Canker sores are small, shallow ulcers that develop on the soft tissue inside the mouth or the gums. Unlike cold sores, canker sores are not contagious and do not grow on the outside of the mouth or the lips. There are many causes, from stress to food sensitivities. While most go away on their own in a week or two, the sores can be incredibly painful and make it difficult to speak and eat.

Overzealous Brushing

According to many dentists, if the bristles of the toothbrush bend while one is brushing, he or she is pressing too hard. The gums and soft tissue of the mouth are sensitive. Vigorous brushing can cause small tears or inflammation in the tissues. These minor injuries are the most common precursors to canker sores. When brushing, apply only enough pressure to feel the bristles lightly against the mouth. A person with a canker sore should not stop brushing but should take care to be gentle around the abrasion.

Food Sensitivities

Food sensitivities and allergies are abundant in today’s world. Serious allergies can lead to anaphylactic shock, but milder symptoms include an itchy throat and canker sores. Chocolate, coffee, strawberries, eggs, nuts, citrus fruits, tomatoes, and cheese are some of the more common culprits of canker sores in people sensitive to these foods. Soda, which contains high amounts of corn syrup and phosphoric acid, can also cause inflammation and canker sores.

Vitamin Deficiency

Children are one of the groups most prone to canker sores because they are at higher risk of not receiving the recommended daily allowance of vitamins and minerals. That being said, adults who develop canker sores repeatedly should also investigate their vitamin intake. A deficit of B12, zinc, folate (folic acid), calcium, or iron could be a contributing factor.

Celiac Disease

Celiac disease is an autoimmune disorder characterized by extreme gluten intolerance; consumption of this protein damages the small intestine. The condition may result in bloating, abdominal pain, diarrhea, vomiting, constipation, weight loss, and fatigue. In one study, five percent of people with recurring canker sores were found to have celiac disease. This suggests that for people with the disorder, the ingestion of even small amounts of gluten may lead to canker sores. Occasionally, recurrent canker sores are the only symptom of celiac disease.

Toothpaste and Mouthwash

Many kinds of toothpaste and mouth rinses contain sodium lauryl sulfate or SLS, an additive that creates that popular foaming action. Because SLS is a soft tissue irritant, it may contribute to canker sores. Anyone dealing with chronic sores may want to select dental hygiene products free of sodium lauryl sulfate.

Dental Work or Braces

Minor injury to the mouth after dental work or routine cleaning is a common occurrence. Typically, the mouth heals itself, but excess bacteria or loose wiring from braces can aggravate, resulting in canker sores. These sores should go away within two weeks, but if they last longer or are incredibly painful, it is best to speak to a doctor.

Acidic Foods

While some foods, such as chocolate or strawberries, may cause canker sores, other foods can worsen the symptoms. Doctors believe acidic foods such as citrus fruits do not cause sores but can exacerbate the issue once they develop. Avoid foods such as lemons, pineapples, oranges, figs, and tomatoes when dealing with cuts or ulcers in the mouth.

Helicobacter Pylori

Helicobacter pylori or H. pylori is a type of bacteria common in the stomach or upper lining of the small intestines of about two-thirds of people. Most individuals with H. pylori experience no symptoms or negative health effects, but some develop ulcers or infections. Research shows H. pylori also contribute to canker sores; treating the infection may reduce their frequency.

Emotional Stress

One of the more mysterious sources of canker sores is emotional stress. While doctors are unsure about why exactly stress precipitates canker sores, there seems to be a strong link. One theory is that stress or anxiety causes people to bite their cheeks out of nervousness, resulting in minor abrasions. Another is that stress results in fatigue and a weakened immune system, leaving the body more susceptible to attacks from bacteria.

Hormonal Shifts

During menstruation, women experience various hormonal shifts. Hormones are responsible for the blood supply to gum tissue, as well as the body’s reaction to toxins and bacteria in the mouth. Thus, women may be more susceptible to oral problems — such as canker sores, bleeding gums, and swollen salivary glands — during menstruation. Also, the mucosal lining of a woman’s oral cavity is increased during menstruation, making the mouth more prone to injury and canker sores.