Pharmacists have long known that using a patient's unique traits to drive pharmacological decision-making might increase medication responsiveness and reduce drug-related hazards. The first patient-specific parameters utilized to personalize medication were age, weight, and dietary habits. To assist drug selection and administration, precision pharmacotherapy includes the use of genomics, therapeutic drug monitoring, evaluation of liver and renal function, environmental and lifestyle exposures, and study of other unique patient or disease features. Precision pharmacotherapy assumes that before a medicine is delivered, either the doctor or the pharmacist evaluates the necessity of the addition to the patient's medication regimen as well as the risk caused by it.