Hairy Tongue: Definition, Causes, Signs, Symptoms, Diagnosis, Treatment and Prevention

It is a rare and benign condition known as a black hairy tongue or lingua nigra.

It is caused by excessive growth of bacteria, which accumulate in the papillae.

It is characterized by abnormal elongation that may look like hairs and a blackish or dark brownish discoloration or “staining” of these filiform elevations ( filiform papillae ) that cover most of the surface of the tongue (dorsum linguae).

Such changes often begin in the posterior region of the upper part of the tongue and extend towards the front (anterior) part of the surface of the language but never affect the lower surface.

Causes of hairy tongue

The specific underlying cause of hairy tongue is unknown. However, there are possible predisposing factors.

Hairy tongue is thought to result from failure of the typical “shedding” (peeling) of the outermost layer of the filiform papillae, overgrowth of certain bacteria or pigment-producing fungi commonly present in the mouth.

It can also be caused by an abnormal accumulation of pigment residue, keratin, or other debris in the oral area.


Keratin is a fibrous protein that is a primary component of the skin, nails, and hair.

Although the specific underlying cause of hairy tongue remains unknown, several potential predisposing factors have been implicated.

These factors include treatment with certain antibiotics, such as Tetracycline Therapy, which can cause the overgrowth of certain fungi.

Mouthwashes that contain astringents (such as menthol or witch hazel) or full-strength oxidizing agents, such as peroxide, can increase your risk of developing a black hairy tongue if you use them excessively.

The use of oral bismuth-containing drugs, in particular, smoking, chewing tobacco, excessive alcohol consumption, and poor oral hygiene.

Hairy tongue is not infectious, nor does it lead to oral cancer.

Affected populations

In men or women with hairy tongues, the age of onset is variable.

The hairy tongue most often affects adults; however, it can sometimes occur during childhood or adolescence.

Signs and symptoms

A hairy tongue is characterized by the elongation and overgrowth (hyperplasia) of the filiform papillae in “hair-like” projections and the development of a dark brown or black coating on the tongue’s surface.

Such changes typically occur in a triangular region in front of the circumvallate papillae, the giant papillae on the tongue.

These nodular elevations, typically eight to twelve in number, are arranged in a “V” shape.

Many people with hairy tongues have no associated (asymptomatic) symptoms.

However, some with the condition may be affected by nausea, taste disturbances, bad breath (halitosis), or other associated symptoms.

Hairy tongue diagnosis

The diagnosis is based on the physical examination and the medical history, where the appearance and possible factors that influence its appearance are evaluated.

Some other disorders and conditions can cause abnormal color changes or other changes in the tongue.

Such conditions and disorders are typically characterized by symptoms and physical findings that differ from those associated with the hairy tongue.

In people with suspected hairy tongues, doctors, dentists, or oral surgeons must perform a thorough evaluation to exclude other underlying conditions and to confirm the diagnosis of hairy tongue.


In some cases, the hairy tongue can disappear spontaneously. It usually disappears with proper oral hygiene.

Recommended treatment measures usually include:

  • Eliminating possible predisposing factors, such as quitting smoking.
  • Discontinuing antibiotic therapy if possible.
  • Receiving appropriate alternative treatments as needed under the direction of a physician and other right medicines.

Additionally, affected individuals should speak with dental specialists for guidance on appropriate measures to improve oral hygiene in their particular case.

Such measures generally include regularly using a soft bristle brush to clean the tongue.

In some individuals with a hairy tongue, the administration of specific topical agents (keratolytic agents), such as urea or tretinoin (a derivative of vitamin A), may be recommended to decrease the threadlike overgrowth.

This removal is done by promoting proper “shedding” (desquamation) of the outermost part of the papillae.

More research is needed to determine such hairy tongue therapies’ long-term safety and efficacy.

Hairy tongue prevention

Brushing should be done twice a day, and gentle brushing of the tongue should be performed as part of the routine.

When using mouthwash, use a solution diluted with one to five parts of water, and then rinse with running water.