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Skin Problems

Canker Sores

Prevention - Home Treatment - When to Call a Health Professional

Canker sores are painful, open sores that form on the inside of the mouth. Possible causes of canker sores include injury to the inside of the mouth, infection, certain foods, stress, genetic tendency to get canker sores, and female hormones. The sores usually heal in 7 to 10 days.


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  • Avoid injuring the inside of your mouth:

    • Chew food slowly and carefully.

    • Use a soft-bristle toothbrush, and brush your teeth thoroughly but gently.

  • Avoid foods that seem to cause sores.

Home Treatment

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  • Avoid coffee, spicy and salty foods, and citrus fruits when you have open sores in your mouth.

  • Apply a nonprescription canker sore medication to protect the sore, ease pain, and speed healing.

  • Rinse your mouth with a mixture of 15 ml ( 1 tbsp) of hydrogen peroxide in 240 ml ( 8 oz) of water.

  • Applying a thin paste of baking soda and water to the sore may relieve pain.

When to Call a Health Professional

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  • If mouth sores develop after you start taking a medication.

  • If a canker sore, or any sore, does not heal in 14 days.

  • If a sore is very painful or recurs frequently.

  • If white spots that are not canker sores appear in the mouth and are not improving after 1 to 2 weeks.


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