Authored by Revere Health

Canker Sore 101

July 20, 2018 | Family Medicine

Canker sores can be miserable for those who deal with them, even though they usually go away within a week or two. Canker sores (also referred to as aphthous ulcers) are shallow, painful, small sores in the mouth. They are not contagious and are different than cold sores because they are usually inside the mouth rather than on the lips.

Common Causes of Canker Sores

One reason that canker sores are hard to treat is the exact cause is unknown. It’s different for every person, although some common culprits may include:

  • Tissue injury
  • Stress
  • Acidic or citrus foods like oranges, lemons, apples, pineapples, strawberries, tomatoes and figs
  • Dental appliances or sharp teeth
  • Underlying health conditions like a worn down immune system
  • Nutritional deficiencies in things such as iron, folic acid, zinc and vitamin B-12
  • Gastrointestinal diseases such as Crohn’s disease and celiac disease
  • Mouth rinse and toothpaste containing sodium lauryl sulfate
  • Allergic response to mouth bacteria
  • Hormonal changes during menstruation

Because it is hard to pinpoint exactly what causes canker sores, it can also be difficult to treat them or to determine what the patient should do to prevent them. Teens and young adults are more likely to get canker sores, and women are more likely than men to get them. There is also a genetic component to the prevalence of canker sores, but it could be explained by a shared exposure to allergens, food and other environmental factors.

Types of Canker Sores

Canker sores form inside your lips or cheeks, under your tongue, on your soft palate or at the base of the gums. Many notice a burning or tingling sensation several days before the sore appears. There are three types of canker sores:

  • Minor: red edge around an oval shape, smaller and heal within one to two weeks without scarring
  • Major: deeper and larger, irregular edges in larger sores, extremely painful, may leave scarring and can take four to six weeks to heal
  • Herpetiform: appear in clusters of many small, pinpoint-sized sores, irregular edges and will heal within one to two weeks without scarring

Most sores have a white or gray color to them and are round. They will also have a red border or edge, and in severe cases, you may also run a fever, have swollen lymph nodes or feel sluggish throughout the day.

Treating and Preventing Canker Sores

Many canker sores go away without treatment, although there are topical treatments to numb the pain. If you have constant canker sores for several weeks, they may be caused by an underlying issue that your doctor or dentist should attend to. You can help prevent canker sores by:

  • Choosing healthy foods like whole grains, vegetables and fruits
  • Avoiding foods that irritate your mouth, including any that you are allergic or sensitive to
  • Brushing and flossing every day
  • Avoiding mouthwash and toothpaste with sodium lauryl sulfate
  • Protecting your mouth from dental appliances and braces
  • Reducing your stress levels with stress-reduction techniques

Although canker sores are common and there is no definite treatment for them, we encourage you to see a doctor if canker sores cause severe pain or if you have constant canker sores.


Revere Health Orem Family Medicine is devoted to comprehensive healthcare for patients of all ages, and committed to provide thorough and timely health care for the entire family throughout all stages of life.



”Canker Sore.” Mayo Clinic.

“Dental Health and Canker Sores.” WebMD.

The Live Better Team


The Live Better Team

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This information is not intended to replace the advice of a medical professional. You should always consult your doctor before making decisions about your health.