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 - Inflam