Reiki | Cam-Cancer


Abstract and key points
  • Reiki is often classified as a form of energy healing.
  • Its mechanism of action is not biologically plausible.
  • The few clinical trials that have been published have shown some effects of Reiki on improving cancer related symptoms; however conclusions are limited due to methodological shortcomings of the studies.
  • Reiki has not been associated with serious risks.

Reiki, a form of energy healing that originated in Japan, is a system of natural healing administered by the laying on of hands and by transferring energy from the Reiki practitioner to the recipient. It is sometimes used as a palliative or supportive treatment of cancer patients. Only few studies of Reiki have been published; most have methodological limitations and are thus not conclusive. Reiki is not believed to have the potential to cause serious direct harm.

Document history

Summary fully updated and revised in June 2017 by Helen Seers
Summary fully updated and revised in March 2015 by Helen Seers.
Summary fully updated and revised in March 2013 by Edzard Ernst.
Summary first published in July 2011, authored by Edzard Ernst.


Helen Seers, Edzard Ernst, CAM-Cancer Consortium. Reiki [online document], June 10, 2017.

What is it?


Reiki is a form of energy healing originating from Japan where it was developed and promoted by Mikao Usui, a Buddhist monk in the early 20th century. The Reiki practitioner uses light touch and believes to channel Reiki “energy” into the patient or client1,2. Reiki can be practised by anyone with different degrees of training and expertise.

Application and dosage

The Reiki-practitioner either uses light touch or heals at a distance by sending Reiki-‘energy’ to the patient. The term is in inverted commas because it is not energy in the sense science would define it. Therapy can be as often as desired, typically several times per week. A course of treatment might consist of 6 or more sessions and is determined by the preferences or needs of the patient and the practitioner. Reiki is usually used in addition to conventional therapies in any setting.


The Japanese theologian Mikao Usui is said to have rediscovered the technique in the late 19th century. Apparently it has its roots in ancient Tibetan Buddhism. Providers are initiated by an experienced Reiki-master up to three levels of attunement.

Claims of efficacy

The Reiki-‘energy’ allegedly stimulates ’balance’ and self-healing. Thus Reiki is being used to maintain wellbeing and help the treatment of most human conditions or symptoms, including symptoms related to cancer treatments.

Mechanism of action

Some authors claim that Reiki operates on a physiological level causing molecules within the body to attain higher energy levels. Reiki is said to remove “energy” blocks3. From a more scientific point of view, Reiki's effects have not been documented and its mechanisms are unexplained and biologically implausible.

Alleged indications

Anecdotal evidence suggests that Reiki can alleviate cancer symptoms, such as pain or anxiety. Some advocates would go further and claim that Reiki can influence the natural history of malignancies.

Prevalence of use

In Japan, Reiki has been known for many decades. More recently, it has been more widely used in other countries as well. There are few reliable data to accurately describe its prevalence of use in cancer patients4,5. Most authors claim it is commonly used by cancer patients3,4. Other data, however, suggest that Reiki use is rare6. In the UK, 43% of those cancer-units which offer some form of CAM also provide Reiki as a supportive or palliative therapy7.

Legal issues

In most countries, Reiki-practitioners are not regulated healthcare professionals. Anyone regardless of education, training or experience, can claim to be a Reiki-practitioner or Reiki-master. In some countries, e.g. the UK, Reiki-practitioners are not allowed to claim to cure cancer.

Cost and expenditure

Some Reiki-practitioners do not charge for treatments, but in the UK most would ask for around €60 per session.

Does it work?

Systematic reviews

No systematic review specifically looking at Reiki and cancer exists. The included reviews look at Reiki across all diseases, or a more general term for Reiki known as “energy healing”.

Lee et al. (2008)  published a systematic review of 9 RCTs of Reiki as a treatment for any condition including cancer for which trial data were available (results were not separated by condition)8.  Overall results suggested that there was insufficient evidence that Reiki is effective for depression, pain, anxiety, stress and helplessness. Most of these studies had serious methodological limitations.

Another systematic review (2011) of various types of energy healing specifically for cancer included 6 quantitative and two qualitative studies and arrived at very similar conclusions: “The existing research does not allow conclusions regarding the efficacy or effectiveness of energy healing”9.

A recent, (2014) non-systematic review which calculated the overall effect of Reiki for pain and anxiety for all health conditions, including cancer, found four randomised controlled trials where Reiki may be beneficial in reducing pain and anxiety10.  However, this review concluded that more high quality research with larger sample sizes, standardised treatment protocols and consistent randomisation are needed.  This review was also not specific to cancer and included non-cancer trials in its overall conclusion.

Clinical trials

Since the publication of these reviews a further four controlled trials in cancer patients have become available.

