Mouth thrush is a form of yeast infection that takes place in the oral cavity and on the tongue. It is also known as oral candidiasis because it is caused by candida overgrowth.
Candida is a natural yeast that lives in small quantities in the mouth and does not normally cause problems. When it multiplies too much it can become problematic and cause a white coating on the tongue, esophagus, throat, or the walls of the mouth. This condition is mainly seen with newborn children or toddlers. Oral thrush is a relatively mild condition that can disappear as soon as treatment begins. This of course assumes that it is diagnosed quickly and treatment is started early. It is uncommon for adults to suffer from this unless the immune system has been weakened by some other condition which is affecting the body.