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Canker Sores


Canker sores

are small ulcers that develop inside your mouth. Ulcers are open sores that may be shallow or deep. You may have one or more sores at a time, and they may grow in clusters.

Common signs and symptoms of canker sores:

  • One or more sores on the back or floor of your mouth, the inner side of your cheeks and lips, or under your tongue
  • Round or oval-shaped red sores that may be covered with a white or yellow film
  • Pain, burning, or tingling in your mouth
  • Fever and fatigue
  • Difficulty chewing and swallowing

Seek care immediately if:

  • You cannot eat or drink because of your mouth pain.

Contact your healthcare provider if:

  • Your canker sores are not gone after 3 to 4 weeks.
  • Your pain does not go away after you take medicines.
  • Your sores are getting worse or you are getting more sores, even after treatment.
  • You have questions or concerns about your condition or care.


may not be needed. Canker sores cannot be cured. The sores may go away for a time, and then come back again. You may need pain medicine given as a cream, gel, or mouthwash. You may also need steroid medicine to decrease inflammation.

Manage your symptoms:

  • Eat soft, plain foods until your canker sores heal. Examples include yogurt, eggs, and creamy soups. You may need to change some foods you usually eat. Do not have crunchy, dry, or salty foods, such as dry toast, popcorn, or chips. These can cause pain. Do not have foods or drinks that contain citric acid, such as grapefruit, orange juice, lemons, and limes. These may make your pain worse or cause more sores to form.
  • Care for your mouth as directed. Gently brush your teeth and tongue every day. Use a soft toothbrush. If you have dentures, clean them every day. If your braces or dentures do not feel comfortable, have a dentist check them to see that they fit well.

Follow up with your doctor as directed:

Write down your questions so you remember to ask them during your visits.

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The above information is an educational aid only. It is not intended as medical advice for individual conditions or treatments. Talk to your doctor, nurse or pharmacist before following any medical regimen to see if it is safe and effective for you.

Learn more about Canker Sores (Ambulatory Care)

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Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.