Mouth allergy is suspected in canker sores

What causes canker sores (aphthous ulcers)? What are the risk factors for triggering outbreaks of these mouth ulcers? Canker sores are a type of mouth ulcer. In fact, they are the most common type of recurring mouth ulceration. The cause of canker sores is not well understood. Their formation, however, is thought to be related to an abnormal response by the sufferer's immune system.
Allergies to foods and other substances have been postulated as being triggers for canker sore breakouts. Any substance that comes into contact with the person's oral tissues must be considered to be a potential causative agent. If an mouth allergy is suspected the individual might choose to maintain a diary so to help them (and their dentist) identify the most likely candidates associated with the causation of their sores. In some cases allergy testing might be considered.