A black hairy tongue is produced when the papilla (finger-like projections from the surface of the tongue) fail to fall off, as they normally do. As the length of the papilla increases, debris collects and bacteria grow, producing the characteristic dark "furry" appearance. This can be associated with antibiotic use.
Review Date 2/27/2019
Updated by: Josef Shargorodsky, MD, MPH, Johns Hopkins University School of Medicine, Baltimore, MD. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.