2026 RN Medication Administration Practice Test – Full Exam Prep

Drug interactions happen when one medication changes how another one works, affecting either how well it works or how safe it is. This change can come from pharmacokinetic factors—like one drug increasing or decreasing the other’s levels by altering absorption, distribution, metabolism, or excretion—or from pharmacodynamic factors, where the two drugs amplify, diminish, or create a new effect together. The important takeaway is that interactions aren’t limited to herbs or to food; any combination of medications can interact. For example, one drug might slow the metabolism of another, raising its level and risk of side effects, or two drugs with similar effects might produce an exaggerated therapeutic or adverse effect. In short, a drug interaction is when one drug alters the effect of another.