CausesBy Mayo Clinic staff
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.
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