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Howick J, Bishop F L et al. PLoS ONE 2013; 18: e58247. doi:10.1371/journal.pone.0058247

How often does a dentist prescribe a mouthwash for ambiguous symptoms (impure placebo), or even carry out a 'sham' adjustment of a removable prosthesis (pure placebo)? Also described in this paper is a nocebo. Merriam-Wester states a nocebo is a harmless intervention that is nevertheless associated with 'adverse effects due to negative expectations'. An example would be the provision of a stabilisation splint for tinnitus. In this study, 783 UK general medical practitioners (from 1,715 invited) completed a web-based questionnaire. Seventy-seven percent of practitioners used impure placebos and 1% used pure placebos, at least once a week. However when a placebo is used, invariably the patient is not afforded the moral imperative and legal right to give real consent. The implications of the final sentence 'Further investigations are warranted to develop ethical and cost-effective placebos' require careful examination.