In medical research, placebos are given as control treatments and depend on the use of measured deception. Common placebos are inert tablets, sham surgery, and other procedures based on false information. However, placebos can also have a surprisingly positive effect on a patient who knows that the given treatment is without any active drug, as compared with a control group who knowingly did not get a placebo.
In one common placebo procedure, however, a patient is given an inert pill, told that it may improve his/her condition, but not told that it is in fact inert. Such an intervention may cause the patient to believe the treatment will change his/her condition; and this belief may produce a subjective perception of a therapeutic effect, causing the patient to feel their condition has improved. This phenomenon is known as the placebo effect.
Placebos are widely used in medical research and medicine, and the placebo effect is a pervasive phenomenon; in fact, it is part of the response to any active medical intervention. The placebo effect points to the importance of perception and the brain's role in physical health. However, when used as treatment in clinical medicine (as opposed to laboratory research), the deception involved in the use of placebos creates tension between the Hippocratic Oath and the honesty of the doctor-patient relationship. The United Kingdom Parliamentary Committee on Science and Technology has stated that: "...prescribing placebos... usually relies on some degree of patient deception" and "prescribing pure placebos is bad medicine. Their effect is unreliable and unpredictable and cannot form the sole basis of any treatment on the NHS. Wikipedia