[header] How to treat thrush [title] Know what causes thrush. [step] Thrush, or oral candidiasis, is caused by an overgrowth of a type of fungus, or yeast, called candida albicans. Candida is a normal part of the body. 
[substeps] Candida albicans is naturally found throughout the gastrointestinal tract, including the mouth. Candida is also a normal resident of the skin.