Dark tongue

Alternative names
Tongue problems

Tongue problems include soreness, enlargement, or irregularities of the tongue.


Tongue problems may include pain, hairy appearance, unusual color, unusual smoothness, swelling, mouth ulcers, white lining, a split or groove in the tongue (fissure), cobblestone appearance, or positioning off to one side.

The tongue is mainly composed of muscles. It is covered with a mucous membrane. Small bumps (papillae) cover the upper surface of the tongue. Between the papillae are the taste buds, which provide the sense of taste. In addition to taste, the tongue functions in moving food to aid chewing and swallowing, and it is important in speech. Changes in appearance of the tongue may indicate a primary tongue disorder or may be a symptom of other disorders.


This is most often caused by damage to the hypoglossal nerve (cranial nerve XII). It may also be caused by ankyloglossia (tongue-tie), a disorder where the band of tissue that attaches the tongue to the floor of the mouth (frenulum) is too short. These disorders rarely cause difficulty but may result in speech difficulties or difficulty moving food during chewing and swallowing.


This can be caused by damage to the taste buds, neurologic abnormalities, side effects of medications, infections, and many other conditions. The tongue normally senses sweet, salty, sour, and bitter tastes. Other “tastes” are actually a function of the sense of smell.


This occurs with Down’s syndrome, acromegaly, myxedema, amyloidosis, rhabdomyoma, and other disorders. The tongue may broaden in persons with no teeth who do not have dentures.


These occur with inflammation of the tongue (glossitis). Papillae are lost, causing the tongue to appear smooth. Geographic Tongue (benign migratory glossitis) is a patchy form of glossitis where the location of inflammation and appearance changes from day to day.


This is a harmless condition that involves enlargement and profusion of tongue papillae, causing the tongue to appear hairy or furry. Hairy tongue is not a harmful disorder, although its appearance can be worrisome. The disorder usually clears with antibiotics.


This occurs occasionally. The upper surface of the tongue turns black or brown in color, and in some cases the papillae elongate. This is an unsightly condition but not harmful.


This may occur with glossitis and geographic tongue. It may also occur in some post-menopausal women (for unknown reason) and with diabetic neuropathy. The tongue may be a site of oral cancer, mouth ulcers, and leukoplakia.

Common Causes

  • Minor infections or irritations are the most common cause of tongue soreness.  
  • A viral ulcer or “canker sore” commonly appears on the tongue (or anywhere in the mouth) for no apparent reason. While it is not medically proven some doctors believe that viral ulcers are linked to emotional stress, fatigue, or lowered resistance.  
  • Injury (biting the tongue) can cause painful sores.  
  • A hangover or an allergic reaction to food or medication can cause a swollen tongue.  
  • Heavy smoking will irritate the tongue and make it painful.  
  • A smooth and pale tongue surface suggests nutritional (vitamin B-12) deficiencies.  
  • A coated tongue may be caused by dehydration, oral sex, or antibiotic side effects (such as thrush).  
  • An allergic reaction to food or medication can cause tongue swelling.  
  • A “hairy” appearing tongue (hairy leukoplakia) is a complication of AIDS.

Possible causes of tongue pain:

  • anemia  
  • cancer  
  • dentures that irritate the tongue  
  • oral herpes (ulcers)  
  • neuralgia  
  • referred pain from teeth and gums  
  • referred pain from the heart

Possible causes of tongue tremor:

  • neurological disorder  
  • overactive thyroid

Possible causes of white tongue:

  • local irritation  
  • smoking and alcohol use

Possible causes of smooth tongue:

  • anemia  
  • vitamin B-12 deficiency

Possible causes of red (ranging from pink to magenta) tongue:

  • folic acid and vitamin B-12 deficiency  
  • pellagra  
  • pernicious anemia  
  • Plummer-Vinson syndrome  
  • sprue

Possible causes of tongue swelling:

  • acromegaly  
  • amyloidosis  
  • strep infection  
  • Beckwith’s syndrome  
  • cancer of the tongue  
  • congenital micrognathia  
  • Down’s syndrome  
  • hypothyroidism  
  • infection  
  • leukemia  
  • lymphangioma  
  • neurofibromatosis  
  • pellagra  
  • pernicious anemia  
  • tumor of the pituitary gland

Possible causes of a hairy tongue:

  • antibiotic therapy  
  • bacteria, food, tobacco, coffee, or dyes in drugs and food  
  • chronic debilitating disorders  
  • habitual use of mouthwashes containing oxidizing or astringent agents.  
  • irradiation of the head and neck

Possible cause of tongue fissure (grooves in the tongue):

  • congenital defect (normally occurs in 10% of population)

Home Care
Practice good oral hygiene for hairy tongue and black tongue. Be sure to eat a well-balanced diet.

Canker sores are caused by viruses and can’t be cured by treatment. They must heal on their own. Be patient.

For tongue problems caused by dentures, see your dentist about making adjustments.

For a swollen tongue caused by allergies, antihistamines can help. Avoid the offending food or drug.

Call your health care provider if

  • the tongue problem is persistent.

What to expect at your health care provider’s office
The doctor will perform a physical examination, look closely at the tongue, and ask question such as:

  • When was it first noticed? Have you had similar symptoms before?  
  • Is there pain or swelling?  
  • Is there difficulty swallowing?  
  • Is there a tremor?  
  • What makes the problem worse? (Eating, drinking, swallowing, talking)  
  • Do you have dentures?  
  • What have you tried that helps?  
  • Are there problems with the teeth, gums, lips, or throat?  
  • Is the tongue bleeding?  
  • Is there a rash? Is there a fever?  
  • Do you have allergies?  
  • Are there problems with breathing, speaking, or moving the tongue?  
  • Have you noticed changes in taste?  
  • What medications are being taken?  
  • Do you smoke cigarettes, cigars, or a pipe?  
  • Do you use alcohol excessively?

Diagnostic tests will be determined by other symptoms. Blood tests may be used to confirm specific disorders, particularly systemic causes of tongue disorders. Biopsy of tongue lesions may be required in some cases.


Treatment depends on the cause of the tongue problem.

  • Cranial Nerve (CN) XII paralysis is usually treated by treating the cause of the disorder if possible. Therapy may be needed to improve speech and swallowing ability.  
  • Ankyloglossia (tongue-tie) may not require treatment unless speech or swallowing difficulties occur. Surgical cutting of the frenulum will release the tongue and relieve the problem.  
  • Mouth ulcers, leukoplakia, oral cancer, and other lesions can be treated by surgical removal of the lesion and/or various medications (see the specific disorder).  
  • Glossitis and geographic tongue are treated by treating the cause of irritation or inflammation.  
  • Medications prescribed may include corticosteroids to reduce inflammation, and antibiotics or antifungal medications.  
  • Other treatments may include treatment for anemia and other disorders, and removal of the source of irritation.


Johns Hopkins patient information

Last revised: December 4, 2012
by Harutyun Medina, M.D.

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