Which term describes a combination of two drugs causing a greater effect than the sum of their individual effects?

• A. Side effect
• B. Synergistic action (Synergism)
• C. Tolerance
• D. Toxicity

Answer: (B)

Two drugs producing a greater effect than the sum of their individual effects is called synergism. This happens when the drugs interact to amplify each other’s actions, often by hitting different targets or pathways that enhance the overall response, or when one drug increases the effective concentration of the other. Because the combined effect exceeds simple addition, it represents a true enhancement of therapeutic impact rather than just an additive effect. This concept differs from a side effect (an unintended adverse effect), tolerance (a diminished response with repeated dosing), or toxicity (harmful effects from too high a dose). Synergism can improve efficacy and allow lower doses, but it also requires careful monitoring to avoid excessive effects or adverse reactions.