A therapeutically inert substance given to see whether it results in changes in symptoms. Placebo use is most common in clinical research studies, most often those testing investigational new drugs. Placebo controls, as this approach is called, allow researchers to measure and quantify responses and present them as comparable comparisons when objective measurement is difficult. If, for example, 5 percent of those who take an investigational new drug report that muscle aches diminish but 5 percent of those who take the placebo make the same report, the effectiveness of the investigational new drug is questionable. If, however, 30 percent of those taking the drug being tested make such a report compared to 5 percent taking the placebo, and the investigational group has been well designed (for example, is large enough), the difference is statistically significant and becomes a factor supporting the investigational new drug’s effectiveness.
The ethical issue for researchers, and a critical health issue for research study participants, in PLACEBO-controlled research studies is to make sure that administration of the placebo does not jeopardize the person’s health or well-being because in general it is unethical to withhold treatment with an effective substance for a significant amount of time. A person considering participation in a clinical research trial should make sure to understand fully whether placebo controls are being used and what this means in terms of other possible treatment options.
Some controversial trials of surgical methods have involved placebo surgery in which the surgeon makes a small incision in the skin and gives the appearance of conducting surgery but does not. The ethical issue here is that the placebo surgery is nonetheless invasive even though it has no therapeutic effect and exposes the person to the risk, however slight, of infection, bleeding, and other complications.
There is a phenomenon called the placebo effect in which the person’s belief that a substance is providing relief causes him or her to perceive that relief occurs. Even the symptoms of Parkinson’s disease are at least in the short term somewhat amenable to this effect as they are often susceptible to subconscious control.