessive sun and wind exposure, and emotional stress.
Symptoms
Initially, the virus may present no symptoms, so some people are unaware of infection. For others, the infection begins with numbness or tenderness in the affected area. Then small, fluid-filled blisters appear. These blisters break, encrust, and heal within one to two weeks.
Complications
Occasionally, excessive pain or swelling of lymph nodes develops. These symptoms may indicate a secondary bacterial infection that needs medical attention.
Other complications can be more serious. Herpes simplex keratitis is a painful viral infection of the cornea (transparent covering of the eye) that can result in blindness if not treated. Herpes virus has been shown to cause serious complications in infants and extremely ill patients who contract the disease.
Treatment
Treatment involves relieving symptoms, since there is no known cure for fever blisters. Some over-the-counter remedies may relieve pain and help dry blisters. Topical corticosteroid creams, however, should not be applied unless prescribed by a physician; the possibility of spreading infection increases because the corticosteroid can depress the immune response. Some physicians recommend topical acyclovir cream or ointment for severe blisters.
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