Conclusions
The current case presents an unexpected interaction between voriconazole and atazanavir/ritonavir due to impaired CYP2C19 activity and concomitant CYP3A4 inhibitors, which reminded us to consider the effect of gene polymorphisms on the drug interaction and the time of CYP450 recovery after inhibition, which was easily overlooked because the suspected drug was already stopped. Otherwise, regular dose adjustment would have resulted in severe adverse events or unsatisfactory therapeutic effects.