Placebo-Controlled Trials, Ethics of

There are often good scientific and ethical reasons for using placebo controls in clinical trials. At the same time placebo use is controversial, especially when an established effective treatment is being withheld from the control group. This article gives an overview of the key ethical positions in the controversy around placebo-controlled trials. While some argue that placebo controls can only be used when withholding or delaying an established effective treatment poses no or negligible risks to participants, others hold that the risks should be low or acceptable in light of the social value of the knowledge to be gained from the research. The article also describes different positions on placebo use in trials in low- and middle-income countries where study participants may not have had access to an established effective treatment outside the trial.