How can adverse drug reactions (ADRs) be characterized?

Adverse drug reactions (ADRs) can be characterized as undesirable effects from medication use. This definition encompasses any harmful or unintended response that occurs when a person is administered a drug, which may lead to varying degrees of severity. ADRs can arise from various reasons, including patient sensitivity to a drug, interactions with other medications, or even the pharmacological effects of a medication itself. Recognizing ADRs is critical in the clinical setting to ensure the safety and effectiveness of drug therapy.

In contrast, the other options refer to different aspects of drug effects. Expected effects of a medication generally denote the therapeutic benefits intended by the prescribing healthcare provider, while side effects that always resolve do not accurately describe the range of ADRs, as some can persist or lead to serious health consequences. Furthermore, effects that enhance the efficacy of a drug do not align with the definition of an adverse reaction, as they imply a beneficial outcome rather than an undesirable one.