placebo

placebo , inert substance given instead of a potent drug . Placebo medications are sometimes prescribed when a drug is not really needed or when one would not be appropriate because they make patients feel well taken care of. Placebos are also used as controls in scientific studies on the effectiveness of drugs. So-called double blind experiments, where neither the doctor nor the patient knows whether the given medication is the experimental drug or the placebo, are often done to assure unbiased, statistically reliable results. A traditional placebo's lack of side effects, however, often identifies it, so an older drug is sometimes used in drug tests instead of or in addition to a placebo.

The "placebo effect" is an apparent improvement in health due not to any treatment but only to the patient's belief that he or she will improve (as by taking a dummy pill that is thought to be a cure). A report released in 2001, however, reviewed 114 studies where use of a placebo was compared to both treatment and no treatment and found no placebo effect with respect to measurable medical conditions, such as blood pressure and cholesterol levels. An opposite, or "negative placebo effect," has been observed when patients believe their health will get worse.

placebo a pill, medicine, or procedure prescribed more for the psychological benefit to the patient of being given a prescription than for any physiological effect.

placebo A treatment which has no effect, and is administered to a control group in experimental research, in place of a treatment whose effects are being studied. This usually happens only in medical research; in social research, control groups are rarely offered a placebo experience or treatment.

In the medical context, a substance lacking known pharmacologically active ingredients is given to the sick in order to please them; that is, for possible beneficial effects arising from faith in the powers of treatment (the placebo effect). Placebos are also widely used as controls in evaluating the therapeutic efficacy of the active components of new drugs. Conventionally, the experimental treatment is given to cases selected at random, with the ineffective placebo given to all other cases, even though they are suffering from the same illness. In the ‘double blind’ situation, even the person administering the treatments does not know which is which, as the medicines are made to look the same, to prevent him or her inadvertently communicating their knowledge to recipients.