Abstract

This article concerns the ambiguity of the placeboconcept. It contains knowledge about the healingpotential of the placebo effect with special atten-tion to dermatology, and discusses the relationship be-tween complementary and placebo therapy. Background Until the beginning of this century, the effects of most treatments were largely due to the placebo effect.1–3 Nowadays, doctors only seldomly prescribe pure pla-cebos.4,5 Still, even in modern, scientifically based med-ical and dermatological therapies, the therapeutic ele-ments behind the placebo effect have a very important role to play. There are only a few guidelines, however, about how to make the therapeutic elements of the placebo effect function. Their mechanisms are poorly understood, and very little is known about their healing potential. The main reason is the untreated control group is almost never included in trials. Only 12 trials with an untreated control group have been found in a search of the treat-ments of all diseases6 and only three trials on skin diseases.7–9 Thus, most reports of observed placebo ef-fects are confounded by artefacts including spontane-ous remission.6 A major reason for this methodologic error is that the word “placebo ” is used with very different meanings. It has even recently been claimed that the placebo concept as presently used cannot be defined in a logically con-sistent way.10 Therefore, I am forced to start with the rather heavy task of thoroughly examining the placebo concept. This will also lay the groundwork for an un-derstanding of the problems that arise when the pla-cebo concept, despite its ambiguity, only too often is given a central role in discussions about complemen-tary therapy.