Hesperian Health Guides

Canker Sores

In this chapter:

The exact cause of canker sores is not known. Canker sores affect both adults and children, and are very common among youth. One or more sores can appear at any time. These sores hurt, especially when pieces of food touch them.

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Signs:
  • A sore can appear on the cheeks, inside the lips, on the tongue, or below the gums on the smooth skin.
  • The sore is white or yellow with the skin around it bright red.
  • The person may have had a similar kind of sore before. It tends to come back.

Note: a sharp edge of a denture rubbing against the gums can make a similar kind of sore.

Treatment:

A canker sore should go away by itself after about 3 weeks. Medicine will not make this happen faster. However, if the sore is caused by something like a broken tooth or the sharp edge of a denture, smoothing the tooth or denture will help. To feel more comfortable while the sore heals, a person can:

  • Eat foods that are soft and not likely to hurt the sore.
  • Do not eat spicy food.
  • Drink lots of water.
  • Chew food on the other side of the mouth, away from the sore.


A denture which does not fit should be remade.

In the meantime, leave the denture out of the mouth for 2 or 3 days.

Ask the person to rinse with warm salt water, 4 cups each day until the sore is better.
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If the sore continues for longer than 3 weeks, it may be a different or more serious medical condition. See a doctor as soon as possible..

A sore that does not heal after antibiotic treatment may be cancer. See a doctor immediately.


This page was updated:17 May 2024