Placebos are used in clinical trials to demonstrate that an experimental drug is superior to the control or “inactive” pill, but sometimes placebos can contain “excipients” such as chemicals, dyes, allergens, or other confounding agents, which might unintentionally bring about symptoms in trial participants. Maryanne Demasi, Ph.D., discusses the issues that arise when placebos are not inert and how these issues may be addressed by the medical journals publishing trial results.