How is a drug defined in the context of substance use?

A drug is defined as any substance that, when ingested or introduced into the body, can change its physiological or psychological functions. This wide-reaching definition encompasses a variety of substances, including legal and illegal drugs, over-the-counter medications, and prescription drugs.

Understanding this definition is crucial in the context of substance use, as it highlights that both legal substances, like alcohol or caffeine, and illegal substances can have significant effects on the body and mind. This perspective allows counselors and professionals in the field to consider a broader range of substances and their potential impacts on individuals, rather than being limited to only illegal or habit-forming substances.

The other options focus too narrowly on specific categories or types of substances, which may overlook the bigger picture of how various substances can alter body functions regardless of their legal status or potential for addiction. By recognizing that any substance can have an effect, practitioners are better equipped to address various issues related to substance use and develop comprehensive treatment strategies.