Black hairy tongue: a spooky sign associated with penicillin therapy
Authors: Dennis A Nowak and Benjamin E Nowak
Published online: 1 August 2022
A 21-year-old man noticed a blackish discoloration of the tongue at day 6 of oral penicillin intake following the extraction of retained molars

A 21‐year‐old man noticed a blackish discoloration of the tongue (Figure, A) at day 6 of oral penicillin intake following the extraction of retained molars. Penicillin was discontinued. Fungal and bacterial cultures of a tongue swab were unremarkable. The discolouration disappeared within 10days after discontinuation of penicillin and tongue brushing (Figure, B–E). Black hairy tongue is a rare side effect of penicillin medication.1,2 It is characterised by hypertrophy and elongation of filiform papillae causing a brownish or greyish‐black darkening.1,2,3 The syndrome is associated with several causative factors including poor oral hygiene, tobacco use and antibiotic agents.2,3 Differential diagnoses include acanthosis nigricans and food colouring. Black hairy tongue is generally reversible and causes no long term sequelae.1,2,3
Competing interests
No relevant disclosures.
References
- Wolfson SA. Black hairy tongue associated with penicillin therapy. J Am Med Assoc 1949; 140: 1206‐1208.
- Ren J, Zheng Y, Du H, et al. Antibiotic‐induced black hairy tongue: two case reports and a review of the literature. J Intern Med Res 2020; 48: 300060520961279.
- Hamad Y, Warren DK. Black hairy tongue. N Engl J Med 2018; 379: e16.