Herpes labialis is an infection caused by the herpes simplex virus. It leads to the development of small and usually painful blisters on the skin of the lips, mouth, gums, or lip area. These blisters are commonly called cold sores or fever blisters.

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 (to infected mothers), but may also cause herpes labialis.

Herpes viruses are contagious. Contact may occur directly, or through contact with infected razors, towels, dishes, and other shared articles. Occasionally, oral-to-genital contact may spread oral herpes to the genitals (and vice versa). For this reason, people with active herpes lesions on or around the mouths or on the 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.

Warning symptoms of itching, burning, increased sensitivity, or tingling sensation may occur about 2 days before lesions appear.

• Skin lesions or rash around the lips, mouth, and gums
• Small blisters (vesicles) filled with clear yellowish fluid
  • Blisters on a raised, red, painful skin area
  • Blisters that form, break, and ooze
  • Yellow crusts that slough to reveal pink, healing skin
  • Several smaller blisters that merge to form a larger blister
• Mild fever (may occur)

Diagnosis is made on the basis of the appearance 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.

Untreated, the symptoms will generally subside in 1 to 2 weeks. Antiviral medications given by mouth may shorten the course of the symptoms and decrease pain.

Sores caused by Herpes often come back again and again. The antiviral medicines work best if you take it when the virus is just starting to come back -- before you see any sores. If you the virus returns frequently, your doctor may recommend that you take the medicines all the time.

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).

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.

• Spread of herpes to other skin areas
• Secondary bacterial skin infections
• Recurrence of herpes labialis
• Generalized infection -- may be life-threatening in immunosuppressed people, including those with atopic dermatitis, cancer, or HIV infections
• Blindness

Herpes infection of the eye is a leading cause of blindness in the US, causing scarring of the cornea.

Call for an appointment with your health care provider if symptoms indicate herpes labialis and symptoms persist for more than 1 or 2 weeks.

Call if symptoms are severe, or if you have a disorder associated with immunosuppression and you develop herpes symptoms.

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.