Why Is My Tongue Black? (2024)

Opening your mouth and seeing a black tongue may be unsettling, but, in most cases, it is the result of a relatively harmless condition called black hairy tongue syndrome (BHT).

Also known as lingua villosa nigra, BHT is so-named because it causes a furry black patch near the back of the tongue that can't be readily scraped off. It is largely associated with lifestyle factors like smoking, poor oral hygiene, a soft diet, and the use of certain medications. BHT usually clears on with improved dental care and lifestyle changes.

A black tongue may also be due to tongue staining. In rare cases, it may be a sign of an underlying medical condition, such as diabetes or HIV.

What Is Black Hairy Tongue?

Black hairy tongue syndrome (BHT) is a benign condition in which the small bumps on the surface of the tongue, called papillae, become elongated and take on a black or brownish color. The elongated papillae give BHT it characteristically hairy appearance.

BHT typically affects the upper backside of the throat, called the dorsal throat, although it has been known to cause patches on the sides and middle of the tongue. These patches may sometimes appear yellowish or green.

BHT is usually asymptomatic (without symptoms), although some people may experience additional signs and symptoms like:

• Bad breath (halitosis)
• Burning mouth and tongue sensations (glossodynia)
• A metallic or off-putting taste (dysgeusia)
  

Besides its furry appearance, another factor that differentiates BHT from other causes is that it can be reduced by brushing or scraping but not entirely eliminated. BHT will typically recur until the underlying causes are identified and addressed.

What Causes Black Hairy Tongue Syndrome?

The cause of BHT is not entirely clear, but it is thought to be multifactorial (meaning involving a combination of lifestyle and/or health factors).

From a biological standpoint, BHT occurs when normal cells at the black of the tongue, called epithelial cells, start to accumulate and provide a haven to otherwise harmless chromogenic (color-producing) bacteria. These are the same bacteria that cause teeth staining if you do not brush.

Trapped in these havens, the bacteria start to secrete pigments that cause discoloration. At the same time, the bacterial buildup slows the normal shedding of cells from papillae, causing them to elongate and take on a hairy appearance.

Risk Factors

There are many risk factors associated with BHT. These include lifestyle, medications, and medical conditions that predispose individuals to this otherwise benign (non-cancerous) condition.

Lifestyle factors associated with BHT include:

• Heavy smoking
• Heavy coffee or black tea consumption
• Heavy alcohol consumption
• Poor oral hygiene
• A soft diet
• Prolonged use of mouthwashes containing sodium perborate, sodium peroxide, and hydrogen peroxide
• Chronic dehydration
• Intravenous drug use

Certain medications can also cause BHT, either independently or in tandem with lifestyle risk factors. These mainly involve antibiotics and certain antipsychotic drugs like:

• Penicillin
• Aureomycin
• Erythromycin
• Doxycycline
• Neomycin
• Olanzapine
• Chlorpromazine

Medical conditions associated with BH include those that cause immunosuppression (a weakened immune system) or directly or indirectly affect the tongue and mouth, including:

• Dry mouth syndrome
• Trigeminal neuralgia
• HIV
• Cancer
• Stem-cell transplantation
• Head and neck radiation
• General poor health and illness

For reasons that are not entirely clear, males are affected by BHT three times more often than females. While BHT can affect any age group, older adults are more commonly affected.

How Is Black Hairy Tongue Treated?

You can treat BHT by practicing good oral hygiene and modifying certain behaviors that contribute to the condition.

Examples include:

• Brushing and flossing daily
• Scraping or brushing the tongue as part of your oral hygiene practices
• Switching to non-peroxide mouthwashes like Crest Pro-Health Rinse’ and Zero-Alcohol Listerine which contain cetylpyridinium chloride
• Quitting cigarettes
• Cutting back on coffee
• Switching from black tea to herbal or green tea
• Limiting your alcohol intake
• Drinking plenty of water daily
• Using an over-the-counter (OTC) saliva substitute if you have dry mouth syndrome

Since antibiotics are rarely prescribed for long-term use, BHT will usually resolve once treatment is stopped. Even so, good oral hygiene can help speed the resolution of symptoms.

With antipsychotics like olanzapine and chlorpromazine (both of which cause dry mouth), stopping or changing treatment may not be an option. Treatment instead would involve improved oral hygiene and other therapeutic measures, like saliva substitutes and moisturizing sprays or gels.

Other Causes of Black Tongue

BHT may be the prime suspect if you have a black tongue, but there are other possible explanations—particularly if your tongue is not hairy or your hairy tongue is not black.

A medical term commonly used to describe a black tongue is melanoglossia. Although "melanoglossia" and "lingua villosa nigra" are sometimes used synonymously, melanoglossia describes a blackish discoloration with or without hairiness.

One example of this is a condition called pseudo-black hairy tongue in which the discoloration is due to staining rather than the overgrowth of chromogenic bacteria.

Possible causes include:

• Oral medications containing bismuth subsalicylate, like Pepto-Bismol
• Iron supplements
• Licorice

A black tongue may also be a sign of an underlying condition unrelated to either BHT or pseudo-BHT, such as:

• Acanthosis nigricans: This is a condition often seen in people with obesity or diabetes that causes patches of dark, thick velvety skin in body folds and creases. In 25% to 50% of cases, the tongue and lips are involved.
• Oral hairy leukoplakia (OHL): This is a condition often seen in people with untreated HIV that causes white patches on the side of the tongue with a hairy appearance. These patches can sometimes appear gray and cannot be removed with scraping.
• Pigmented fungiform papillae (PFP) of the tongue: This is a rare condition of unknown origin that can cause hyperpigmentation (darkening) of papillae on the tongues, creating a darkened "cobblestone" appearance rather than well-defined patches.
• Congenital lingual melanotic macule: This is a condition a person is born with that causes the overproduction of a pigment called melanin. This can cause very dark, non-hairy patches on the tongue that are generally benign. Dark-skinned people are more often affected.

Each of these conditions has features that help differentiate it from BHT. To confirm the diagnosis, a biopsy may be ordered. This involves removing a small tissue sample from the tongue to evaluate in the lab.

Summary

A black tongue is often the result of a benign condition called black hairy tongue syndrome (BHT). This may be caused by lifestyle factors like smoking, medications like antibiotics, and medical conditions like trigeminal neuralgia and dry mouth syndrome. BHT can usually be cleared with improved oral hygiene, smoking cessation, and a reduction in coffee, black tea, and alcohol.

A black tongue may also be caused by staining from things like Pepto-Bismol, iron supplements, and licorice. Less common causes of a black tongue include acanthosis nigricans, oral hairy leukoplakia, pigmented fungiform papillae of the tongue, and congential lingual melanotic macules.