The tongue's papillae (tiny, rounded projections) may become discolored if a person smokes or chews tobacco, eats certain foods or vitamins, or has colored bacteria growing on the tongue.
Black discoloration on the top of the tongue may occur if a person takes bismuth preparations for an upset stomach. Brushing the tongue with a toothbrush or scraping it with a tongue scraper can remove such discoloration.
A small blue-black discoloration on the underside of the tongue may be a tattoo caused by a fragment of dental amalgam filling material, which contains silver.
A strawberry-red tongue may be the first sign of scarlet fever or, in a young child, a sign of Kawasaki disease.
A smooth red tongue and painful mouth may indicate general inflammation of the tongue (glossitis) or be caused by pellagra, a type of undernutrition caused by a deficiency of niacin (vitamin B3) in the diet.
In geographic tongue, some areas of the tongue are red and smooth (like ulcers), often surrounded by a white border. Other areas, appearing white or yellow and rough, may resemble psoriasis or be caused by psoriasis. The areas of discoloration often move around over a period of weeks to years. The condition is usually painless, and no treatment is needed. If people have symptoms, applying low doses of corticosteroids sometimes helps.
In fissured tongue, deep grooves are located on the tongue surface. The cause is unknown, but fissured tongue may occur with geographic tongue and some other disorders. Usually, there are no symptoms and no treatment is needed.
In "hairy" tongue, keratin (a normal body protein that is in hair, skin, and nails) accumulates on the normal projections on the top of the tongue (papillae) and gives it a hairy appearance. Hairy tongue may develop when food debris is trapped in the papillae when people do not clean their mouth adequately. The tongue may also appear hairy after a fever, after antibiotic treatment, or when peroxide mouthwash is used too often.
These "hairs" on the top of the tongue should not be confused with hairy leukoplakia. Hairy leukoplakia is white, hairy-appearing patches on the side of the tongue that is caused by the Epstein-Barr virus. It usually occurs in people with conditions that suppress the immune system, especially HIV infection.
Whitish patches on the tongue, similar to those sometimes found inside the cheeks, may be due to