Herpes labialis is 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. These blisters are commonly called cold sores or fever blisters.

Alternative Names

Cold sore; Fever blister; Herpes simplex - oral

Causes, incidence, and risk factors

Herpes labialis is an extremely common disease caused by infection of the mouth area with herpes simplex virus, most often type 1. Most Americans are infected 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 usually causes genital herpes and infection of babies at birth but can also cause herpes labialis. Herpes viruses are contagious. Contact can occur directly, or through contact with infected razors, towels, dishes, etc. Occasionally, oral/genital contact can spread oral herpes to the genitals (and vice versa), so people with active herpes lesions on or around their mouths or on their genitals should avoid oral sex. The first symptoms usually appear within 1 or 2 weeks, and as late as 3 weeks, after contact with an infected person. 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 menstruation, sun exposure, illness with fever , stress, or other unknown causes.

Signs and tests

Diagnosis is made on the basis of the appearance and/or culture of the lesion. Examination may also show enlargement of lymph nodes in the neck or groin. Viral culture or Tzanck test of the skin lesion may reveal the herpes simplex virus.

Treatment

Untreated, the symptoms will generally subside in 1 to 2 weeks. Antiviral medications may be given by mouth to may shorten the course of the symptoms and decrease pain. Wash blisters gently with soap and water to minimize the spread of the virus to other areas of skin. An antiseptic soap may be recommended. Applying ice or warmth to the area may reduce pain. Take precautions to avoid infecting others (see Prevention).

Expectations (prognosis)

Herpes labialis usually disappears spontaneously in 1 to 2 weeks. It may recur. Infection may be severe and dangerous if it occurs in or near the eye, or if it happens in immunosuppressed people.

Complications

Calling your health care provider

Call for an appointment with your health care provider if symptoms indicate herpes labialis and symptoms persist for longer than 1 or 2 weeks. Also call if symptoms are severe, or if you have a disorder associated with immunosuppression and you develop herpes symptoms.

Prevention

Avoid direct contact with cold sores or other herpes lesions. Minimize the risk of indirect spread by thoroughly washing items in hot (preferably boiling) water before re-use. Do not share items with an infected person, especially when herpes lesions are active. Avoid precipitating causes (especially sun exposure) if prone to oral herpes. Avoid performing oral sex when you have active herpes lesions on or near your mouth and avoid passive oral sex with someone who has active oral or genital herpes lesions. Condoms can help reduce, but do not entirely eliminate, the risk of transmission via oral or genital sex with an infected person. Unfortunately, both oral and genital herpes viruses can sometimes be transmitted even when the person does not have active lesions.