There is increasing attention focused upon cannabidiol (CBD), a non‐psychoactive derivative from cannabis that is advocated for various therapeutic uses. CBD undergoes metabolism via the CYP3A4 and CYP2C19 isoenzymes, and it appears that the compound may also be a potent inhibitor of these metabolic pathways. A recent case report describes an apparent drug‐drug interaction between CBD and tacrolimus. After treatment with CBD for epilepsy, an approximately 3‐fold increase in dose normalized tacrolimus concentrations was observed after treatment with the cannabinoid. The authors postulate a drug interaction and flag a potential concern in the context of increasing cannabinoid usage for medical purposes.