What Causes Canker Sores?

Canker sores are very painful sores found inside the mouth that often appear out of nowhere, leaving suffers asking: What causes canker sores?

Answer: We know what canker sores are, but the exact cause is still unknown. Women statistically suffer from canker sores more often than men. Canker sores are typically seen in people between the ages of 10 and 40, although they have been known to show up at any age.

There is reason to believe that certain types of bacteria and/or viruses are responsible for the painful mouth sores. Canker sores are not contagious and are not related to the herpes simplex virus, also known as cold sores.

Canker sores are caused by:

  • Injuries to the mouth, as seen frequently by contact sports players. Accidentally biting the inside of the cheek or lip may also result in a canker sore
  • Temperature hot food or drink may cause a canker sore in the area of the mouth that was essentially burnt by the offending substance
  • Spicy and/or acidic foods often produce a canker sore as a response to the irritation these spices and acids create in the mouth
  • The use of chewing (smokeless) tobacco will often cause a canker sore to develop in the area of the mouth where the tobacco is held, due to the irritating chemicals found in the addictive product
  • Poor-fitting, complete or partial dentures may cause canker sores in the area of the mouth where the denture may rubbing on the tissue. The development of a canker sore is often one of the first signs that indicate the need for a denture reline or adjustment by your dentist or denturist
  • Orthodontic brackets, bands, and various other orthodontic attachments will often cause canker sores to develop in area of the mouth where there is constant friction on the oral tissues. This is common when orthodontic treatment first begins and may occur after each subsequent adjustments, throughout each stage of treatment
  • Allergies to metals such as nickel may become evident in the mouth of a person wearing orthodontic devices necessary to move the teeth. Canker sores may begin to appear adjacent to the metal attachments. This is often referred to as contact dermatitis.
  • Broken teeth are often sharp and may rub on the oral tissues to produce painful canker sores. Broken restorations may also cause a similar effect on the oral tissues
  • Emotional stress has been identified as a possible trigger that may cause the development of canker sores
  • Bacteria responsible for peptic ulcers known as Helicobacter pylori, has been linked to canker sore occurrence
  • Vitamin deficiencies, specifically vitamin B12, foliate (folic acid), and iron, may trigger canker sore development
  • Hormonal changes, notably during menstruation, pregnancy, and menopause, have been linked to canker sores
  • Canker sores often run in families. Genetics may be a factor for many canker sore sufferers
  • Allergic reactions and sensitivities to certain foods may cause a canker sore to develop. Allergic reaction to certain types of bacteria found in the mouth may also result in this type of mouth ulcer
  • Celiac disease sufferers may experience canker sores. Gluten may be associated with the development of canker sores in those with celiac disease
  • Information associated with inflammatory bowel disease (IBD) often will list canker sores as a complication associated with Crohn’s disease and ulcerative colitis
  • Mouth sores are a common occurrence observed in immunosuppressed patients, such as those with HIV/AIDS
  • Behcet’s Disease, a rare autoimmune disease that damages the body’s blood vessels notes mouth sores, more specifically canker sores, as a one of the four most common symptoms of the disease
  • Sodium lauryl sulfate is a common ingredient in toothpaste and had been associated with the development of canker sores

Treatment is generally not necessary for most canker sores as they tend to heal quickly on their own. If canker sores persist for longer than 2 weeks, see the dentist.

See your dentist immediately if canker sores:

  • Become unusually larger than normal
  • Are extremely painful, interfering with eating, drinking, and talking
  • Begin to appear more frequently than normal
  • Do not heal after 14 days
  • Are accompanied by a high fever
  • Appear to become infected