White coated tongue is a relatively common symptom and usually it means nothing serious. However, it may be a sign of some serious condition those we should mention in this article. Generally speaking, some tongue coating exists by every person as it is a natural process of accumulation of dead mucosa cells.
Inadequate oral hygiene
Insufficient oral hygiene including unsatisfactory teeth brushing causes bad breath associated with white and coated tongue.
Insufficient fluid intake causes dryness of mucous membranes, including mucosa in mouth and tongue. This deteriorates its cleaning ability and leads to occurrence of a white cover.
Cigarette smoke contains many harmful substances. It directly damages the surface of tongue and causes drying of oral mucosa.
In this case the tongue (and possible other areas of oral mucosa) is covered by white coats of fungi origin. The most common fungus causing this condition is Candida albicans. The coatings can be wiped away, the mucosa beneath is often reddish and irritated. These infections are usually well treatable with antifungal agents, but their frequent recurrence can be a warning of certain immunodeficiency (typically diabetes-related).
Leukoplakia means white coloration of mucosa (not only on tongue) that may indicate a presence of precancerous lesion. When healthy mucosa faces any harmful effects for longer time, it may undergo some histological changes that are visible as white coloration. White patches of such mucosa can not be wiped away as they are not a coat but an integral part of the tongue. Leukoplakia can be a consequence of cigarette smoking and hard liquor drinking. Some forms or leukoplakia are associated with viral infections, leukoplakia on tongue’s edges (so-called hairy leukoplakia) may be a symptom of HIV infection.
In addition to medical history (oral hygiene, smoking, drinking alcoholic beverages, known immune disorders) and basic physical examination physicians can take smears for microbiological examination to diagnose fungal infections. When there is a suspicion of leukoplakia a small sample of tissue from target location can be obtained for histological examination to rule out precancerous changes.