For a short answer, scroll down to “summary”. Continue reading for a more detailed explanation.
Personally, as a medical doctor and a clinical researcher, as well as someone who has observed Reiki in action for over a decade, I have enough observational evidence to be certain that Reiki is indeed effective for a wide range of indications, and even though I have not statistically analyzed the observational data, I am also certain that the effectiveness goes beyond the placebo effect.
However, my information is based on my own observations, and it will not, and cannot be accepted by the scientific community as proof of Reiki effectiveness, since this type of evidence has a very low weight in the hierarchy of scientific research. If on the other hand, I were to conduct a multi-center placebo-controlled, reproducible clinical trial, then its results may count for something.
In general, in order to demonstrate the effectiveness of any treatment modality for any indication, it takes multiple well-designed, high quality clinical trials per indication. (An indication means the specific issue we are trying to study and address. For example, if we are studying whether or not Reiki is effective for headaches, headaches would be an example on an indication.)
To conduct high quality research in Reiki takes lots of time and money, well-trained staff (in Reiki, and in how to be a practitioner in a clinical trial), high quality study design, proper statistical analysis, and so on. The combination of all of these and other factors is at the core of a high quality clinical trial that can produce valid results. Many high quality trials are needed, so that they can be eventually analyzed together, to convince the scientific community that a particular healing modality (Reiki, a specific medication, etc.) is indeed effective for something.
As of now, there have been numerous studies of Reiki effectiveness, and although some of the studies do show some effectiveness, overall, at this point, given the limitations and current low level of Reiki research, from a medical/scientific perspective, when the available studies have been analyzed, Reiki has been found to be neither harmful nor helpful.
This does not mean that Reiki does not work. It only means that given currentresearch, we can only conclude that it is not harmful (great news for Reiki recipients and practitioners), and we cannot conclude at this point that it is effective (OK news, considering limitations of the available clinical trials). This means that based on the available clinical evidence, a medical doctor will generally neither recommend, nor deter patients who seek Reiki treatment from getting it.
This viewpoint on the effectiveness of Reiki might appear nearsighted from the perspective of the Reiki community; however, if we want scientific proof, then we have to accept that individual Reiki experiences, no matter how plentiful and how remarkable, are not enough. It will take a lot of high quality research to get the scientific proof that’s acceptable to the scientific community. The good news is that if and when better evidence of Reiki effectiveness is available, the scientific community will accept it and will even recommended it.
We are not there. Yet.
Below are some of the obstacles to demonstrating Reiki effectiveness scientifically:
More high quality research is needed in order to determine whether or not Reiki is effective with a high level of scientific certainty, and beyond individual experiences and observations.
Disclaimer: I am replying to this question from a scientific point of view and not from the Reiki point of view.