Canker sores, also medically known as aphthous
ulcers, are small ulcer craters in the lining of the mouth that are frequently
painful and sensitive. The ulcers begin as small oval or round reddish swellings
that usually burst within a day. The ruptured sores are covered by a thin white
or yellow membrane and edged by a red halo. Canker sores are usually found on
the movable parts of the mouth such as the tongue or the inside lining of the
lips and cheeks, and usually last 10 days - 2 weeks.
The cause of canker sores is not well understood.
Canker sores can be caused from a reaction of the immune system, bacterial
infections, hormonal disorders, stress, trauma, heredity, food allergies or
sensitivities (acidic foods such as pineapple), or deficiencies of iron, folic
acid, or vitamin B12.