Placebo-controlled trial
In a placebo-controlled trial, some people get the real medicine and some get a look-alike with no active drug, and usually nobody knows who got which until the end. Comparing the two groups shows what the medicine itself does. It helps separate real effects from the effects of simply expecting to feel better.
For experts
In a placebo-controlled trial, subjects are randomly assigned to the test treatment or to an identical-appearing treatment that does not contain the test drug, and such trials are almost always double-blind (ICH E10). The design controls for the placebo effect, but ICH E10 notes this is not its only or major benefit: by allowing blinding and randomisation and including a group that receives an inert treatment, it controls for influences on the course of disease other than the drug's pharmacologic action, such as natural history, expectations and regression to the mean. A placebo control group is not necessarily an untreated group, since placebo and the new treatment may each be added to standard therapy.
Sources (2)
- 01ICH E10: Choice of Control Group and Related Issues in Clinical TrialsInternational Council for Harmonisation (ICH) · 2000-07-20 · accessed 2026-09-29
- 02Step 3: Clinical ResearchU.S. Food and Drug Administration · 2018-01-04 · accessed 2026-09-29