active ingredient: Definition, Uses, and Clinical Overview
An **active ingredient** is the component in a product that is intended to create a specific biological or functional effect. In skincare, it often refers to ingredients that target concerns like acne, pigment, texture, or aging changes. In medical settings, it can describe the drug or agent responsible for the therapeutic effect (topical, injectable, or procedural). It is used across **cosmetic** care and **reconstructive** care, depending on the product and clinical goal.