Cause of fever blisters?


What causes fever blisters on lips and how should they be treated? Also, what is the difference between fever blisters and shingles?

— Sores

Dear Sores,

Fever blisters, or what is more commonly referred to as cold sores, can occur around a person's mouth, or on one's lips and face. Colds sores are commonly caused by the herpes simplex 1 virus (HSV-1). Shingles is also caused by the herpes virus (herpes zoster), but has slightly different symptoms and methods of transmission.  

More about fever blisters and cold sores: HSV-1typically affects the mouth and facial areas, although it can be transmitted to the genital area through oral-genital sex. Herpes simplex two (HSV-2) most commonly affects the genital area, but may also cause blisters on the mouth. The virus can be transmitted through direct contact with a lesion, through contact with fluid from a lesion, and through contact with the virus even when no symptoms are present in the infected person.

The first outbreak is usually the worst and lasts the longest. After this outbreak, the virus lives in the nerve pathways around the area of the initial infection. The virus symptoms can and probably will recur, at the same site, but they will be much less serious than the first outbreak. Often HSV-1 may be reactivated because of circumstances such as extensive sun exposure, elevated stress, fever, and hormone fluctuations.

There is no cure for HSV-1 (or HSV-2), but cold sores typically resolve on their own in about two weeks. There are some medications (both prescription and over-the-counter) available to speed up the healing process. Some additional over-the-counter medications may alleviate pain, burning, and itching. Because active cold sores are very contagious, it is recommended that contact with others, such as kissing or sharing cups or utensils, (that come in contact with the cold sore) be limited. It’s also a good idea to make sure wash your hands frequently if you have to touch your cold sore, so that you don’t accidently transmit the virus to another part of your body, such as the eyes or genitals. Managing stress, eating well, being physically active, and getting adequate sleep are all ways to help prevent cold sores from recurring.

Now on to the difference between fever blisters and shingles: herpes zoster is the medical term for shingles, and it is an infection of the nerves in certain areas of the skin. It is caused by the varicella-zoster virus, which also causes chickenpox, which can remain dormant (i.e. not active) in the body even after recovery. For reasons that are not determined as of yet, the virus may be reactivated later in life which results in shingles. Characteristic symptoms of shingles include a painful rash of small, crusting blisters, most often on a strip of skin over the ribs on one side of the body (but can be found in other parts of the body as well). Shingles is not transmitted from person to person. Interestingly, if someone who has never had chickenpox comes in contact with someone who has active shingles, they may develop chickenpox, but not shingles. About one million Americans get shingles each year, making it a pretty common disease. It mainly affects people over the age of 60 years, and the incidence rises with age. Herpes zoster is also common in people with compromised immune systems.

For more information about any of these types of blisters, check out the related Q&As and the American Sexual Health Association  Herpes Resource Center. Consider making a visit to your health care provider. Hope this helps!

Last updated May 29, 2014
Originally published Oct 20, 1995

Submit a new comment


This question is for testing whether or not you are a human visitor and to prevent automated spam submissions.

The answer you entered for the CAPTCHA was not correct.