Black hairy tongue is a relatively rare acquired condition that is considered harmless and
self-limited.
It is positively correlated with increasing age though there are cases reported even in
children.
Although "black" hairy tongue is typically described as a thickened area of black discoloration
on the surface of the tongue with the sides and tip being unaffected, the black color
descriptor is not universal.
The color can also be white, brown, and even blue.
Generally, having a black hairy tongue causes no other symptoms and treatment is pursued
due to aesthetic reasons.
So what exactly is going on when a black hairy tongue develops?
Anatomically, the tongue mucosa is normally covered by tiny taste buds called papillae.
Normally, the papillae are small protrusions of the tongue mucosa, typically rising less
than 1mm from the surface.
Along with taste, they function to increase friction between the tongue and food in order
to move particles around within the oral cavity.
However, in black hairy tongue, these normally <1mm tongue protrusions can grow to over 1cm
in length and 2mm width.
When these elongated protrusions are examined under the microscope, the “hairs” are
actually highly elongated cornified spines that result from delayed desquamation of the
cells in the central column of the papillae and marked retention of secondary papillary
cells that express hair-type keratins.
To use an analogy, think of a skinny tower of lego blocks.
Normally, after making a lego tower about 5 pieces high, each subsequent piece will
fall off due to instability.
With black hair tongue, this skinny lego tower is growing to 10 or 15 pieces high with subsequent
pieces being added not easily falling off like it normally should.
This carpet of abnormally long papillae protrusions then over time secondarily collect fungi,
bacteria, minerals and other inorganic particles which leads to the discoloration.
To reiterate, micro-organisms found in black hairy tongue is coincidental and not causative.
I will further stress that although fungi and bacteria may be present and do contribute
to the discoloration, there is no "infection" present per se.
These organisms are happily just living on the surface without actually invading the
tongue lining.
Treatment is really to address the long papillae and not so much what's on it.
This condition may mysteriously appear and just as mysteriously disappear for no perceivable
reason.
However, sometimes this condition can occur due to a precipitating trigger which when
corrected/avoided will often resolve the discoloration within weeks to months.
So, what are some of these triggers that might cause a black hairy tongue?
• Smoking • E-cigarettes
• Drinking alcohol • Poor oral hygiene
• Immunocompromise • Excessive coffee or black tea drinking
• Mouthwash (ie, listerine, scope, etc) • Pepto-Bismol
• Dry mouth • Prolonged soft diet
• Radiation cancer therapy to head/neck region
• Trigeminal Neuralgia
Medications generally encompassing antibiotics and psychotropics have also been reported
to cause black hairy tongue.
Treatment is geared towards FIRST avoiding any precipitating triggers and/or medications
as well as starting manual debridement.
Do practice great oral and dental hygiene, BUT avoid chemical mouthwashes of any kind
like listerine or scope as well as use a bland, SLS-free toothpaste (ie, CloSYS, TOMS).
When debriding the tongue, use a tongue scraper in order to manually remove not just organisms
and debris, but also to "cut" the abnormally long papillae shorter down to a more normal
small size.
If there is a heavy growth of thrush present, a course of prescription antifungal troches
can help, but again, will not correct this problem which is due to an anatomic elongation
of the papillae.
Antibiotics should be avoided which may actually exacerbate this problem.
To reiterate, there is no "infection" present.
The organisms are coincidental and not causal.
Second-line treatments are anecdotal with no single treatment proven to reliably cure/reverse
black hairy tongue.
These include:
• 1% Gentian Violet application to the tongue using a q-tip daily for 3 days
• Baking soda rinses (1/2 - 1 tsp of baking soda in 1 cup of water)
• 3% hydrogen peroxide rinses (although there are some anecdotal reports that this
may trigger black hairy tongue) • 50% trichloroacetic acid application
• 40% urea solution application • Salicylic acid application
• Topical and oral retinoids • Vitamin B complex
• Thymol application
If resolution is not forthcoming in spite of these interventions, a biopsy can be obtained
to confirm nothing else is going on before proceeding to more invasive options including
manually cutting the filiform papillae shorter with scissors/scalpel, carbon dioxide laser,
or electrodessication.