A placebo is a medicine or treatment intended to appear genuine, but actually have no pharmaceutical effect, such as inert sugar pills. The placebo effect is a genuine psychobiological phenomenon in which the mere expectation of improvement from a placebo can lead to some actual physiological changes. Modern studies find that placebos can affect some outcomes such as pain and nausea, but otherwise do not generally have important clinical effects. There is also the effect called a nocebo effect. The nocebo effect is falling ill simply by consciously or subconsciously anticipating a harmful event. Both placebo and nocebo effects are presumably psychogenic but can induce measurable changes in the body.