Pharmacoepidemiology is a term that refers to the study of the effects and use of drugs in large groups of individuals. It is the joining of pharmacology with epidemiology. It is the clinical study of the effects of drugs on humans.

One part of the work of clinical pharmacology is to offer a risk and benefit assessment of the effects of drugs on patients by conducting studies providing an estimation of how effective the drugs are on large groups of individuals and/or evaluating also any bad effects on large groups of users.

It is also the name of a sub-specialty of epidemiology that involves evaluating drug benefits amid large groups of people.