The goal of the YouScript personalized prescribing system is to improve patient outcomes by preventing ADEs caused by drug-drug, drug-gene and drug-drug-gene interactions. ADEs are defined to include prescription and over-the-counter (OTC) drug overdose toxicity, adverse drug reactions (ADRs), and treatment failures generally caused by properly prescribed medications. The YouScript system prevents ADEs by the combined analysis of patient drug regimens and individual genetics. YouScript DNA drug sensitivity testing includes five enzymes in the cytochrome P450 (CYP) group (CYP2D6, CYP2C9, CYP2C19, CYP3A4, and CYP3A5). YouScript synthesizes decades of publicly funded basic and clinical research to provide actionable information to physicians treating patients.