Canker sores in the mouth are caused by a combination of factors, though the exact cause is not fully understood. Common triggers and contributing causes include:
- Minor injuries to the mouth such as from dental work, aggressive brushing, accidental cheek bites, or sports mishaps
- Sensitivity or allergic reactions to certain foods like chocolate, coffee, strawberries, eggs, nuts, cheese, spicy or acidic foods (e.g., citrus fruits, tomatoes)
- Toothpastes and mouth rinses containing sodium lauryl sulfate (SLS), which can irritate the mouth lining
- Nutritional deficiencies, particularly low levels of vitamin B12, zinc, folic acid, or iron
- Emotional stress and anxiety, which can trigger outbreaks
- Hormonal changes, especially during menstruation
- A weakened immune system or immune system dysfunction
- Certain medical conditions such as celiac disease, inflammatory bowel diseases (Crohn's disease, ulcerative colitis), Behçet's disease, HIV/AIDS, and lupus
- Infection with Helicobacter pylori bacteria, which also causes peptic ulcers
Canker sores are not caused by herpes virus and are not contagious. They usually heal on their own within one to two weeks without scarring
. In summary, canker sores result from a mix of physical injury, immune response, nutritional factors, stress, and sensitivities to foods or oral care products. Avoiding known triggers and maintaining good oral hygiene can help reduce their occurrence
