Clinical Research Glossary

synergistic effect synergistic effect


When two or more things used together have a greater effect than each thing alone.

Example of synergistic effect in a sentence

A synergistic effect means that a combined product has a stronger effect than what would be expected.

More Info

A combination of medications is synergistic if they work better together than if the individual component effects were added together.

For example, Drug A decreases cancer growth by 10% and Drug B by 20% when each are used alone. One would predict that used together, cancer growth might be decreased by 30% (additive). If Drug (A + B), used together, decreases cancer growth by greater than 30% (say 35% or more), the effect is synergistic.

Other info to think about when joining a study

The term “synergistic” is sometimes used to describe how two things that are used together actually have a greater effect than just one of them used alone. It’s like the two things work in synergy with each other to have more of an effect.

You can ask the study team if you have any questions about the word “synergistic” is being used in study documents or conversations you are having.

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