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Canker Sores: Symptoms & Treatment

Instructor: Artem Cheprasov

Artem has a doctor of veterinary medicine degree.

Do you think you have a canker sore? Compare this lesson's outline of the signs and symptoms of canker sores with what you might have and then consult a doctor.

What is a Canker Sore?

Have you ever had a small, painful sore inside of your mouth that seemed to disappear after a week or two and then came back a few days to a few months later? That may have been a canker sore, an ulcer (defect or sore) in the mouth that is whitish in color with a reddish-border. If you've had one before, you may already know the signs and symptoms related to it. For those of you who haven't had one, read below to find what these symptoms are and how canker sores are treated.

Canker Sore Signs & Symptoms

1-2 days before a canker sore appears, a person may experience a pricking or burning sensation or even some pain. Once the sore appears, it never blisters, unlike a cold sore. The pain associated with a canker sore can be severe, especially if the canker sore is large. This pain typically lasts 3-7 days and the sore usually disappears within 7-10 days. However, exceptions apply, especially for large sores that can last for months at a time.

As a reminder, canker sores occur only inside the mouth. They are more typically found on the:

  • Inside of the lip
  • Inner surface of the cheek
  • Tongue
  • Floor of the mouth
  • Soft palate
  • Throat

Generally speaking, when looking at a canker sore, you'll see that it is:

  • A shallow sore
  • Oval to round in shape, although large sores can have irregular shapes to them
  • Has a white-yellow or yellow-gray center
  • Is surrounded by a well-defined red border
  • Is typically small, less than 0.5 inches in diameter
  • May be found alone or in a cluster of several sores
  • Doesn't leave a scar once it heals, unless the sore was large

Note the shape and color of this canker sore and compare it to the description given in the lesson.
Canker sore

Canker Sore Treatment

Small canker sores usually do not require any treatment as they just go away on their own. However, large canker sores may need treatment as they are extremely painful and can stick around for a very long time (weeks to months). However, if the sores (even if small) are caused by an underlying problem like Crohn's disease, the doctor will need to treat the underlying disorder.

Barring that, other treatments for canker sores include:

  • Mouth rinses, such as ones that contain a steroid called dexamethasone. Steroids like dexamethasone help relieve the pain associated with the inflammation that underlies canker sores. It also reduces the other signs and symptoms of inflammation such as redness and swelling.
  • Topical products, like gels, that may contain pain relievers such as benzocaine
  • Oral steroids, like prednisone, if the topical ones do not seem to help much
  • Antiseptic mouth washes, ones that kill many microorganisms inside of the mouth. These may include mouthwashes that have an ingredient called chlorhexidine.
  • Antibiotics, drugs that kill bacteria, such as tetracycline
  • Immune system modulators, like cyclosporine. These help suppress some aspects of inflammation.
  • Chemical compounds, like debacterol, which chemically cauterize the canker sore.
  • Supplements, like zinc or vitamin B-6, deficiencies of which have been implicated in causing canker sores

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