A 6-year-old girl was prescribed Metronidazole (20 mg/kg/day) plus lansoprazole (2 mg/kg/day) for Helicobacter pylori infection. At the second week, the child had black discoloration on tongue (Fig. 1) following the cessation of drugs. The black discoloration resolved in a week.

Fig 1. Black discoloration of tongue in patient.

Superficial transient discoloration of the dorsum of the tongue may be caused by some foods, beverages and drugs (such as iron salts, bismuth, chlorhexidine, lansoprazole, amoxicillin, clarithromycin). When such discoloration noticeably affects the posterior dorsum of the tongue with longer filiform papillae and stained dark brown or black, the term ‘black hairy tongue’ is used. Black tongue (lingua nigra) refers to a black discoloration of the tongue, which may or may not be associated with hairy tongue