Black hairy tongue is a rare condition, characterized by a black discoloration and hair-like structure appearing on the dorsal surface of the tongue. The mechanism of black hairy tongue remains unclear but could be predisposed by multiple factors. We described a case of a 53-year-old Chinese female with a diagnosis of bronchiectasis complicated with Mycobacterium abscessus infection, and a triple antibiotic regimen was prescribed for the infection. One month later, a black hairy tongue appeared. The clinical pharmacist was consulted to investigate the association of medication-related factors by the attending clinician, and the clinical pharmacist identified the potential cause and suggested an appropriate treatment for the black hairy tongue. The black hairy tongue disappeared and did not recur during subsequent treatment.