Herpes labialis (oral Herpes simplex)

Alternative names:

cold sore; fever blister; herpes simplex - oral

Definition:

An infection caused by the herpes simplex virus, characterized by an eruption of small and usually painful blisters on the skin of the lips, mouth, gums, or the skin around the mouth. See also herpes simplex.

Causes, incidence, and risk factors:

Herpes labialis (cold sores, fever blister) is an extremely common disease caused by infection of the mouth area with herpes simplex type 1. At least 1 out of 1000 people may be affected with this virus. Most people have been affected with the type 1 virus by the age of 20. The initial infection may cause no symptoms or mouth ulcers. The virus remains in the nerve tissue of the face. In some people, the virus reactivates and produces recurrent cold sores that are usually in the same area but are not serious. Herpes virus type 2 causes genital herpes and infection of babies at birth.

Both viruses are contagious. Contact can occur directly, or through contact with infected razors, towels, dishes, etc. The herpes virus can also infect the fetus and cause congenital abnormalities.

The first symptoms usually appear 1 or 2 weeks after contact with an infected person, or up to as late as 20 or more days after exposure. The lesions of herpes labialis usually last for 7 to 10 days, then begin to resolve. The virus may become latent, residing in the nerve cells, with recurrence at or near the original site. Recurrence is usually milder. It may be triggered by menstrual periods, sun exposure, illness with fever, or other unknown causes.