There are three types of coated tongue--white tongue, yellow tongue and black, hairy tongue. All occur for different reasons. According to the Mayo Clinic, all are usually temporary, harmless conditions.
A white coating occurs when the tiny bumps on the tongue, known as papillae, become inflamed. Inflammation usually happens because of dehydration, fever, mouth breathing or smoking. Food debris, bacteria and dead cells then get lodged between the swollen papillae and create the white coating.
A yellow coating on the tongue is also caused by inflammation of the papillae, which then collect yellow bacteria. Smoking, mouth breathing, dehydration and fever all cause the papillae to become inflamed.
Black, Hairy Tongue
Black, hairy tongue is characterised by black or brown discolouration of the tongue, along with a hairy or furry coating. Black, hairy tongue is harmless. According to the National Institutes of Health, it sometimes occurs in people with AIDS.
The causes of black, hairy tongue include poor oral hygiene and excessive use of medications containing bismuth, such as Pepto-Bismol. Other causes include antibiotic use, which can change the normal bacteria content in the mouth. Heavy tobacco use is also a cause.
Treatment of White Tongue
Brushing the tongue can help get rid of white tongue. Drinking plenty of water and eating crunchy foods--such as apples, broccoli or popcorn--can also help remove the white debris from the tongue. Smokers should quit smoking.
Treatment of Yellow Tongue
For yellow tongue, the Mayo Clinic recommends a home treatment involving gentle brushing of the tongue with a solution of one part hydrogen peroxide and five parts water. Yellow tongue can indicate a problem with your liver or gallbladder, although it is rare.
Treatment of Black Tongue
Brushing your teeth and tongue twice a day is the recommended treatment for black, hairy tongue. If coated tongue of any type persists for more than seven to 10 days, you should consult a doctor or dentist.