The significance of adverse drug reactions (ADRs) among hospitalized patients particularly fundamentally sick patients conceded in the emergency unit has now turned into a worldwide concern. Albeit numerous clinical preliminaries have been directed on medication treatment in fundamentally sick patients, there are no adequate information on the wellbeing of the medication treatment utilized. The present work is a prospective observational study that was carried out in the ICU department, Benisuef teaching hospital, between August 2015 to December 2016, in which one hundred patients; admitted to the ICU, were enrolled. Patients who experienced drug related problems in the form of ADRs and/or adverse drug-drug interactions (DDIs) were recorded. The ADRs were analyzed regarding the incidence (88%), factors affecting the incidence, characteristics (most of ADRs were moderate, preventable, probable and type "A"). Clinically relevant adverse DDIs were analyzed regarding the incidence, mechanism, causal drugs and management plans.