This patient has black hairy tongue, and the correct management is tongue brushing as part of aggressive oral hygiene. Black hairy tongue is a benign and self-limited disorder related to several predisposing factors such as alcohol and tobacco use, poor oral hygiene, and medications (including bismuth, tetracycline, and linezolid). The clinical appearance of black discoloration and a thickened tongue without other symptoms is characteristic. Treatment includes aggressive oral hygiene with tongue brushing and scraping and modification of any risk factors (smoking cessation, avoidance of alcohol or medications inducing the change).

Amoxicillin-clavulanate is an antibiotic that is often used to treat oral infections. Black hairy tongue is not an infection that requires antibiotic treatment. The clinical appearance and the absence of oral or systemic symptoms make an oral infection as a cause of his findings unlikely.

A biopsy of the lesion is not indicated as this is a benign and self-limited condition. If the lesion is recalcitrant to therapy or if there are concerning manifestations such as leukoplakia or erythroplakia, a biopsy may be considered. Management with aggressive oral hygiene before biopsy is recommended.

Oral fluconazole is used for candidiasis oral infections, whereas black hairy tongue is a keratin build-up related to risk factors and poor oral hygiene.