Clinical Research Glossary

antagonistic effect antagonistic effect

CDISC

When one treatment or intervention works against another to reduce or block its effect.

Example of antagonistic effect in a sentence

An antagonistic effect means that one thing is lowering the effect of another.

More Info

An antagonistic effect is an example of how medicines interact with each other.

An antagonistic effect occurs when one substance or study treatment goes against the effect of another one. This can have a positive or negative impact.

For example, a medication that causes blood thinning could potentially be countered by taking Vitamin K, which has a clotting effect.

Another example for antagonistic effect is when a treatment is taken to reduce the side effects of another treatment. This is an overall positive outcome for the person taking these two treatments.

Other info to think about when joining a study

The term “antagonistic” is sometimes used to describe how two things that are used together actually have a weakened effect than when just one of them is used alone. It’s like the two things work against each other to have less of an effect.

You may want to find out more about why the two treatments work against each other and whether that effect is a good thing or a bad thing for you. You might also want to know if it is possible to modify or reverse the effect.

Version 4.0 September 2026

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