Causes of Canker Sores

 
 Fatigue
 
 Abnormal immune response to normal bacteria in the mouth
 
 Canker sores are occasionally associated with Crohn's disease
 

Traditional Medicine Perspective

Sores arise as a discharge of waste that is not being cleansed by the liver and kidneys. Canker sores, therefore, indicate a depressed liver and kidney function. Treatment consists of strengthening both of these organs so that blood can be more efficiently cleansed and detoxified. 

See Your Medical Doctor When...
 Your sore persists for more than two weeks. This may indicate a more serious condition that needs treatment. A mouth ulcer that sticks around, even if it's not causing pain, could be the sign of oral cancer or a number of other disorders, including vitamin deficiency, anemia, or Crohn disease.
 
 You get sores once a week or more, especially when they appear in bunches.
 
 Your canker sores are extremely painful; your doctor can give you medication to alleviate pain.
 
 You have persistent multiple mouth sores, which may indicate an underlying problem, such as a drug reaction or, in rare cases, oral cancer or leukemia.