Psychotropic agent-induced black hairy tongue.

Black hairy tongue is characterized by an abnormal coating of the dorsal surface of the tongue. Although the cause is unknown, several precipitating factors may be implicated in the pathogenesis of this disorder. A case is presented in which black hairy tongue appeared subsequent to the administration of fluoxetine hydrochloride, thiothixene hydrochloride, benztropine mesylate, and clonazepam for bipolar affective disorder.