What Causes Blackheads on the Tongue
The term "blackheads" on the tongue is a misnomer—what you're likely observing is black hairy tongue (BHT), a benign condition caused by accumulation of keratin on elongated filiform papillae, not comedones like facial blackheads.
Primary Mechanism
Black hairy tongue results from defective desquamation and keratin accumulation on the filiform papillae of the tongue's dorsum, creating a carpet-like appearance that traps chromogenic bacteria and fungi, producing the characteristic dark discoloration 1.
The "hairs" are actually elongated filiform papillae with accumulated keratinized layers, between which fungi and bacteria colonize, contributing to the black or brown pigmentation 2.
Common Predisposing Factors
Lifestyle and Hygiene
- Smoking is the most common predisposing factor, along with excessive coffee or black tea consumption 1.
- Poor oral hygiene allows bacterial and fungal overgrowth that contributes to pigmentation 1.
- Xerostomia (dry mouth) impairs normal tongue desquamation 1.
Medications
- Antibiotics, particularly linezolid, can trigger BHT by altering oral flora 3.
- Other implicated medications include steroids, methyldopa, and olanzapine 3.
- Peroxide-containing mouthwashes may predispose to the condition 3.
Medical Conditions
- General debilitation and immunosuppression increase risk 1.
- Post-transplant patients may develop BHT as a cutaneous manifestation of graft-versus-host disease (GVHD), often preceding other GVHD symptoms 4.
- Trigeminal neuralgia has been associated with BHT 1.
Critical Diagnostic Considerations
BHT is typically asymptomatic aside from aesthetic concerns, though some patients experience burning mouth syndrome, halitosis, nausea, gagging, or dysgeusia 1.
Visual diagnosis is usually sufficient, showing brown-to-black discoloration of the tongue dorsum with elongated papillae 5, 1.
Histopathologic evaluation is recommended in post-transplant patients or when other concerning features are present, as BHT can be an early sign of GVHD with important prognostic implications 4.
Important Differential Diagnoses to Exclude
While BHT is benign, you must exclude:
- Pseudo-BHT, acanthosis nigricans, oral hairy leukoplakia 1
- Pigmented fungiform papillae 1
- Congenital melanocytic nevi or macules 1
- In rare cases, tongue malignancy can coexist with BHT 2
Management Approach
Identify and discontinue the offending agent (medications, smoking, excessive coffee/tea) 1.
Implement gentle mechanical debridement with a soft toothbrush or tongue scraper to promote desquamation 1.
Maintain adequate oral hygiene as the cornerstone of treatment 1.
Reassure the patient of the benign nature of the condition, as aesthetic concerns are the primary complaint 1.
Prognosis is excellent with treatment of underlying conditions and modification of predisposing factors 1.
Common Pitfall
Do not confuse BHT with actual comedones (blackheads)—these are entirely different entities. BHT involves keratin accumulation on tongue papillae, while facial blackheads are dilated hair follicles filled with sebum and keratin. The tongue lacks sebaceous glands and cannot develop true blackheads.