<!-- another tongue condition with "hairy" in the name, but completely different etiology -->
Black hairy tongue syndrome (BHT) is a condition of the tongue in which the small bumps on the tongue elongate with black or brown discoloration, giving a black and hairy appearance. The appearance may be alarming, but it is a harmless condition. Predisposing factors include smoking, xerostomia (dry mouth), soft diet, poor oral hygiene and certain medications. Management is facilitated by improving oral hygiene, especially scraping or brushing the tongue.
Signs and symptoms
thumb|A patient with black hairy tongue.
Hairy tongue largely occurs in the central part of the dorsal tongue, just anterior (in front) of the circumvallate papillae, although sometimes the entire dorsal surface may be involved.
Causes
The cause is uncertain,
Transient surface discoloration of the tongue and other soft tissues in the mouth can occur in the absence of hairy tongue. Causes include smoking (or betel chewing),<!-- pmid20027942 is listed as a review on pubmed, but I am not sure if it is actually a primary source... -->
Diagnosis
Diagnosis is usually made on the clinical appearance without the need for a tissue biopsy. Black tongue (lingua nigra) refers to a black discoloration of the tongue, which may or may not be associated with hairy tongue. However, the elongated papillae of hairy tongue usually develop discoloration due to growth of pigment producing bacteria and staining from food. Drug-induced black hairy tongue specifically refers to BHT that develops because of medication.
Black hairy tongue can also be caused by antibiotics e.g., (penicillins, cephalosporins, tetracyclines, clarithromycin and linezolid).
Treatment
Treatment is by reassurance, as the condition is benign, and then by correction of any predisposing factors. but people who are affected may be distressed at the appearance and possible halitosis, and therefore treatment is indicated.
Epidemiology
Hairy tongue occurs in about 0.5% of adults.