The precise cause of canker sores remains unclear, though researchers suspect that a combination of several factors contributes to outbreaks, even in the same person.

Possible triggers for canker sores include:

  • A minor injury to your mouth from dental work, overzealous brushing, sports mishaps, spicy or acidic foods, or an accidental cheek bite
  • Toothpastes and mouth rinses containing sodium lauryl sulfate
  • Food sensitivities, particularly to chocolate, coffee, strawberries, eggs, nuts, cheese and highly acidic foods, such as pineapple
  • A diet lacking in vitamin B-12, zinc, folate (folic acid) or iron
  • An allergic response to certain bacteria in your mouth
  • Helicobacter pylori, the same bacteria that cause peptic ulcers
  • Hormonal shifts during menstruation
  • Emotional stress

Canker sores may also occur because of certain conditions and diseases, such as:

  • Celiac disease, a serious intestinal disorder caused by a sensitivity to gluten, a protein found in most grains
  • Inflammatory bowel diseases, such as Crohn's disease and ulcerative colitis
  • Behcet's disease, a rare disorder that causes inflammation throughout the body, including the mouth
  • A faulty immune system that attacks healthy cells in your mouth instead of pathogens, such as viruses and bacteria
  • HIV/AIDS, which suppresses the immune system

Unlike cold sores, canker sores are not associated with herpes virus infections.

Mar. 24, 2012