Hairy or coated tongue is basically an overgrowth of the filiform papillae on the tongues of some otherwise healthy individuals. Long and even normal papillae can become discolored by food and drink (e.g. red wine and, yes, Pepto Bismol) The best way to control coated tongue is to scape the tongue daily with a spoon or low profile tongue scraper (available at drugstores or over the Web), brush the tongue and use diluted 3% hydrogen peroxide as a debriding mouthwash. (Dilution: 2 parts water to one part 3% --that is, medicinal -- hydrogen peroxide, an oxygenating agent). The causes of hairy or coated tongue often -- not always -- are not specifically detectable, and the control outlined above is the only means at present for many individuals of managing the condition. It is effective, however. Such factors as heavy smoking and -- as Lasagne says
-- long-term use of antibiotics have been reported to cause temporary coated or hairy tongue, but the condition appears to be normal and permanent in some individuals. Poor oral hygiene and failure to brush the teeth are not the causes. More research is needed. Read critically about this topic. Much misinformation and misconception surround it.