Here is a potion of the article on the Mayo Clinic website:
The precise cause of canker sores remains unclear, though researchers suspect that a combination of 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 or an accidental cheek bite Toothpastes and mouth rinses containing sodium lauryl sulfate Food sensitivities, particularly to chocolate, coffee, strawberries, eggs, nuts, cheese, and spicy or acidic foods 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. Risk factors
Anyone can develop canker sores. But they occur more often in teens and young adults, and they're more common in females.
Often people with recurrent canker sores have a family history of the disorder. This may be due to heredity or to a shared factor in the environment, such as certain foods or allergens. Prevention
Canker sores often recur, but you may be able to reduce their frequency by following these tips:
Watch what you eat. Try to avoid foods that seem to irritate your mouth. These may include nuts, chips, pretzels, certain spices, salty foods and acidic fruits, such as pineapple, grapefruit and oranges. Avoid any foods to which you're sensitive or allergic. Choose healthy foods. To help prevent nutritional deficiencies, eat plenty of fruits, vegetables and whole grains. Follow good oral hygiene habits. Regular brushing after meals and flossing once a day can keep your mouth clean and free of foods that might trigger a sore. Use a soft brush to help prevent irritation to delicate mouth tissues, and avoid toothpastes and mouth rinses that contain sodium lauryl sulfate. Protect your mouth. If you have braces or other dental appliances, ask your dentist about orthodontic waxes to cover sharp edges. Reduce your stress. If your canker sores seem to be related to stress, learn and use stress-reduction techniques, such as meditation and guided imagery.