A black hairy tongue is a temporary and harmless condition that is often caused by an overgrowth of bacteria in your mouth. Certain types of bacteria accumulate on the papillae (the small projections that cover the tongue) and create red blood cell pigments, which can make the tongue look black. And if the normal shedding of the outer layer of cells on the tongue is inhibited, the papillae are larger and the tongue can appear “hairy.”
No one knows for sure what causes a black hairy tongue. But some research suggests that it can be caused by a change in the normal bacteria in the mouth due to antibiotic use for a medical condition, or by using products that contain bismuth.
Other possible causes of a black hairy tongue include smoking or using other tobacco products, drinking excessive amounts of coffee or tea, and failing to follow a regular routine of daily oral hygiene.
Ironically, chronic bad breath has not been associated with a black hairy tongue, but using certain mouthwashes may increase your risk. Mouthwashes containing astringents (such as menthol or witch hazel), or full-strength oxidizing agents such as peroxide, may increase your risk of developing a black hairy tongue if you use them excessively.
Fortunately, a black hairy tongue will usually resolve if you take these simple steps:
- Brush: Gently brush your tongue with a toothbrush twice a day as part of your daily dental care routine. Once the problem is resolved, it is still a good idea to brush your tongue—you can help prevent the black tongue from coming back.
- Double Rinse: Use a dilute solution of one part hydrogen peroxide to five parts water to rinse your mouth, then rinse again with plain water.
If the discoloration persists, see your dental professional.