Arzneimittel Forsch
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Arzneimittel Forsch · May 1999
ReviewPlacebo--efficacy and adverse effects in controlled clinical trials.
The therapeutic efficacy of placebo in a series of diseases has long been known. It is less well known, however, that treatment with placebo can also produce significant adverse drug reactions. Therefore, the placebo drug reactions from controlled trials were studied for the first time systematically. ⋯ Treatment with placebo is frequently effective and cannot therefore be considered as "non-treatment". Placebo effects can only be quantified by direct comparison with "non-treatment". Like active treatment, treatment with placebo is frequently accompanied by adverse drug reactions. Placebo adverse effects are often disease- and active treatment-specific. The effects and adverse effects of a placebo need to be known before the effects of active treatment in controlled clinical trials can be assessed. The mechanisms of placebo effects are many and varied (e.g. endorphin release, conditioning). Since the use of drugs without regard to evidence-based medicine (prescription of drugs without proven efficacy = pseudoplacebos) may clearly also result in serious adverse effects, such practice may not only be non-beneficial but may even be harmful.