by Rick Alan
Cold sores are small, painful, fluid-filled blisters, usually on the lips or gums.
Cold sores are usually caused by the herpes simplex 1 virus, but sometimes caused by the herpes 2 virus that causes genital herpes. 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. The virus then lies dormant until it is reactivated. Once reactivated, it results in painful cold sores, usually located at the border of the colored part of the lip.
The virus can be spread by:
Contact with the eating utensils, razors, towels or other personal items of a person with active cold sores
Contact with the fluid from a cold sore of another person
Contact with the saliva of a person who has the herpes simplex virus
Sharing food or drink with a person with active cold sores
A risk factor is something that increases your chance of getting a disease or condition. Infection with the virus that causes cold sores 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:
Certain foods or drugs
Exposure to sun
Infection, fever, cold, or other illness
Physical injury or trauma
Physical or emotional stress
Weakened immune system
Cold sores often form without an identifiable trigger.
The first episode of herpes simplex 1 infection may result in 3 to 14 days of:
Aches and pains
Swollen glands in the neck
Swollen, sore throat
After this initial illness has passed, the virus lies dormant until reactivated. 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:
After a few days, drying of the blister, which then forms a yellow crust and shallow ulcers
Pain, tingling or itching for a day or two before the blister appears
Small, painful, fluid-filled, red-rimmed blisters
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 7-20 days. Treatments for blisters on the lips, mouth, or skin include:
Antibiotic drugs if the blister becomes infected by bacteria
Antiviral creme or ointment if you suffer from frequent herpes simplex 1 virus outbreaks
Non-prescription cold sore/fever blister cremes and ointments to lessen pain
Non-prescription pain relief drugs to lessen pain and discomfort
Not rubbing or scratching blisters
Oral antiviral medications, such as Zovirax® (acyclovir) or Denavir® (penciclovir), may be given the moment you feel a cold sore coming on. These medications can decrease discomfort, and help cold sores go away more quickly.
Putting ice on blisters to lessen pain and promote healing
To prevent the spread of the herpes simplex 1 virus:
Avoid skin contact, kissing or sharing food, drink or personal items with people with active cold sores.
If you have an active cold sore, avoid touching the infected area (to avoid spreading the virus to other people and/or other parts of your body).
To prevent recurring outbreaks of cold sores or blisters:
Avoid long periods of time in the sun.
Get adequate rest and relaxation to minimize stress.
Use sun block on lips and face when in the sun.
Last reviewed: November 2003 by Elizabeth Smoots, MD .