Which of the following best describes "tolerance" in substance use?

Tolerance in the context of substance use is best described as needing more of a substance to achieve the same effect. This phenomenon occurs as the body adjusts to the presence of the drug over time, leading to a decrease in its effectiveness at usual doses. As individuals continue to use a substance, their physiological and psychological responses can change, resulting in the need for larger quantities to experience the same effects previously felt with lesser amounts.

Increased sensitivity to a drug, withdrawal symptoms, and quitting the substance without adverse effects relate to different aspects of substance use and addiction. Increased sensitivity would imply that a person reacts more strongly to a drug, which is the opposite of tolerance. Withdrawal symptoms indicate a physical dependence on the substance, and quitting without adverse effects suggests that a person might not have developed a dependency or tolerance to the substance in the first place. Hence, the definition of tolerance is specifically tied to the increased quantity of substance required to achieve prior effects.