I am doing preliminary research for a job interview as a Clinical Research Nurse Coordinator. I have experience as a bedside nurse in the hospital. We see people for 1-2 days. If I give a medication (usually a narcotic or antibiotic), it is fairly clear to me if the patient is having a normal "side effect" or something more serious like an allergic reaction. Here is my question: in a clinical research study (esp. with chemo drugs) the side effects can be profound. In Keytruda alone, the side effects can include severe organ damage. So in reporting issues, at what point do you determine if someone is having a normal, expected side effect versus an adverse drug reaction or event? Is it severity? In my research, there seems to be some confusion as to the terms side effect and adverse drug reaction. Thanks!