An Adverse Drug Reaction (ADR) is an unwanted or harmful response to a medication that occurs at normal doses. These reactions can range from mild side effects, like nausea or dizziness, to severe complications, such as allergic reactions or organ damage. ADRs can happen to anyone, regardless of age or health status, and may be influenced by factors like genetics, other medications, or existing health conditions. Monitoring and reporting ADRs are crucial for patient safety. Healthcare professionals often use systems like the FDA's MedWatch to track and analyze these reactions. Understanding ADRs helps improve medication safety and guides doctors in prescribing the most effective treatments for their patients.