Mouth Sores – Definitions, Causes and Treatments

Mouth sores—if you have had them, you know just how painful and irritating they can be. They often seem to appear without a cause, and how to get rid of them is often equally mysterious. We have summarized several American Dental Association (ADA) online articles for you in hopes that we can eliminate some of the mystery behind your bothersome mouth sores and give you a better idea about what you can do about them.

There are a variety of different mouth sores that can have a number of causes. The ADA article entitled, “Mouth Sores,” lists canker sores, cold sores, oral thrush and leukoplakia as the possible different types of mouth sores. The same article lists the following as potential causes for these sores:

  • Infections from bacteria, viruses or fungus
  • Irritation from a loose orthodontic wire, a denture that doesn’t fit, or a sharp edge from a broken tooth or filling
  • The symptom of a disease or disorder

Canker Sores

The ADA article, “Canker Sores,” provides helpful information on the definition, causes and treatments for canker sores.

Canker sores are non-contagious sores inside the mouth that appear as small, white or gray sores with a red border. One or several can appear at a time.

While their exact cause is uncertain, some experts believe that possible causes for canker sores are immune system problems, bacteria or viruses. Trauma to the mouth’s soft tissue can also cause a canker sore. 

Canker sores usually heal on their own after one or two weeks. To aid the healing process, avoid hot, spicy or acidic foods that can irritate the sore. Temporary relief may be obtained by over-the-counter, topical anesthetics and antimicrobial mouthwashes. Antibiotics and some oral bandages may also reduce secondary infection.

Cold Sores

Another ADA article, “Cold Sores,” has provided the below information.

Cold sores, (also called fever blisters), are groups of fluid-filled blisters that often erupt around the lips and sometimes under the nose or around the chin.

Cold sores are very contagious and are caused by the herpes simplex virus type 1. The initial infection (primary herpes) may be confused with a cold or flu.  Once a person is infected with primary herpes, the virus stays in the body and can cause occasional attacks.

While cold sore blisters usually heal in a week by themselves, over-the-counter topical anesthetics can provide some relief. Antiviral drugs can also help to reduce the infection.


Below is a summary of the ADA article entitled, “Thrush” as it relates to its definition, causes and treatments. 

Thrush (also called Candidiasis or moniliasis) is a fungal infection that occurs when the yeast Candida albicans reproduces in large numbers. It is common among denture wearers.

Thrush most often occurs in people with weak immune systems—the very young, elderly or those debilitated by disease, such as diabetes or leukemia. Candida may also flourish after antibiotic treatment, which can decrease normal bacteria in the mouth. Finally, people with dry mouth syndrome are also susceptible to candidiasis.

Good oral hygiene is paramount. This necessitates that you clean your dentures to remove the Candida and that you remove your dentures before going to bed.  If dry mouth is the culprit, saliva substitutes and prescription medications may help when you are unable to identify the underlying cause of your dry mouth.


The final ADA article, “Leukoplakia” provides information on these less familiar type of mouth sores.

Leukoplakia are thick, whitish-color patches that form on the inside of the cheeks, gums or tongue. It is common among tobacco users.

Patches of leukoplakia are caused by cell growth. This can be the result of ill-fitting dentures or habitually chewing the inside of the cheek. Sometimes leukoplakia is associated with oral cancer, in which case a biopsy can be taken if the patch appears threatening.

Your dentist can perform regular examinations of the lesion and any necessary biopsy results. It is also important to remove any factors that might contribute to the lesion, such as quitting tobacco or replacing ill-fitting dentures or bridges.

It is our hope that our summary of the above ADA articles have helped uncover some of the mystery surrounding mouth sores. As has been made evident, there are varieties of mouth sores, and varieties of causes and treatments for them. Understanding what type of mouth sores you have, as well as how to specifically treat them is important not only for your comfort, but possibly for your long-term health as well. If you have any concerns at all about your mouth sores, please visit your dentist to receive professional diagnosis and guidance.


“Mouth Sores” –

“Canker Sores” –

“Cold Sores” –

“Thrush” –

“Leukoplakia” –