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Sorely Confused - Cold Sore, Canker Sore, Chancre?

What is the Difference Between Cold Sores, Canker Sores, & Chancre?

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Updated June 03, 2014

Written or reviewed by a board-certified physician. See About.com's Medical Review Board.

People suffer from an array of sores on their mouths and their genitals, but there are three types of sore that by virtue of their name and location are frequently confused. These are canker sores, the cold sores caused by oral herpes, and the chancre sores caused by syphilis. (It doesn't help that chancre rhymes with canker, so sometimes people aren't certain exactly what their doctor has said.)

1. Cold Sores

Girl with cold sore
Peter Dazeley/Photographer's Choice RF/Getty Images
Cold sores, or fever blisters, are caused by a herpes virus. These small painful blisters are most often found around the lips, and usually break open, crust over, and heal over the period of a week to 10 days. Cold sores are usually caused by HSV-1, the type of virus most often associated with oral herpes, but they can also be caused by HSV-2, which is more often associated with genital herpes. Both types of herpes virus are extremely contagious, especially when active lesions are present, and they can be transmitted by casual as well as sexual contact. In other words, friendly kissing puts you at risk as well as anal, vaginal, and oral sex. Herpes transmission may also be associated with exposure to infected objects such as eating utensils and razors, and it can even happen when no symptoms are present.

2. Canker Sores

Photo Courtesy of CDC/Sol Silverman, Jr., DDS (1999)
Canker sores are ulcers that occur in the soft tissues inside your mouth. Although they are associated with various nutritional and immunological deficiencies, canker sores are not contagious or sexually transmitted. They are, however, more common in individuals with acute HIV infection, because of its negative effects on the immune system.

Canker Sores are also known as apthous ulcers. They are usually round white sores with a red border. Canker sores can remain painful for several days, but generally heal within one to three weeks. If you have a canker sore that is particularly large, uncontrollably painful, lasts longer than three weeks, or accompanied by a high fever, seek the attention of a healthcare practitioner.

3. Chancre

Photos courtesy of the CDC/Dr. Gavin Hart; Dr. N.J. Fiumara; Dr. Dancewicz

The round, usually painless, sore that is the first stage of a syphilis infection is known as a chancre. Although not usually found on the face, the similarity in names between "canker sores" and "chancre" has been known to confuse more than a few people. Primary syphilis chancre are most often found on the genitals, but they can also be found on the anus, mouth, lips, tongue, tonsils, fingers, breasts, and nipples.

Because chancres are painless, they often go unnoticed. This means that, without testing, some people can be infected with syphilis for a long time before they notice any symptoms. This is particularly true when chancres occur within the mouth, which is one reason that transmission through oral sex has made a significant contribution to the syphilis epidemic over the past few years.

Next, learn how to have safer sex and reduce your risk of getting an STD...

Sources:
Cold Sores from The Mayo Clinic.
Canker Sores from The Mayo Clinic.
Syphilis from the CDC.

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