(HealthDay News) - Canker sores are painful ulcers inside the mouth that most often occur on the base of the gums, inside the cheeks or lips, on the soft palate, or on the tongue. They typically do not require treatment and go away on their own.

Certain risk factors can increase the likelihood of developing canker sores. Here's a list, courtesy of the U.S. National Library of Medicine:

  • Family history of canker sores.
  • Weakened immune system.
  • Dental work.
  • Biting the inside of the cheek or the tongue.
  • Stress, anxiety or changes in hormone levels.
  • Malnutrition, particularly deficiencies in iron, folic acid or vitamin B-12.
  • Allergic reaction to food.
  • Viral infection.