To investigate the clinical diagnostic characteristics of linezolid-induced black hairy tongue.

The clinical data of a patient with black hairy tongue after linezolid treatment in the Department of Neurology, the First Bethune Hospital of Jilin University on September 26, 2020 were retrospectively analyzed. Additionally, relevant literature was reviewed to analyze the possible mechanism, clinical diagnostic characteristics, and prevention and treatment strategies of linezolid-induced black hairy tongue.

A 37-year-old female patient was admitted to the hospital for 1 week due to symptoms of headache, fever, nausea, and vomiting. Her diagnosis was bacterial meningitis (tuberculosis could not be ruled out). The patient was prescribed linezolid in combination with anti-tuberculosis medication. After 18 days of linezolid treatment, the dorsum of her tongue turned black, and visible hair-like alterations emerged after 23 days. Thirty days after stopping linezolid, the black tongue covering on the dorsum of the tongue vanished, so did the odd sensation in the oral cavity. Combined with the relevant literature, the median appearance time of black hairy tongue after taking linezolid was 14.0 (12.0, 21.0) days, while the average disappearance time of black hairy tongue after quitting linezolid was (13.4±6.6) days. Black hairy tongue was characterized by the extension and hypertrophy of the filiform papillae, as well as brown or black staining on the posterior dorsum of the tongue. On the assumption of excluding microbiological infection, the diagnosis of black hairy tongue relied on visual observation, and it would subside following drug withdrawal and the elimination of risk factors.

Black hairy tongue may be associated with the use of the linezolid. Clinically, the diagnosis can be made by the elongation and hypertrophy of the filiform papillae and the brown or black discoloration of the dorsum of the tongue.