What is meant by "systemic effect" in pharmacology?

"Systemic effect" refers to the impact a medication has on the entire body, as opposed to only affecting a localized area. When a drug produces a systemic effect, it enters the bloodstream and influences multiple systems or organs throughout the body. This is particularly important when considering various routes of administration, such as oral or intravenous, which facilitate the medication's widespread distribution.

In contrast, a localized effect would mean the medication acts only where it is applied without significant influence on the rest of the body. The definition of systemic thus highlights the comprehensive nature of the impact, often resulting in therapeutic benefits or side effects that are experienced throughout different body systems. Understanding this concept is essential for recognizing how medications can have both intended and unintended effects beyond their immediate application site.