Abstract
A black hairy tongue is a benign, self-limiting condition characterized by the discolouration of the tongue due to defective desquamation. Clinical presentation varies, with most cases being asymptomatic although aesthetically unpleasant to the patient. Prevalence varies geographically, ranging from 0.6% to 11.3%. It can be triggered by various factors such as medications, smoking, alcohol, poor oral hygiene, or even underlying systemic conditions such as malignancy. Several antibiotics such as doxycycline, erythromycin, amoxicillin-clavulanate, metronidazole, and piperacillin-tazobactam, have been reported to cause black hairy tongues. Onset can range from a few weeks to as long as five weeks. Diagnosis relies on clinical assessment with a good history and visual examination. Definitive treatment remains unclear, but the condition typically improves by identifying and discontinuing the causative agent and maintaining adequate oral hygiene. Complications are rare, and the prognosis is excellent. This case report aims to raise awareness of the association between the black hairy tongue and co-amoxiclav, which may impose additional burdens on patients, healthcare providers, and the health system if failed to be recognized and treated appropriately.