Which of the following best describes drug dependence?

The concept of drug dependence encompasses a physical need for a substance due to changes that occur in the body as a result of continued use. This physical dependence manifests itself in the form of withdrawal symptoms when the drug is not taken, which can range from mild discomfort to severe health complications. Thus, when someone is physically dependent on a drug, their body has adapted to its presence, and the absence of the drug can lead to a range of uncomfortable and often dangerous symptoms.

While psychological cravings are a significant part of drug dependence, they tend to stem from the physical dependence. Similarly, tolerance, or resistance to drug effects over time, is another factor associated with dependence but does not fully encompass the comprehensive nature of the term as it relates to the necessity to avoid withdrawal symptoms. Lastly, casual use of prescription medication does not imply dependence; dependents typically have an ongoing and problematic relationship with the substance.

Understanding this definition helps clarify the severity and complexity of drug dependence, illustrating its primary focus on the body's physical needs and the experiences tied to withdrawal.