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Home > Services > Dentistry > Dental Conditions > Aphthous Ulcers (Canker Sores)

Aphthous Ulcers (Canker Sores)

Aphthous ulcers, also known as canker sores, are painful, temporary sores that may occur anywhere in the mouth. They may appear one at a time or as a group. Although canker sores are not serious, other mouth sores may be.

canker sores

Canker Sores in the Mouth
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The cause of of canker sores is unknown. They're thought to be a result from an overreaction of the immune system.

Canker sores are not a form of the herpes virus. Unlike herpes, canker sores cannot spread from one person to another.

Risk Factors

Canker sores tend to occur more often in women than in men.

The following may increase your chance of a canker sore:

  • Stress or trauma in the mouth, such as biting the tongue, trauma from falls or toothbrushes
  • Certain foods, especially acidic foods, such as tomatoes and pineapples
  • Changes in hormone levels

Canker sores vary in size, and they typically occur on the lips, tongue and the inner surface of the cheeks. Sores are open, shallow grayish tones, that may be slightly raised with a yellowish-white border surrounded by a red border.

Some people get canker sores two or three times per year. Others develop sores continually one after another.


Your doctor will ask about your symptoms, medical history, and will perform a physical exam. To rule out other medical problems your doctor may do the following:

  • Biopsy — a small sample of the sore will be sent to a lab for closer examination
  • Blood culture or tests — to look for signs of an infection or other systemic health conditions

It's especially important to examine mouth sores that do not heal within two weeks. They may be a sign of cancer.

Treating Canker Sores

Canker sores usually heal on their own within 1-2 weeks, and treatment is not necessary. If your canker sore is especially painful or is taking a long time to heal, your doctor may recommend the following:

Oral Pain-Relieving Rinses or Gels

You may use an oral rinse every three hours or before meals. This provides short-term relief from pain. Additionally, you can apply anti-pain oral gel directly on the sores about four times per day to numb the area. Prescriptions are not needed for these products.

Oral Antibiotic Rinse

Your doctor may prescribe a liquid antibiotic for multiple sores. You can use this four times daily for 10 days. The liquid coats the ulcers and prevents new sores from forming. Sometimes, this treatment can cause an oral infection called thrush, which can be easily treated.


Your doctor may recommend a liquid, oral rinse steroid for severe outbreaks. Steroids help reduce swelling in the mouth caused by severe sores.

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Content was created using EBSCO’s Health Library. Edits to original content made by Rector and Visitors of the University of Virginia. This information is not a substitute for professional medical advice.

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