Pharmacoepidemiology is that the study of use and effects of medication among the massive range of individuals. The term Pharmacoepidemiology involves both the pharmacology and epidemiology. The pharmacology is related to the effect of drugs in humans, while epidemiology deals with the factors which determine the occurrence and distribution of diseases in population. It provides an estimation probability of useful effects of a drug in adverse effects and in population. Pharmacoepidemiology concentrates on clinical patient outcomes from medical specialty by victimization ways of clinical medicine and applying them to understand the determinants of useful and adverse drug effects, results of genetic variation on drug effect, duration-response relationships, clinical effects of drug-drug interactions, and therefore the effects of medication non-adherence. Pharmacovigilance may be a part of pharmacoepidemiology that involves continual observation, in a very population, for unwanted effects and alternative safety considerations arising in medicine that are already on the market. Pharmacoepidemiology typically conjointly involves the conduct and analysis of programmatic efforts to boost medication use on a population basis.