Life-threatening drug interactions: what the physician needs to know.

Adverse drug-drug interactions are a significant cause of adverse events and outcomes. Their incidence is rising, with more patients taking more drugs, and newer, more precise but often more hazardous drugs becoming available. Despite considerable information, including computerised alerts about potential adverse drug-drug interactions, prescribers increasingly override alerts, possibly symptomatic of the immense problem of evaluating the risk of an interaction in a particular patient. Many reports emanate from small studies often of normal and young volunteers, entirely different from the real world where, more often, older patients with multiple health conditions are receiving many more than the two drugs identified in the drug interaction report. Focusing on those drug-drug interactions that are clinically relevant is necessary, and increasingly, tools and reliable sources of this information are easily accessible.