A "hairy" or coated tongue is a fairly common problem, not usually associated with a serious illness or disease. The tongue's top layer has a coating, sometimes called a biofilm, which is made of keratin and an accumulation of bacteria, mould, mucus and remnants of food. Keratin's fibrous structural proteins serve as protective dead cells, safeguarding new cells as they are formed. A major component of hair, skin, nails and teeth, keratin is the same material that forms on your hands when you develop calluses. Although a coated tongue is usually harmless, the wild array of microorganisms living on it can be potential pathogens, causing infection and halitosis (bad breath).
The incidence of furry, hairy, white, yellow, brown or black tongue is directly related to the amount of keratin accumulated on a person's tongue. When eating, keratin is usually knocked off and swallowed, and an equal amount is reproduced. When enough keratin is not removed by eating, it accumulates, upsetting the balance and resulting in a colourful or coated tongue. According to the American Academy of Oral & Maxillofacial Pathology (AAOMP), drinking hot beverages, smoking and other irritations can cause increased keratin production. A coated tongue can appear white, yellow, brown or black; the colour is the result of different bacteria creating pigments while growing. A white tongue, sometimes called oral thrush, can be caused by an overgrowth of yeast (candida) in the mouth, commonly associated with asthma, diabetes or medications. Inflammation of papillae (taste receptors) due to poor oral hygiene, dehydration or smoking can also create a white coating on the tongue. Yellow tongue is the result of a bacterial inflammation that releases a yellow chemical into the papillae. Black or brown tongue is caused by an overgrowth of bacteria, giving the tongue a dark, furry appearance. Hairy tongue is a more severe form of coated tongue because it creates elongated, hairlike keratin projections on taste buds.
Good oral hygiene is the best way to control coated tongue. Regular removal of accumulated keratin, organisms and bacteria significantly reduce the coating. A tongue scraper, spatula or cotton swabs can be used daily to keep your tongue fresh and pink. Physical removal of the discoloured, top layer of your tongue reduces pathogenic bacteria and the degree of halitosis. Eliminating habits that irritate your tongue (like eating tortilla chips or drinking hot beverages) also helps. Briefly brushing your tongue with a weak combination of baking soda, 3 per cent hydrogen peroxide and water can also eradicate the coating on your tongue; however, to prevent irritation, do not leave the solution on your tongue for more than 15 seconds. Tongue scraping dislodges dead, stinky, keratinised cells, making more room for the growth of new cells.
Although it's usually harmless, sometimes a coated tongue indicates the presence of a serious medical problem. If you have white patches, stripes or dots on your tongue, it's essential to consult with a doctor or dentist. White patches or lesions on the tongue, cheeks or gums may be a sign of leukoplakia, a precursor to oral cancer. Leukoplakia is common among regular smokers and tobacco users. Hairy leukoplakia-- painless, fuzzy, white patches on the sides of a tongue--may be an early warning sign of HIV infection. Leukoplakia can also occur after a bone marrow transplant or in a person with a compromised immune system. White stripes or dots on the tongue, lips, cheeks or gums can indicate lichen planus, an inflammatory disease that can cause itching and painful ulcers in the mouth. Yellow tongue can be an indication of tuberculosis, acid reflux, indigestion, malabsorption syndrome, and liver or gallbladder problems. Canadian doctors working in Bolivia reported a connection between coated tongue and typhoid fever. After practicing tongue scraping and good oral hygiene, seek medical care if a coated tongue lasts for more than two weeks or if it is accompanied by pain or swelling.