What defines an adverse drug reaction?

An adverse drug reaction is specifically defined as an unwanted, unintended, and usually harmful effect that occurs when a medication is administered at normal doses. This means that while the medication is intended to provide a therapeutic benefit, it can also produce negative effects that may range from mild to severe. The concept encompasses any negative outcomes that are the direct result of the medication itself, rather than being a result of an overdose or misuse.

The distinction is important because adverse drug reactions can manifest in various ways, including side effects, toxicities, or even severe allergic reactions. However, the key element is that they are reactions that occur during normal therapeutic use.

Understanding this definition helps in recognizing how medications can affect patients differently and emphasizes the importance of monitoring patients for any unexpected effects when they are prescribed drugs.