Differentiate between adverse drug reaction and side effect.

• A. A side effect is predictable, often mild at standard doses; an adverse drug reaction is harmful or unintended.
• B. An adverse drug reaction is predictable and mild at standard doses.
• C. A side effect is harmful and unpredictable.
• D. All adverse drug reactions are dose-related.

Answer: (C)

Understanding the difference: a side effect is a secondary effect of a drug that is expected and usually predictable, often mild at standard doses. An adverse drug reaction is a harmful or unintended response to a drug that can occur at normal doses and may be unpredictable or more serious. Therefore, the best description is that a side effect is predictable and often mild at standard doses, while an adverse drug reaction is harmful or unintended. The other statements misstate the relationship by implying all ADRs are predictable or mild, or that side effects are always harmful and unpredictable, or that ADRs are always dose-related.