Predisposing factors include smoking, xerostomia (dry mouth), soft diet, poor oral hygiene and certain medications.

[6] Other possible associated factors are poor oral hygiene,[6] general debilitation,[6] hyposalivation (i.e., decreased salivary flow rate),[8] radiotherapy,[6] overgrowth of fungal or bacterial organisms,[6] and a soft diet.

[6] A soft diet may be involved as normally food has an abrasive action on the tongue, which keeps the filiform papillae short.

Causes include smoking (or betel chewing),[8] some foods and beverages (e.g., coffee, tea or liquorice),[8] and certain medications (e.g., chlorhexidine,[8] iron salts,[8] or bismuth subsalicylate (Pepto-Bismol)).

[6] However, when biopsies have been taken, the histologic appearance is one of marked elongation and hyperparakeratosis of the filiform papillae and numerous bacteria growing on the epithelial surface.

However, the elongated papillae of hairy tongue usually develop discoloration due to growth of pigment producing bacteria and staining from food.

[6] Other reported successful measures include sodium bicarbonate mouthrinses, eating pineapple, sucking on a peach stone and chewing gum.