Placebo

A placebo is any medication or treatment expected to have no physiological effect; the generally synonymous term sham treatment is sometimes used to describe a surgical or other procedure, more visible than a pill. Placebos originally were medicinal preparations having no specific pharmacological activity against a targeted condition. They have been used as a means of suggestion to individual patients, but their more common use is as a control arm of a randomized controlled trial.

The World Medical Organization's interpretation of the Declaration of Helsinki, says placebo controls are unethical if there is a standard treatment for the disease being studied. When no treatment is available, placebo controls are ethical. This is by no means agreed by all medical scientists.