A placebo is a dummy treatment in a placebo controlled trial, in which at least two different products are compared. One group of subjects will receive the new drug being tested; while the other group will receive an inactive substance designed to resemble the actual drug. Not in every clinical trial a placebo is used as a reference.

By comparing people’s responses to the drug being tested and to the placebo, the real benefit of the new drug is measured and not the normal course of the disease or the psychological response. In the case of life-threatening diseases, placebos are usually not used.