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Canker Sores

What causes canker sores?

The cause of most canker sores is not well understood, and multiple factors may cause sores to appear. Some possible causes of canker sores include the following:

  • Injury to the mouth may cause simple canker sores. Injury could be from vigorous tooth brushing, dental work, braces or dentures, or a sports accident.
  • Acidic foods, including citrus fruits, may trigger a canker sore or make it worse.
  • Food sensitivities or allergies (anything from highly acidic foods to chocolate and coffee)
  • Diets low in vitamins B12, zinc, folate (folic acid), or iron
  • Toothpaste containing sodium lauryl sulfate
  • Allergy to certain bacteria in the mouth
  • Hormones
  • Emotional stress
  • Smoking
  • Gastrointestinal tract diseases such as Celiac disease or Crohn's disease
  • Autoimmune disorders such as systemic lupus erythematosus or Behçet's disease
  • Other immune system weakness such as a cold or the flu, HIV/AIDS, or an organ transplan
  • Systemic conditions such as Crohn’s disease or nutritional deficiencie
  • Oral cancer
  • Certain drugs may cause canker sores, including:
    • Aspirin
    • Nonsteroidal anti-inflammatory drugs (NSAIDs)
    • Beta-blockers
    • Oral nicotine
    • Chemotherapy medicines
    • Immunosuppressants
    • Penicillamine
    • Sulfa drugs
    • Phenytoin
    • Anticholinergic bronchodilators
    • Platelet aggregation inhibitors
    • Vasodilators
    • Protease inhibitors
    • Antibiotics
    • Antiretrovirals
    • Antihypertensives
Reviewed on 10/10/2016
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