Black Tongue

The symptoms of a black tongue are:

• Black discolouration of the tongue 
• Yellow, tan-brown, greenish-white discolouration of the tongue
• Hairy, fur-like appearance on the top part of the tongue
• Bad breath (medically called halitosis)
• Metallic or bad taste in the mouth

The causes of black tongue are as follows:

• Poor oral hygiene: Those who do not maintain oral hygiene or clean their tongue tend to get a coating on top of their tongue which becomes more prominent with time.
• Medications: Medications like bismuth subsalicylate tablets used for the treatment of gastroesophageal reflux disease (GERD) leave a coating of sulfur (black in colour) on the tongue. Medications like meropenem and minocycline given for the treatment of microbial infections also result in a black hairy tongue.
• Xerostomia: When the mouth gets extremely dry, this condition is called xerostomia or dry mouth. Due to the lack of saliva in the mouth, food gets stuck on the surface of the tongue and gives it a tan-brown appearance. Some medical conditions that can cause dry mouth include diabetes and Sjogren's syndrome, an autoimmune disease in which the moisture-producing glands of the body are destroyed.
• Drinking excessive tea or coffee: Excess consumption of caffeine can lead to staining of the teeth and tongue. Tea and coffee stain the finger-like structures called papilla on the surface of the tongue. 
• Tobacco use: Tobacco chewing stains the elongated papillae of the tongue, giving them a black appearance.
• Smoking: Smoking stains the papillae of the tongue and also causes xerostomia, thus causing the build-up of black pigmentation on the tongue. (Read more: Effects of smoking on the teeth, gums and mouth)
• Continuous use of mouthwash: Regular use of mouthwash can lead to the staining of the papillae of the tongue as well the teeth as most mouthwashes contain oxidising agents like peroxide.
• HIV: Black hairy discolouration of the tongue can also be seen in people with HIV.

There are certain ways by which you can prevent black pigmentation of the tongue:

• Clean your teeth and tongue on a daily basis. Use a tongue scraper to clean the surface of the tongue. 
• If you have been diagnosed with xerostomia, your doctor may prescribe you some sugar-free gums (the ones containing xylitol), lozenges or artificial saliva which will keep your mouth moist.
• Cut down on the amount of tea and coffee you drink in a day to avoid staining of the tongue and teeth.
• Quit using tobacco, both smoked and smoke-less, avoid staining of the tongue and teeth.
• Discontinue the use of mouthwashes after three weeks to avoid staining of the tongue and teeth.

Your dental surgeon can diagnose the condition while doing a regular oral examination. They may ask you some questions about your oral habits like smoking or drinking tea or coffee.

If you have diabetes or if you are taking medicines for GERD, let your doctor know about these to help them make an informed diagnosis and recommend treatment options accordingly. 

Your doctor may try to scrape the black coating present on the top of your tongue and send it to a lab for further examination. 

If HIV/AIDS is suspected, the doctor may draw blood samples to test for the presence of the virus.

Read more: HIV test

There is no specific treatment for black tongue, as it does not cause any harm to the person. But it can be managed by the following measures:

• Maintain good oral hygiene by brushing twice daily followed by tongue cleaning.
• Rinse your mouth thoroughly after eating or drinking anything.
• Get a dental checkup done every six months in order to rule out any abnormal changes in the oral cavity.
• Where relevant, the doctor may start medications for HIV positive cases in order to manage the symptoms of black tongue.