Lingua Nigra: A Black Tongue and Its Causes

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Lingua Nigra: A Comprehensive Guide


Lingua nigra is a rare and benign condition characterized by a black discoloration of the tongue. It is typically caused by an overgrowth of certain types of bacteria and, in most cases, does not pose any serious health risks. However, it can be unsightly and may cause concern due to its unusual appearance.


The exact cause of lingua nigra is not fully understood, but it is believed to be linked to the overgrowth of chromogenic bacteria, namely Actinomyces species and Bacteroides melaninogenicus. These bacteria produce pigments that accumulate on the surface of the tongue, resulting in its black coloration.

Lingua nigra is often associated with the following factors:

  • Poor Oral Hygiene: Inadequate brushing and flossing can create an environment conducive to bacterial overgrowth.
  • Dry Mouth: Xerostomia, or dry mouth, can reduce saliva flow and the natural cleansing action it provides.
  • Certain Medications: Long-term use of antibiotics, bismuth, or certain mouthwashes can disrupt the oral microbiome and promote bacterial overgrowth.
  • Underlying Medical Conditions: Certain underlying medical conditions, such as diabetes, pernicious anemia, or HIV, can compromise the immune system and increase the risk of developing lingua nigra.
  • Smoking: Smoking can create a dry mouth environment and contribute to the overgrowth of chromogenic bacteria.


The primary symptom of lingua nigra is the black discoloration of the tongue. The discoloration typically covers the middle or posterior portion of the tongue and has a hairy or furry appearance. In some cases, the tongue may also be coated with a thick, white or yellow layer underneath the black discoloration.

Other symptoms may include:

  • Bad breath (halitosis)
  • Altered taste sensation
  • Nausea or vomiting (rare)


Lingua nigra is typically diagnosed based on its characteristic appearance. A physical examination of the tongue by a healthcare professional is usually sufficient to make a diagnosis. However, in some cases, a biopsy may be performed to rule out other conditions, such as oral cancer.


In most cases, lingua nigra does not require treatment as it is a harmless condition that resolves on its own. However, if the discoloration is causing discomfort or concern, several treatment options are available:

  • Improved Oral Hygiene: Meticulous brushing and flossing twice daily can help remove bacteria and debris from the tongue.
  • Over-the-Counter Remedies: Antibacterial mouthwashes or gels containing chlorhexidine or cetylpyridinium chloride can suppress bacterial growth.
  • Prescription Medications: In severe cases, antibiotics may be prescribed to kill bacteria and resolve the discoloration.
  • Tongue Scraping: Gently scraping the tongue with a tongue scraper can remove the discolored layer of bacteria.


Preventing lingua nigra can be challenging, but practicing good oral hygiene habits can reduce the risk:

  • Brush and floss teeth twice daily, including the tongue.
  • Use an antibacterial mouthwash to kill bacteria and prevent overgrowth.
  • Quit smoking to reduce dryness and harmful bacteria.
  • Visit the dentist regularly for professional cleanings and examinations.
  • Maintain good hydration to prevent dry mouth.
  • Manage underlying medical conditions that may increase the risk of lingua nigra.

Associated Conditions

Lingua nigra is often associated with certain medical conditions, including:

  • Oral Thrush: A fungal infection caused by Candida albicans that can lead to a black or brown discoloration of the tongue.
  • Hairy Tongue: Also known as lingua villosa, this condition is characterized by an overgrowth of papillae on the tongue, giving it a hairy or furred appearance.
  • Oral Cancer: A rare form of cancer that can manifest as a black patch or ulcer on the tongue.


Lingua nigra is generally a benign condition and does not cause any serious health complications. However, in rare cases, it may be associated with:

  • Oral Malodor: The overgrowth of bacteria can lead to bad breath.
  • Taste Disturbances: The black discoloration and bacterial overgrowth can alter the taste sensation.
  • Psychological Distress: The unsightly appearance of lingua nigra can cause anxiety or embarrassment.


Lingua nigra typically resolves within a few weeks to months with proper oral hygiene and treatment. In most cases, the discoloration disappears without leaving any permanent damage to the tongue. However, it is important to address any underlying medical conditions that may have contributed to the development of lingua nigra to prevent recurrence.


Lingua nigra is a rare and benign condition that causes a black discoloration of the tongue. It is often associated with poor oral hygiene, dry mouth, and certain medications. While it is typically harmless, it can be unsightly and may cause concern. Good oral hygiene practices, such as regular brushing and flossing, can prevent and resolve lingua nigra in most cases. If the discoloration persists or causes discomfort, seeking professional dental advice is recommended to rule out any underlying medical conditions and receive appropriate treatment.

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