In order for physicians and other healthcare practitioners to recommend a treatment or healing practice to patients, they need evidence that it is safe and effective. With respect to safety, there have been no reported negative effects from Reiki in any of the research studies. This is understandable given that no substance is ingested or applied to the skin, and Reiki touch is non-manipulative (and can be offered off the body when needed).
Is Reiki effective?
That leaves the question: is Reiki effective? Or more precisely, from a research perspective, what is Reiki effective for?
A Reiki practitioner would answer that question by saying, "Reiki is effective for restoring balance, which can show up in a number of ways, depending on the current need of the individual." That's not an answer that appeals to medical researchers, who are used to studying treatments for specific illnesses rather than treatments to promote wellness or restore balance.
Respected medical research is designed to address very specific questions. Although conventional medicine has long included a concept of homeostasis, or systemic balance, there has historically been no clear definition of this concept that can be used to test the hypothesis that Reiki promotes balance. Given the vagueness of the term stress and the differences in human bodies and the circumstances in which they live and function, how would science measure an individual's balance?