Case of Moxifloxacin-Induced Black Hairy Tongue

BACKGROUND Black hairy tongue (BHT) is a relatively uncommon acquired benign condition, with a prevalence ranging from 0.6% to 11.3%. It presents as a superficial black hairy carpet-like lingual growth. The exact etiology of BHT remains unclear, and both extrinsic and intrinsic factors are potentially contributive. Several types of antibiotics are also associated with BHT, but no English reports of moxifloxacin-induced BHT exist. Here, we report the first case of moxifloxacin-induced BHT. CASE REPORT A 69-year-old woman presented with a brown and hairy tongue. She was taking prednisolone for mixed connective tissue disease and developed right finger flexor tenosynovitis, which was complicated by osteomyelitis due to Mycobacterium chelonae. Based on the susceptibility results, she was treated with tobramycin, imipenem, and clarithromycin for 6 weeks, and then switched to moxifloxacin and clarithromycin. Within 10 days, she developed brown discoloration on the dorsum of the tongue, with carpet-like elongated filiform lingual papillae. The diagnosis of BHT was made. After stopping moxifloxacin, improvement was seen within 2 days, and her right finger has shown no signs of recurrence for 12 months. CONCLUSIONS Clinicians should be vigilant against agents and lifestyles that can precipitate BHT, especially moxifloxacin. It is essential to counsel patients before such treatments to avoid patient anxiety or treatment changes.