science concerned with the benefit and risk of drugs used in populations and the analysis of the outcomes of drug therapies

Pharmacoepidemiology studies the use and effects of drugs on large groups of people. It assesses good and bad effects, and risks for humans while using a particular drug.

Pharmacoepidemiology bridges pharmacology and epidemiology and borrows methodology from both of them. It uses descriptive epidemiological method by describing exposure to a drug and by calculating rates, e.g., incidence and prevalence. This produces a hypothesis about the drug, but does not test it. Pharmacoepidemiology also uses analytic epidemiological method by means of observation (case-control and cohort studies) and clinical trials. The analytic study compares an exposed group with a control group and tests the hypothesis.

Pharmacoepidemiology provides pharmacovigilance. That is continual monitoring of unwanted effects and other safety-related aspects of drugs. Pharmacovigilance is conducted by reporting systems through health care professionals who report adverse drug reactions to the central agency. The central agency combines reports from many sources to produce a more informative profile for drug products.