The placebo effect refers to a therapeutic effect occurring in medicine without the administration of drugs with actual active ingredients. The effect that nevertheless occurs is mainly achieved by the fact that the patients do not know that they are taking a placebo (dummy drug). Treatment by hypnosis is also often regarded as a placebo treatment. However, hypnosis does not use a medical agent, so it is referred to as a "placebo without deception." With hypnosis, it is believed that similar mechanisms of action as with placebos can take effect, and the client's expectations also influence the processes of change and healing.