What does tolerance refer to in relation to drug use?

Tolerance refers to a physiological response that occurs when an individual uses a drug repeatedly over time. As tolerance develops, the body becomes accustomed to the presence of the drug, which often leads to a diminished response to its effects. In other words, a person may require a higher dose of the drug to achieve the same effect that they initially experienced with a lower dose. This phenomenon is a common aspect of substance use and can significantly impact an individual's relationship with the substance, potentially leading to increased consumption and risk of dependence.

The other options describe different concepts related to drug use but do not accurately define tolerance. Increased effectiveness refers to a change that does not typically occur with repeated drug use, as tolerance usually involves a decrease rather than an increase in drug effectiveness. Immediate dependence relates to a different aspect of drug use, focusing on psychological or physical reliance on the substance rather than the body's somatic adaptation to its continuous presence. Resistance to withdrawal symptoms implies an adaptation in response to cessation of drug use, which is a distinct concept from tolerance itself.