Placebo any substance that is a component of the active substance (active ingredient) such as flour, sugar preparation to form the same drug. It is used to treat some friends or a control group (control) in the comparative study of efficacy in the hope of reducing bias in interpreting the results of treatment. Or to have hope in the treatment of heart related condition such that the placebo effect is 18-67% and 7-19% in anxiety disorders in patients with obsessive-compulsive symptoms