What causes grey or black residue on the tongue?

Causes of Grey or Black Residue on the Tongue

Black hairy tongue (lingua villosa nigra) is the most common cause of grey or black residue on the tongue, typically resulting from poor oral hygiene, medication use (particularly antibiotics), smoking, or certain medical conditions that affect oral care. 1

Primary Causes

Medications

• Bismuth subsalicylate (Pepto-Bismol) - Causes temporary darkening of the tongue 2, 3
• Antibiotics - Particularly ceftriaxone 4
• Antipsychotics 1
• Proton pump inhibitors - Such as pantoprazole 4

Lifestyle Factors

• Poor oral hygiene - Inadequate tongue cleaning 1
• Tobacco use - Smoking or chewing tobacco 1
• Excessive alcohol consumption 1

Medical Conditions

• Immunocompromised states - HIV/AIDS, cancer treatments 5, 1
• Medical conditions limiting ability to practice good oral hygiene 1
• Xerostomia (dry mouth) 1

Pathophysiology

Black hairy tongue occurs due to:

• Elongation of filiform papillae on the dorsal surface of the tongue 6
• Reduced desquamation (normal shedding) of the tongue surface cells
• Accumulation of debris, bacteria, fungi, food particles, and pigments on the elongated papillae 6
• Staining from chromogenic (color-producing) bacteria or external substances 1

Differential Diagnosis

When evaluating black or grey tongue residue, consider:

• Oral candidiasis - White, creamy plaques that can be scraped off 5
• Oral hairy leukoplakia - White patches that cannot be scraped off, often seen in immunocompromised patients 5
• Pigmented oral lesions - Including melanoma (rare) 5
• Geographic tongue - Patchy areas of smooth, red tissue with white borders
• Strawberry tongue - Associated with Kawasaki disease, showing red, swollen tongue 5

Diagnostic Approach

1. Visual examination - Assess color, distribution, and whether the residue can be scraped off
2. Medical history review - Focus on medication use, particularly bismuth products, antibiotics, and antipsychotics 1
3. Oral hygiene assessment - Evaluate tongue cleaning habits 5
4. Tongue brushing habits - Frequency of tongue cleaning 5

Management

Self-Care Measures

• Gentle tongue brushing or scraping - Most effective first-line treatment 6
• Improved oral hygiene - Regular brushing with soft toothbrush 7
• Discontinuation of causative agents - If medication-related 3, 4

Professional Care

• Dental evaluation - For persistent cases 1
• Treatment of underlying conditions - If related to systemic disease 1
• Traditional Chinese Medicine - Has shown effectiveness in some cases 8

Prognosis

The prognosis for black hairy tongue is excellent 1, 6:

• Self-limiting condition in most cases
• Typically resolves within days to weeks after addressing the underlying cause
• No long-term complications when properly managed

Prevention

• Regular tongue cleaning - As part of daily oral hygiene routine 7
• Avoiding known triggers - Such as tobacco products 1
• Proper medication management - Be aware of medications that can cause tongue discoloration 1
• Regular dental check-ups - Especially for those at higher risk 1

Black hairy tongue, while alarming in appearance, is generally harmless and responds well to improved oral hygiene and elimination of contributing factors.