Which term means resistance to the action of a drug, requiring a larger dose to achieve the same effect?

• A. Side effect
• B. Trade/Brand name
• C. Tolerance
• D. Generic name

Answer: (C)

Tolerance is when the body becomes less responsive to a drug after repeated use, so a larger dose is needed to achieve the same effect. This happens as the body adapts—receptors may become less responsive or fewer in number (pharmacodynamic tolerance), and enzymes may metabolize the drug more quickly (pharmacokinetic tolerance). It’s distinct from side effects, which are unwanted effects at normal doses, and from naming terms like brand or generic names. In practice, tolerance can lead to dose increases and requires careful monitoring, documentation, and possible adjustment of therapy to avoid ineffective treatment or escalation.