Placebo response: A positive medical response to taking a placebo, a sham medication as if it were an active medication. Up to one-third of patients given a placebo may respond with a reduction in symptoms, depending on the condition. This phenomena is often laid to patients believing their symptoms have improved when in fact they have not. Evidence is beginning to emerge that actual physiological changes can result from believing that one is receiving medical treatment.

The placebo response is now usally called the placebo effect. For more information, see: Placebo effect.