Black, hairy tongue

A black, coated tongue is a temporary, harmless condition typically resulting from an overgrowth of bacteria and sometimes yeast in the mouth. These organisms accumulate on the tiny projections of the tongue — called papillae — and cause discoloration. Certain types of bacteria and yeast make red blood cell pigments (porphyrins), which can give the tongue a black appearance. In some cases, the tongue may also appear "hairy" due to more rapid growth of papillae or an interruption of the normal shedding of cells by the tongue.