Black hairy tongue is a temporary, harmless oral condition that gives the tongue a dark, furry appearance. The distinct look usually results from a buildup of dead skin cells on the many tiny projections (papillae) on the surface of the tongue that contain taste buds. These papillae, which are longer than normal, can easily trap and be stained by bacteria, yeast, tobacco, food or other substances.
Although black hairy tongue may look alarming, typically it doesn't cause any health problems, and it's usually painless. Black hairy tongue usually resolves by eliminating possible causes or contributing factors and practicing good oral hygiene.