A Guide to Canker Sores: Causes, Symptoms, & Treatments


According to the American Academy of Oral Medicine, more than half of the population of the United States has experienced a canker sore at some time. While they are not contagious, they can be painful and recur in the same or new location after a period of time. In some cases, canker sores can even affect your ability to speak, eat, or swallow. Keep reading to learn more about signs and causes of canker sores. 

Symptoms and Signs of Canker Sores

Canker sores are the most common type of oral lesion and should not be confused with cold sores, which are caused by the herpes simplex virus. They usually start with a burning or tingling feeling before progressing into a round or oval lesion, which contains a white or yellow center and a red border. Unlike cold sores, canker sores are not contagious and appear in three forms: minor, major, and herpetiform. 

Minor canker sores

  • Are relatively small
  • Are oval shaped with a red border
  • Affect more than 80% of canker sore sufferers
  • Heal without scarring in one to two weeks

Major canker sores

  • Are larger and deeper than minor canker sores
  • Often very painful
  • Affect approximately 15% of patients with canker sores
  • Can take up to six weeks to heal and leave extensive scarring

Herpetiform canker sores

  • Are pinpoint size
  • Often appear in clusters of 10 to 100 sores
  • Occur in less than 5% of canker sore sufferers
  • Heal without scarring in one to two weeks

Difference Between Canker Sores and Cold Sores

Canker sores and cold sores are not the same. Canker sores only occur in the inside of your mouth, cannot be transmitted, are not caused by the herpes virus, and appear as crater-like ulcers with a white or yellow center. Cold sores form on and around your lips, can be transmitted, are caused by the herpes virus, and are filled with a clear fluid that often crusts over and forms a scab before resolving.

What Causes Canker Sores? 

Canker sores can be triggered by a number of things, including a weak immune system, stress, and medication. Although any person can develop canker sores, they are most common in females, teens and young adults. People who experience recurring canker sores may also have a family history of the disorder. While the direct cause of canker sores remains unclear, possible causes of canker sores include:

  • Injuries to mouth
  • Emotional stress
  • Food sensitivities or allergies
  • Lack of vitamins and minerals in diet, including vitamin B-12, zinc, folate, or iron
  • Hormonal shifts
  • Immune diseases, including HIV, lupus, inflammatory bowel disease, and celiac

Most Common Sites for Canker Sores

Canker sores are small lesions that develop in the soft tissues in your mouth or at the base of your gums. Areas where canker sores may form include:

  • Tongue
  • Inside Cheeks
  • Inside Lips
  • Base of Gums
  • Roof of Mouth

How to Prevent and Treat Canker Sores

To reduce your risk of recurring canker sores, follow a healthy diet, practice good oral hygiene habits, reduce your stress levels, and protect your mouth from cuts, bruises, and other injuries. If you are currently dealing with a canker sore, try the following remedies at home to relieve your symptoms:

  • Eat soft, bland foods
  • Avoid acidic foods
  • Use a soft toothbrush to prevent irritation
  • Rinse with saltwater or antimicrobial mouthwash
  • Use over-the-counter canker sore medicine or pain reliever

When to See a Doctor

There is no need to see a doctor or dentist for minor canker sores, which heal on their own. However, you should schedule an appointment with your dentist if your canker sore is persistent, painful, or recurring. Major cold sores may require additional medical care. Consult your doctor if you experience any of the following symptoms:

  • Unusually large canker sores
  • Recurring canker sores
  • Persistent sores, lasting two or more weeks
  • Painful sores
  • Difficulty eating or drinking
  • Sores near sharp tooth surface or dental appliances

Final Word

Anyone can develop canker sores, but that doesn’t mean you should have to deal with them on your own. To protect your mouth from recurring canker sores, schedule an appointment with your dentist. He or she will be able to diagnose your canker sores based on their appearance and recommend treatment for your specific case. For a quick assessment of your oral health, we recommend our Dental Hygiene Quiz. To schedule your consultation with one of our experienced dentists, please contact your local Gentle Dental office today.