What causes tongue discoloration?

Causes of Tongue Discoloration

Tongue discoloration can be caused by various conditions including infections, systemic diseases, medications, and lifestyle factors, with the most common being candidiasis, black hairy tongue, and geographic tongue. 1, 2

Inflammatory Conditions

• Burning mouth syndrome (BMS) presents with a bright red tongue and burning sensation, predominantly affecting peri- and post-menopausal women, often accompanied by dry mouth and abnormal taste 1
• Geographic tongue causes irregular red patches with white borders that migrate across the tongue surface, is benign and typically doesn't require treatment 2
• Fissured tongue presents with grooves or fissures on the dorsal surface of the tongue and is usually a benign condition 2

Infectious Causes

• Candidiasis (oral thrush) can cause a bright red tongue after white plaques are removed, commonly seen in immunocompromised patients and diagnosed by microscopic examination with KOH preparation 1, 3
• Scarlet fever (Group A Streptococcal infection) presents with "strawberry tongue" - initially white-coated then bright red with prominent papillae, accompanied by fever and characteristic rash 1
• Oral hairy leukoplakia, caused by Epstein-Barr virus, can be a marker for immunodeficiency and is treated with oral antivirals 2

Systemic Conditions

• Kawasaki disease presents with a red, swollen "strawberry tongue," primarily affecting children, associated with fever, lymphadenopathy, rash, and swollen extremities 1, 3
• Atrophic glossitis (smooth, red tongue) is often linked to nutritional deficiencies of iron, folic acid, vitamin B12, riboflavin, or niacin and resolves with correction of the underlying condition 2
• Vasculitis can present with a bright red tongue and often involves multiple organ systems 1
• Thyroid disorders, particularly hyperthyroidism, can cause tongue erythema 1

Medication-Induced Discoloration

• Black tongue can be caused by antibiotics including linezolid 4, amoxicillin/clavulanic acid 5, and tetracyclines such as doxycycline and minocycline 6, 7
• Various medications can cause tongue disorders, with the most common being glossitis, tongue edema, tongue discoloration, and burning tongue 7
• Drug-induced tongue disorders are predominantly observed with medications affecting the nervous system, anti-infectives for systemic use, and drugs for the alimentary tract and metabolism 7

Black Hairy Tongue

• Black hairy tongue (lingua villosa nigra) is characterized by elongated filiform papillae on the dorsum of the tongue giving a hairy appearance 8
• The condition can affect all ages, including infants, though it's more common in adults over 30-40 years 8
• The overgrown papillae can accumulate fungi, bacteria, food pigments, or other debris contributing to the discoloration 8
• Predisposing factors include poor oral hygiene, smoking, excessive coffee/tea consumption, and certain medications 8, 4
• Treatment involves gentle tongue brushing or scraping and elimination of predisposing factors 8

Other Causes of Tongue Discoloration

• Tongue piercings can cause local inflammation and discoloration during the healing period (3-6 weeks) 3
• Dental implant treatment in patients with renal failure on dialysis may lead to tongue discoloration due to uremic stomatitis 3
• Brown discoloration of the tongue can occur in patients with chronic kidney disease due to elevated salivary urea and phosphorus levels 3

Diagnostic Approach

• Clinical examination of tongue morphology, including color, texture, and pattern of discoloration 2
• Thorough history including onset, duration, associated symptoms, and use of tobacco, alcohol, and medications 2, 7
• Assessment for lymphadenopathy and other systemic symptoms 2
• In cases of suspected infection, appropriate cultures or microscopic examination 3, 1
• Biopsy may be necessary to differentiate benign lesions from premalignant or malignant conditions 2

Management Principles

• Treatment should target the underlying cause when identified 1, 2
• For candidal infections, appropriate antifungal therapy is recommended 3, 1
• For bacterial infections such as scarlet fever, appropriate antibiotics should be prescribed 1
• For black hairy tongue, gentle tongue brushing and addressing predisposing factors is usually effective 8
• For medication-induced discoloration, consider alternative medications when possible 7, 4, 5
• For nutritional deficiencies, supplementation of the deficient nutrient is recommended 2

Remember that while many tongue discolorations are benign and self-limiting, persistent or concerning changes should be evaluated by a healthcare professional to rule out serious underlying conditions.