What is burning mouth?
Burning mouth is a sensation of burning in the tongue and often of the palate (the roof of the mouth); however, it may also occur anywhere in the mouth or throat. It starts "out of the blue" for no apparent reason and persists for months or even years. The sensation is commonly described as the discomfort felt when the tongue is burned with hot coffee.
Most people find that the burning sensation gets worse through the day. The mouth may feel fine in the morning, only to develop burning in the evening. Once asleep, the pain seems to lessen. The next morning the cycle recurs.
A metallic taste or bitter taste often occurs at the same time as the burning sensation. The feeling of a dry mouth sensation is commonly reported; however, an exam of the lining of the mouth almost always reveals normal saliva flow. At times, the burning pain may be very severe and lead to depression and anxiety from the chronic pain.
What causes burning mouth?
Research has revealed that there is a relationship between burning mouth and taste (gustatory) changes. Many people with burning mouth have a loss of bitter taste buds at the tip of the tongue. So someone with normal taste for sweet, sour, and salty has a reduced sensitivity for bitter taste. The theory is that taste inhibits pain, but when the ability to taste bitter is lost, pain fibers begin to "fire" spontaneously. This pain is felt as a burning sensation in the mouth.
An infection in the mouth, a deficiency of vitamin B 12, folate, or iron can mimic the sensation of burning mouth.