What does "adverse reaction" refer to in pharmacology?

In pharmacology, "adverse reaction" specifically refers to an unexpected or harmful effect that arises from the use of a medication. These reactions can occur despite proper usage and administration of the drug, indicating a deviation from the intended therapeutic outcomes. Adverse reactions can range from mild side effects to severe, life-threatening responses, and recognizing them is crucial for ensuring patient safety and effective medication management.

For instance, if a medication is designed to lower blood pressure but unexpectedly causes severe dizziness or an allergic reaction, these would be classified as adverse reactions. Understanding the potential for these effects allows healthcare professionals to monitor patients closely, adjust dosages, or even discontinue use when necessary to prevent harm.

In contrast, the intended positive effects of a medication are the primary therapeutic outcomes that medications are developed to achieve, whereas the usual body response refers to the expected reactions that typically accompany the administration of a drug. A legally defined reaction relates to specific regulatory considerations around controlled substances but does not capture the broader concept of adverse reactions.