Health Topics for Infectious Diseases

Department of Internal Medicine: Infectious Diseases

Department of Internal Medicine: Travel Medicine

Fever blisters and cold sores

There are two types of herpes virus, Type 1 and Type 2. Herpes Simplex Virus Type 1 causes cold sores, canker sores, and fever blisters. The virus is related to Herpes Simplex Virus Type 2, which causes genital herpes. The fluid in the blisters from both types of viruses contains live virus and can easily be spread from one person to another with both types of viruses. Herpes Simplex Virus Type 1 can be spread by kissing, sharing food and drink glasses, or by not washing your hands after touching the blisters.

Once you are infected, the virus continues to live in the nerve cells of the skin, even after the blisters are gone. These blisters seem to reoccur after an injury to the skin, too much sun exposure, stress fatigue, food allergies, dental treatment, injury to lips or gums, pregnancy, hormonal changes caused by a woman's menstrual cycle, or from physical illness such as a cold. When the virus is active, it causes more and more cold sores, canker sores, and fever blisters. It is not possible to predict how often the blisters and sores will reoccur. Some people never have them again and other people have them regularly.

Herpes Simplex Virus Type 1 usually begins with a sensation of numbness, tingling, itching, or burning on a certain area of the skin, lips, or inside the mouth. About 24 hours later, a small cluster of tiny blisters appears. The blisters may be painful. Symptoms of a first attack may include mouth soreness that makes it uncomfortable to eat, drink, and sleep, fever, sore throat, swollen glands in the neck, and drooling in small children.

Over the next few days, the blisters break and fluid drains out. This fluid is very contagious. As the blisters dry, they become sores that are covered with a yellowish- dried crust. Usually the sores are gone within 1 to 2 weeks, but can sometimes last longer. They may return several times a year or a few years later.

Prevention of Herpes Simplex Type 1 disease is important. To prevent spreading the virus to other areas of the body or to another person, take the following steps:

• avoid touching any area of the body where there is tingling, itching, burning, or blisters (This is very important when the blisters are draining.)
• avoid kissing and other oral contact
• avoid sharing soaps, washcloths, and cosmetics (including lip balm)
• avoid sharing eating or drinking utensils and
• avoid sexual contact, which spreads the blisters to the genitals during oral-genital sex

It is also important to wash your hands frequently so that you do not spread the virus to other parts of your body. If you are caring for someone with this virus, do not touch the sores directly. Use gloves or gauze to apply medicine.

The treatment of Herpes Simplex Type 1 depends on how severe the blisters are and where they are located. If there are multiple sores, a healthcare provider may prescribe a special anti-viral medication that stops the virus from reproducing itself. This must be taken when the initial symptoms begin. It does not eliminate the virus from the body. Treatment may help shorten the length of any single outbreak. Some people take the medicine daily to stop outbreaks from recurring.

There are many over the counter (non-prescription) medications that can be used to treat canker sores, fever blisters, and cold sores. However, they may not work as well as a prescription medication.

If you have symptoms of herpes or get blisters or sores often, contact a provider for evaluation and treatment.

Last Reviewed 2005

Disclaimer: This content is reviewed periodically and is subject to change as new health information becomes available. The information provided is intended to be informative and educational and is not a replacement for professional medical evaluation, advice, diagnosis or treatment by a healthcare professional.

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