Cold sores are usually caused by the herpes simplex 1 virus. It can sometimes be caused by the herpes 2 virus that causes
. The two viruses are related, but different. The virus invades the skin, then lies dormant for weeks or months before causing inflammation and blistering.
In most cases, people contract the virus as infants or young children. The first episode of illness with herpes simplex 1 virus causes a systemic illness. Then the virus lies dormant until it is reactivated. This results in painful cold sores. They are usually located at the border of the colored part of the lip.
The virus can be spread by:
Contact with the fluid from a cold sore of another person, or sores of genital herpes in most cases of the herpes 2 virus
Contact with the eating utensils, razors, towels, or other personal items of a person with active cold sores
Sharing food or drink with a person with active cold sores
Contact with the saliva of a person who has the herpes simplex virus
Infection with this virus is so common that everyone is considered at risk.
Once the herpes simplex 1 virus is present in the body, the following risk factors can trigger cold sores to form:
In the day just prior to the virus reappearing as a cold sore, you may notice some itching, burning, or pain in the area where the cold sore will appear.
Symptoms of cold sores on the lips, mouth, or skin include:
Small, painful, fluid-filled, red-rimmed blisters
Pain, tingling, or itching for a day or two before the blister appears
After a few days, drying of the blister, which then forms a yellow crust and shallow ulcers
The doctor will ask about your symptoms and medical history, and examine the blisters. Usually, the doctor can easily diagnose a cold sore by looking at it. Cold sores have a relatively classic appearance. In rare cases, the doctor may need to take a piece of a blister to analyze it or take a blood sample for testing.
Cold sores will usually heal within 7-10 days.
for blisters on the lips, mouth, or skin include:
Putting ice on blisters to lessen pain and promote healing
Not rubbing or scratching blisters
Nonprescription pain relief drugs to lessen pain and discomfort
Nonprescription cold sore/fever blister cremes and ointments to lessen pain
Antibiotic drugs if the blister becomes infected by bacteria
Antiviral cream or ointment, although the evidence for its effectiveness is not strong
Oral antiviral medications may be given the moment you feel a cold sore coming on or could be taken on a regular basis to suppress frequent outbreaks. To decrease discomfort and help cold sores go away more quickly, you may be given one of the following:
Spruance S, Bodsworth N, Resnick H, et al. Single-dose, patient-initiated famciclovir: a randomized, double-blind, placebo-controlled trial for episodic treatment of herpetic labialis.
J Am Acad Dermatol
Spruance SL, Jones TM, Blatter MM, Vargas-Cortes M, et al. High-dose, short-duration, early valacyclovir therapy for episodic treatment of cold sores: results of two randomized, placebo-controlled, multicenter studies.
Antimicrobial Agent Chem
Please be aware that this information is provided to supplement the care
provided by your physician. It is neither intended nor implied to be a
substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER
IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the
advice of your physician or other qualified health provider prior to
starting any new treatment or with any questions you may have regarding a