Hairy tongue is a medical condition where ... smoking, alcohol, stains from food and drink, use of chlorhexidine mouthwash (e.g. Corsodyl) may cause staining of the papillae.

Having a black fur-like substance on top of your tongue can be due to poor oral hygiene, smoking, alcohol, stains from food and drink and using chlorhexidine mouthwash. If it looks like your mouth ...

Chlorhexidine gluconate 0.12% ... may cause increased supra- or subgingival calculus). May stain rough surfaces or margins of anterior facial restorations. Pregnancy (Category B).