A discoloration of the tongue, most often called black hairy tongue, is often caused by bacteria or yeast growth. The tongue discoloration may appear in a variety of shades, including black, brown, yellow or green.
While some tongue issues like pain and swelling are often signs of more serious issues, tongue discoloration like brown tongue is often due to bacteria or yeast growth. The yeast or bacteria grows on the papillae, which cause the bumpy surface of the tongue. In ordinary situations, papillae are whitish-pink in color and shed over time. As the bacteria or yeast sticks to the papillae, they change color and grow longer than usual, which leads to the tongue having a hairy, discolored appearance.
There are many causes for brown or other discolorations of the tongue:
- Drinking coffee or tea
- Poor oral hygiene
- Radiation therapy
WebMD suggests that certain medications, such as those containing bismuth, which is found in Pepto-Bismol, as well as certain antibiotics that upset the balance of bacteria in the body, may also contribute to tongue discoloration. A condition known as glossitis is an inflammation of the surface of the tongue that may cause discoloration. Further, the use of mouthwash that contains peroxide, witch hazel or menthol may contribute to discoloration. People with HIV, intravenous drug users and men are more prone to this condition.