Cold Sores

Overview of Cold Sores

Cold sores or “fever blisters” occur on the lips or around the margins of the lips. The medical term for cold sores, Herpes Labialis, refers to the Herpes virus Type1 (HSV-1) that most often causes theses sores, though Herpes virus Type 2 (HSV-2) less often can also be a cause.

A person’s first oral exposure to the Herpes virus is usually without symptoms. The virus then becomes dormant. Reactivation of the dormant virus can occur and is often precipitated by a physical stimulation of the area that triggers the appearance of sores. HSV-1 oral infections are more likely to repetitively recur as cold sores than HSV-2 caused infections.

Signs & Symptoms

The signs and symptoms of the first episode of cold sores may be quite severe, with soreness and swelling of the gums, lips and throat, muscle aches, fever, and swollen lymph nodes. Sometimes with this first episode, small blisters may also appear.

Other subsequent episodes can show:

  • individual or clustered blister-like sores on the lip margin
  • blisters often preceded by a “prodromal” tingling, burning, itching of the skin area within 72 hours of the appearance of the sores
  • blisters usually progressing to an ulcerated area that crusts over & heals within 7-10 days


The only sure way to prevent cold sores is to avoid skin-to-skin oral contact with people known to have the virus whether or not they are symptomatic (sometimes the virus is shed from the nearby mucosal surface intermittently, even when no visible sores are present). Avoiding oral-genital contact with people known to have genital herpes (which may be HSV-1 or HSV-2) is similarly important.

Once an initial exposure or outbreak has occurred, several strategies can be employed to try to prevent the recurrence of the cold sores:

  • Use of sunscreens (both skin & lip balm) or avoidance of sun exposure, extreme cold or skin trauma/irritation where prior sores occurred, since these factors may trigger a recurrence.
  • Stress reduction, nutritious diet, adequate rest/sleep, since physical or emotional stress can be associated with increased episodes or outbreaks

People who identify predictable “triggers” but are unable to reduce recurrence with lifestyle measures, or those whose recurrent cold sores appear to be random or frequent, may benefit from antiviral medications that may be used prophylactically with significant reductions in the frequency of outbreaks.


  • Keep clean and dry to allow the cold sores to crust over and heal, usually within 1-2 weeks
  • Avoid rubbing or picking at the cold sores to avoid spreading the virus to other areas or other persons, & to avoid secondary bacterial infection
  • Non-specific pain medication (e.g. Advil, Tylenol) may be effective in reducing any associated pain.

Both prescription and over-the-counter topical and oral medications specifically for use in treating cold sores are available and should be started with the first symptoms of recurrence for the most effective treatment.

How We Can Help

If you would like to be seen by our medical staff, please contact our Appointment Desk to schedule an appointment. Also, our Advice Nurse service is available at no charge for all UC Davis students to discuss health concerns and the need for medical care.