Adverse drug reactions are that unwanted or harmful reaction which is experienced after the administration of a drug or combination of medicine under normal conditions of use. Adverse drug reactions embrace rashes, jaundice, anemia, a decrease in the white white blood cell count, kidney damage, and nerve injury that will impair vision or hearing. Affected people are also allergic or supersensitized to the drug owing to genetic variations in the way their body metabolizes or responds to medicine. A serious adverse reaction means an adverse reaction which is fatal, life-threatening, disabling, incapacitating, or which results in or prolongs hospitalization. An ADR may result from both drug related factors such as drug effects, drug use, synergistic effects between a drug and a disease or between two drugs & also non-drug related factors like abnormal pharmacokinetics due to genetic factors, age or disease states. Pharmacovigilance is an essential activity since clinical trials do not always involve large enough samples of patients and these patients are not normally treated for a sufficiently long period of time to guarantee the detection of all the adverse effects of the medication undergoing the study.