An RCT randomised 189 cancer patients receiving chemotherapy in three groups: standard care, placebo-Reiki or Reiki11.  The main outcome measures were self-reported comfort and wellbeing. The analyses showed that both Reiki and placebo-Reiki were superior to standard care. This seems to suggest that Reiki is associated with sizable placebo effects but has no specific effects.

Alarcao and Fonseca (2016) presented a RCT of the effects of Reiki on quality of life for patients with blood cancer12. Fifty-eight people were randomly assigned to Reiki and 58 to sham Reiki (control), the interventions were two one-hour sessions per week for 4 weeks.  The methodology of the trial is stated as double-blind, however, no specific details on how the blinding occurred for those giving the Reiki, or receiving it, are given; also the success of blinding is not reported.  Results showed a significant benefit of the Reiki group for general, physical, environmental and social aspects of the WHOQoL Brief measure.  It must be noted that a large number of the control group (n=16) died before the trial was completed, however this attrition occurred after randomisation, and those that died had the worst prognosis – those with the worse prognosis were equally represented in the experimental arm.  Larger sample size testing would be needed to improve the reliability of this trial.

Orsak et al. (2015) conducted a pilot RCT (n=36) on breast cancer patients who received either Reiki, a companion, or usual care during chemotherapy13. Measures of quality of life (FACT B – Functional Assessment of Cancer Therapy: Breast Cancer version) and mood (Profile of Mood States) were found to be better than usual care in the Reiki and companion groups.  This study would have benefitted from an additional sham Reiki condition, also, an increased sample size and blinding participants to their intervention groups would have been desirable.

Demir et al. (2015) reported a pilot CCT (n=18) of the effects of distant Reiki on pain, anxiety and fatigue in patients with cancer compared to a control group of usual care14. Significant reductions in measures of pain, anxiety and fatigue (generated by a VAS numerical rating) were found for the Reiki group, however, the two groups were not comprised of similar sexes of participants and the number of participants was very small.

Is it safe?

Adverse effects

None known


None known


None known


None known

Other problems

None known

  1. Birocco N, Guillame C, Storto S et al. The effects of Reiki therapy on pain and anxiety in patients attending a day oncology and infusion services unit. Am J Hosp Palliat Care 2012; 29: 290-4.
  2. Jonas WB. Mosby's Dictionary of Complementary and Alternative Medicine. St Louis US: Elsevier Mosby. 2005.
  3. Barnett H. The Which? Guide to Complementary Therapies. Which? Books, London. 2002.
  4. Lorenc A, Peace B, Vaghela C et al. The integration of healing into conventional cancer care in the UK. Complement Ther Clin Pract 2010; 16: 222-8.
  5. Pierce B. The use of biofield therapies in cancer care. Clin J Oncol Nurs 2007; 11: 253-8.
  6. Talmi YP, Yakirevitch A, Migirov L et al. Limited use of complementary and alternative medicine in Israeli head and neck cancer patients. Laryngoscope 2005; 115: 1505-8.
  7. Egan B, Gage H, Hood J et al. Availability of complementary and alternative medicine for people with cancer in the British National Health Service: results of a national survey. Complement Ther Clin Pract 2012; 18: 75-80.
  8. Lee MS, Pittler MH, Ernst E. Effects of reiki in clinical practice: a systematic review of randomised clinical trials. Int J Clin Pract 2008; 62: 947-54.
  9. Agdal R, von B Hjelmborg J, Johannessen H. Energy healing for cancer: a critical review. Forsch Komplementmed 2011; 18: 146-54.
  10. Thrane S, Cohen SM. Effect of Reiki therapy on pain and anxiety in adults: an in-depth literature review of randomized trials with effect size calculations. Pain Manag Nurs 2014; 15: 897-908.
  11. Beard C, Stason WB, Wang Q et al. Effects of complementary therapies on clinical outcomes in patients being treated with radiation therapy for prostate cancer. Cancer 2011; 117: 96-102.
  12. Catlin A, Taylor-Ford RL. Investigation of standard care versus sham Reiki placebo versus actual Reiki therapy to enhance comfirt and well-being in a chemotherapy infusion center. Oncol Nurs Forum 2011; 38: E212-E220.
  13. Orsak G, Stevens AM, Brufsky A, Kajumba M, Dougall AL. The effects of reiki therapy and companionship on quality of life, mood, and symptom distress during chemotherapy. J Evid Based Complementary Altern Med 2015; 20: 20-7.
  14. Demir M, Can G, Kelam A, Aydiner A. Effects of distant reiki on pain, anxiety and fatigue in oncology patients in Turkey: a pilot study. Asian Pac J Cancer Prev. 2015; 16: 4859-62.

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