Definitions, effects, and ethics

A placebo has been defined as "a substance or procedure… that is objectively without specific activity for the condition being treated". [ 20 ] Under this definition, a wide variety of things can be placebos and exhibit a placebo effect. The placebo effect may be a component of pharmacological therapies: Pain killing and anxiety reducing drugs that are infused secretly without an individual's knowledge are less effective than when a patient knows they are receiving them. Likewise, the effects of stimulation from implanted electrodes in the brains of those with advanced Parkinson's disease are greater when they are aware they are receiving this stimulation. [ 21 ] Sometimes administering or prescribing a placebo merges into fake medicine.

The placebo effect has sometimes been defined as a physiological effect caused by the placebo, but Moerman and Jonas have pointed out that this seems illogical, as a placebo is an inert substance that does not directly cause anything. Instead they introduced the term "meaning response" for the meaning that the brain associates with the placebo, which causes a physiological placebo effect. They propose that the placebo, which may be unethical, could be avoided entirely if doctors comfort and encourage their patients' health. [ 18 ] Ernst and Resch also attempted to distinguish between the "true" and "perceived" placebo effect, as they argued that some of the effects attributed to the placebo effect could be due to other factors. [ 22 ]

The placebo effect has been controversial throughout history. Notable medical organizations have endorsed it, [ 23 ] but in 1903 Richard Cabot concluded that it should be avoided because it is deceptive. Newman points out the "placebo paradox", – it may be unethical to use a placebo, but also unethical "not to use something that heals". He suggests to solve this dilemma by appropriating the meaning response in medicine, that is make use of the placebo effect, as long as the "one administering… is honest, open, and believes in its potential healing power". [ 14 ]