The term used is “placebo.”

Quick Scoop

In clinical trials, a placebo is a substance that looks like the real drug (same appearance, taste, and form) but has no active therapeutic ingredient. Researchers give a placebo to some participants so they can fairly compare outcomes against those who receive the actual investigational drug.

This helps distinguish the real effect of the drug from the “placebo effect,” where someone feels better simply because they believe they are being treated.