The placebo effect is the effect that can be observed by taking a treatment that does not contain any active ingredients. This placebo effect, which is partly attributed to the feeling of well-being that comes from taking a drug, can sometimes be relatively spectacular, with improvements of the order of 30%. In general, this effect diminishes within a few weeks. It is for this reason that the new drugs tested in lupus must be compared to a molecule that has no active ingredient and is called a placebo.