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Canker Sores


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 are the different types of canker sores?

  • Minor: Minor canker sores are usually less than ½ inch in size. They heal 10 to 14 days after you get them. After they heal, they do not leave a scar.
  • Major: Major canker sores are usually larger than ½ inch in size. They take more than 2 weeks to heal, and can leave a scar.
  • Herpetiform: This is a cluster of 10 to 100 sores. Up to 100 smaller sores can join together and create a larger sore. While smaller sores can heal in a week, they may leave scars. Larger sores are deep and may take up to 30 days to heal.

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 for canker sores:

  • Medical conditions 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, and 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
  • Fever and fatigue
  • Difficulty chewing and swallowing

How are canker sores diagnosed?

Your caregiver will ask about your medical history. Tell him about the medicines you are taking. He will ask if you have had canker sores before. Tell him if any of your family members have had them. Your caregiver will examine the inside of your mouth.

How are canker sores treated?

There is no cure for canker sores. The sores may go away for a time, and then come back again. You may need any of the following medicines:

  • Pain medicine: This may be given to decrease pain in your mouth. This medicine may be given as a cream, gel, or mouthwash.
  • Steroid medicine: This may be given to decrease redness, swelling, and pain.
  • Supplements: Ask your caregiver if you should have more of certain vitamins and minerals to help prevent canker sores.

How can I manage my symptoms?

  • Change the foods you eat: Avoid crunchy, dry, and salty foods such as dry toast, popcorn, and chips because they can cause pain. Avoid foods and drinks that contain citric acid such as grapefruit, orange juice, lemons, and limes. These foods may make your pain worse or cause more sores to form. Eat soft, plain foods until your canker sores heal.
  • Care for your mouth: 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.

When should I contact my caregiver?

Contact your caregiver if:

  • You have chills or a fever.
  • 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.

When should I seek care immediate care?

Seek care immediately or call 911 if:

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

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 caregivers 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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