Sorely Confused: The Difference Between Cold Sores, Canker Sores, and Chancres

People can experience an array of sores. Three of these types of sores are, by virtue of their name and where they occur, frequently mixed up: cold sores, chancres, and canker sores.

  • Cold sores are mouth sores caused by the herpes simplex virus (HSV), which can be passed from person to person through saliva or close contact.
  • Chancres are sores caused by syphilis, a sexually transmitted disease. They can appear on the mouth, but also on the genitals.
  • Canker sores occur in the mouth. Their appearance is similar to cold sores, though they are not caused by an infection and cannot be transmitted to someone else.

You should always ask your healthcare provider to clarify exactly what you have and what's causing it. Though these sores may seem similar, their differences can be important to treatment and prevention strategies.

   Cold sore  Chancre  Canker Sore
Contagious  √  √  
Location  Around mouth Mouth or genitals  Inside mouth
Characteristics Blister-like, painful Round, firm, painless White with red border, painful

Cold Sores (Oral Herpes)

Oral herpes (cold sore)

DermNet / CC BY-NC-ND 

Cold sores—a.k.a. fever blisters or oral herpes—are small and painful blisters that are most often found around the lips. They usually break open, crust over, and heal over the period of a week to 10 days.

Cold sores are usually caused by HSV-1, which is one type of herpes virus. They can also be caused by HSV-2, though that type is more often associated with genital herpes.

Both types of herpes virus are extremely contagious. This is especially true when active lesions are present, although herpes can be transmitted when there are no sores as well.

While it's possible to get an oral herpes infection through sexual contact, most cold sores are caused by HSV-1 transmitted during childhood. For example, a young person can get herpes when an infected parent gives them a kiss.

You can also get oral herpes from using infected objects, such as eating utensils and razors.

Of the three types of sores discussed in this article, only cold sores are caused by herpes.

Chancre Sores

Chancres are the first stage of a syphilis infection. Primary syphilis chancres are most often found on the genitals. They can also be found on the anus, mouth, lips, tongue, tonsils, fingers, breasts, and nipples.

Chancre are round, firm, and usually painless. Because they don't typically cause discomfort, they often go unnoticed. This is particularly true when chancres occur within the mouth.

This means that, without testing for syphilis, some people can be infected for a long time before they notice any symptoms.

Chancres in the mouth are one reason that transmission through oral sex has made a significant contribution to the syphilis epidemic over the past few years.

Since chancre is pronounced almost just like canker, the terms have been known to confuse more than a few people. Fortunately, chancres are most commonly referred to as chancres and not chancre sores.

Unlike cold sores and canker sores, a chancre is usually painless. These sores are caused by syphilis, which can be treated with antibiotics.

Canker Sores

Canker sores inside of bottom lip

frank600 / Getty Images

Canker sores (aphthous ulcers) are non-cancerous ulcers that occur in the soft tissues inside the mouth. They are usually round, white sores with a red border and can remain painful for several days.

It is unclear exactly what causes canker sores, but triggers may include stress, minor injury inside the mouth, food sensitivities, and various nutritional deficiencies.

Unlike cold sores, canker sores are not sexually transmitted. They are also not contagious, though they may be associated with certain contagious infections.

For example, canker sores are more common in individuals with acute HIV infection because of the virus's negative effects on the immune system.

Most canker sores do not need treatment. They generally heal on their own within one to three weeks. However, serious sores or those that persist behind this point should be looked at.

If you have a canker sore that is particularly large, uncontrollably painful, lasts longer than three weeks, or is accompanied by a high fever, seek the attention of a healthcare provider.

Frequent canker sores may suggest that you are dealing with other health problems. For example, you may not be getting enough of certain nutrients in your diet.

You might also have a health problem that affects your immune system.

A Word From Verywell

If you have a strange sore on or around your mouth, talk to your healthcare provider or dentist. They will most likely be able to diagnose the type of sore by looking at or testing it. Then they can determine how and if the sore should be treated.

If you are uncertain what type of sore you have, it makes sense to be cautious during both intimate and casual interactions with others.

And remember, too, that some of the infections that can cause these sores may be transmitted even when sores aren't visible. Practicing safer oral sex all of the time can reduce the risk of STD transmission.

Frequently Asked Questions

  • What are common causes of mouth sores?

    There are many causes of mouth sores or lesions, some of which are contagious or non-contagious. These include:

  • Is a chancroid the same as a chancre?

    No. A chancroid is a type of skin ulcer caused by the sexually transmitted bacteria Haemophilus ducreyi. Chancroids can affect the genitals and back of the throat, but unlike chancres, are extremely painful, soft, and tend to causes multiple lesions. Chancroids are also very contagious but are rarely seen in the United States.

Was this page helpful?
9 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Institute for Quality and Efficiency in Health Care. Cold cores: overview. in: InformHealth.org [Internet]. Updated July 12, 2018.

  2. Demir FT, Salaeva K, Altunay IK, Yalcın O. An extraordinary case of syphilis presenting with a labial ulcer. Saudi Med J. 2016;37(11):1261-1264. doi:10.15537/smj.2016.11.15674

  3. Workowski KA, Bachmann LH, Chan PA, et al. Sexually transmitted infections treatment guidelines, 2021MMWR Recomm Rep. 2021;70(4):1-187. doi:10.15585/mmwr.rr7004a1

  4. Cleveland Clinic. Canker sores. Updated August 29, 2019.

  5. Plewa M, Chatterjee K. Aphthous stomatitis. StatPearls Publishing. Updated August 9, 2021.

  6. Vaillant L, Samimi M. [Aphthous ulcers and oral ulcerations]. Presse Med. 2016;45(2):215-26. doi:10.1016/j.lpm.2016.01.005

  7. Edgar NR, Saleh D, Miller RA. Recurrent aphthous stomatitis: A review. J Clin Aesthet Dermatol. 2017;10(3):26-36.

  8. MedlinePlus. Mouth disorders. Updated January 2, 2017.

  9. Centers for Disease Control and Prevention. Sexually transmitted disease surveillance 2016. September 2017.