Oral yeast infections are quite a common occurrence among both men and women of all ages. Like other yeast infections, oral yeast infections are also primarily caused by the fungus Candida albicans, which is a naturally found microorganism in the human body. This Candida albicans lives in the mucous membranes of the body including the mouth, intestines and vagina. Due to certain imbalances in the body, this fungus multiplies indiscriminately and quite literally takes over various systems in the body. One of the effects of this is an oral yeast infection.