Why Do I Keep Getting Canker Sores in My Mouth: Causes and Solutions

Frequent canker sores can be triggered by stress, injury, food sensitivities, or vitamin deficiencies. See a doctor if they are large or persistent.

Common triggers

• Stress.
• Mouth injury or braces.
• Food sensitivities: citrus, spicy food, nuts, chocolate.
• Vitamin B12, iron or folate deficiency.
• Toothpaste with sodium lauryl sulfate.
• Hormonal changes.
• Celiac disease or IBD.

Facts

About 20% of people get them.

Treatment

Salt rinse, OTC gels (benzocaine), prescription rinses.

See a doctor

If sores last over 3 weeks, are very large or come with fever.

Triggers backed by studies

Recurrent aphthous stomatitis affects roughly 20 percent of the general population at some point, and up to 25 percent get repeated episodes. Minor ulcers measure under 1 cm and heal in 7 to 14 days without scarring. Major ulcers exceed 1 cm, can last weeks and may scar. Herpetiform ulcers appear in clusters of 10 to 100 tiny sores.

• Deficiencies of iron, vitamin B12, folate and zinc are found more often in people with frequent sores, so a blood test is a reasonable step.
• Sodium lauryl sulfate in some toothpastes has been linked to more frequent ulcers in small trials.
• Celiac disease, Crohn disease and Behcet disease can show up first as recurring mouth ulcers.
• Acidic foods, sharp chips and accidental biting often start a sore.

Treatments that are used

Topical corticosteroid gels, such as triamcinolone in dental paste, shorten healing time. Benzocaine gels numb pain. A 2020 review found that rinsing with a dexamethasone solution can help in severe cases. See a doctor if a sore lasts more than three weeks, since persistent ulcers can be a sign of oral cancer.

Triggers and treatment

Canker sores (aphthous ulcers) affect about 20 percent of people at some point, according to the Mayo Clinic. Triggers include minor mouth injury, acidic foods, stress, hormonal changes, and deficiencies of iron, folate, vitamin B12 or zinc. Sodium lauryl sulfate in toothpaste may trigger them in some people.

Care

Most heal in 1 to 2 weeks. Topical products with benzocaine, rinses with corticosteroids and saltwater rinses may ease pain. See a doctor if sores are larger than 1 cm, last more than 3 weeks, are very frequent, or come with fever. Frequent ulcers may be linked to celiac disease or Behcet disease.

Risk factors and associations

Studies suggest about 20 to 40 percent of people with recurrent canker sores have a family history. Associations include celiac disease, Crohn’s disease, ulcerative colitis, Behcet’s disease, HIV, nutritional deficiencies and hormonal changes. Women report more ulcers around menstruation. Stopping smoking can unexpectedly trigger sores in some people.

Home management

Avoid spicy, salty and acidic foods during healing, use a soft toothbrush, and consider toothpaste free of sodium lauryl sulfate. Over the counter options include benzocaine gels and protective pastes. A dentist or doctor may prescribe dexamethasone rinse, triamcinolone paste or oral colchicine for severe cases. B12 supplements reduced outbreaks in a 2017 trial of people with recurrent ulcers.

Based on data from the Mayo Clinic and the American Academy of Oral Medicine