The adverse drug reaction monitoring and reporting are very important in identify and preventing adverse drug reaction. The utmost important area during the therapy of patient is pharmacovigilance and it was not implemented in India by health care professionals. The observation of adverse drug reaction during the treatment helps to eliminate the drug induced diseases and death. Hence, this study aimed to estimate the incidence of adverse drug reactions causing hospital admission or occurring while in hospital. It is a prospective Cohort study of six months where the subjects have been followed-up and the outcomes are recorded. The maximum number of adverse drug reaction reported from the general medicine department was 26.66%. The geriatric patients had experienced more adverse drug reaction, accounting for about 44.90% followed by adults 34.90% and children 20.40%. The reason for geriatric falls in adverse drug reactions may be the alterations in Pharmacokinetic parameters, multiple drugs and polypharmacy.