Define the term adverse drug reaction (ADR).

An adverse drug reaction (ADR) is specifically defined as an unwanted and harmful reaction that occurs following the administration of a drug. This definition captures the essence of adverse effects that go beyond the desired therapeutic outcomes of medication. ADRs can range from mild side effects to severe and life-threatening conditions, making it crucial for healthcare professionals to identify and manage them effectively.

In this context, it is essential to distinguish ADRs from other concepts. For instance, beneficial effects resulting from drug administration highlight the positive outcomes, which do not align with the definition of an adverse reaction. Additionally, predictable outcomes from drug tolerance refer to the body's adaptation to a drug over time, leading to diminished effects, which again does not pertain to harmful or unwanted reactions. Lastly, while drug interactions can lead to adverse effects, they do not explicitly define an ADR but rather represent a broader category of potential complications from medication use.

Understanding ADRs is vital for patient safety and can guide healthcare providers in making informed decisions about prescribing medications, monitoring patients, and educating them about possible risks associated with their treatment.