Which statement best describes tolerance in substance use?

• A. Tolerance refers to needing more of a substance to achieve the same effect.
• B. Withdrawal refers to the cravings you get after stopping.
• C. Tolerance and withdrawal are the same phenomenon.
• D. Withdrawal occurs only with alcohol.

Answer: (A)

Tolerance happens when repeated drug use leads to a diminished effect, so a person needs more of the substance to achieve the same level of feeling or impact. This reflects the body's adaptations—receptor changes, altered metabolism, or other brain pathway adjustments—that lessen the drug’s response over time. It’s different from withdrawal, which is the collection of symptoms that occurs when use is reduced or stopped after dependence develops. Withdrawal can involve cravings and physical symptoms and can occur with many substances, not just alcohol. So the idea that you must take more to get the same effect is the best description of tolerance.