Canker sores (aphthous stomatitis) are ulcerations of the mouth and lips. Hidden food sensitivities are usually involved. Although almost any food could be a culprit (depending on biochemical individuality), the most common offenders tend to be milk, cheese, wheat, tomato, vinegar, lemon, pineapple and mustard. [Further reading: One's Food is Another's Poison.]
Underlying Theme: Allergies