What is white tongue?

Answer 1

White tongue, or more often, white hairy tongue (lingua villosa alba) is a benign (harmless) hypertrophy (overgrowth) of the filiform papillae, which grow from the surface of the tongue and are the most numerous of the papillae (the others being involved with taste).

Not being involved with taste, they are thought to have a mechanical function. For example, in cats, they constitute the abrasive surface of the tongue and are thought to aid in cleaning the fur. There are numerous suggestions as to how they may serve humans.

The etiology of hypertrophy of filiform papillae in humans is unknown - with systemic disease, diet, environmental factors, medications, and heredity being among those postulated. While ordinarily whitish, the papilla can become stained by foods or tobacco and assume corresponding colors.

If particularly long, hairy tongue might be a source of halitosis (bad breath) as food particles/debris might become entangled within their mass. Generally, vigorous brushing or scraping of the tongue can minimize halitosis by not only removing debris but also by removing some of the overgrowth of the papilla.

Regardless, it is important to remember that white hairy tongue is harmless.

Answer 2

Plaque. You're supposed to brush your tongue every night to keep it away.