Recognizing drug-drug interactions (DDIs) has become increasingly important as the country's demographics have aged, resulting in more complex medication regimens. Budnitz and colleagues highlighted the frequency of adverse drug reactions (ADRs) and the substantial morbidity that results. Their study estimated >700,000 cases of ADRs in emergency rooms (ER) in the United States between 2004 and 2005, and that ADRs accounted for 6.7% of ER visits for unintentional injuries that led to hospitalization. Moreover, medications that require monitoring accounted for 41.5% of all the ADR-related hospitalizations.These data have tremendous implications for the field of psychiatry because many psychiatric drugs require therapeutic monitoring. The importance of DDIs is particularly relevant for the psychiatric population, where adverse effects not only cause short-term morbidity, but may lead to long-term treatment noncompliance. For many patients taking antipsychotics, adherence is the key to a successful outcome. Minimizing DDIs maximizes the chance that people will avoid unnecessary ADRs while achieving therapeutic drug levels.