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Canker Sores

Medically reviewed by Last updated on Jul 4, 2022.

What are 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.

What increases my risk for canker sores?

The cause of canker sores is not known. You may have a greater risk for canker sores if your family members get them. Any of the following may increase your risk:

  • A medical condition such as cancer, celiac disease, or HIV
  • Changes in hormones that happen with a woman's monthly period
  • Sensitivity to foods such as chocolate, nuts, strawberries, or gluten (found in oats, wheat, and barley)
  • Mouth injuries caused by biting, dentures, braces, or brushing your teeth too hard
  • Medicines such as aspirin, ibuprofen, and some blood pressure medicines
  • Low levels of iron, zinc, vitamin B, or folic acid
  • Stress or anxiety

What are the 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
  • Difficulty chewing and swallowing

How are canker sores diagnosed?

Your healthcare provider will examine the inside of your mouth. The healthcare provider will ask about your medical history and if anyone in your family has canker sores. Tell the provider about the medicines you are taking and if you have had canker sores before.

How can I manage my symptoms?

Canker sores cannot be cured. The sores may go away for a time, and then come back again. The following can help manage your symptoms while you heal:

  • Medicines may be given to relieve pain or to decrease inflammation.
  • 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 every day 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.

Treatment options

The following list of medications are in some way related to or used in the treatment of this condition.

View more treatment options

When should I seek immediate care?

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

When should I contact my healthcare provider?

  • 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.

Care Agreement

You have the right to help plan your care. Learn about your health condition and how it may be treated. Discuss treatment options with your healthcare providers to decide what care you want to receive. You always have the right to refuse treatment. 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.

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