Written by Helen Seers, Edzard Ernst and the CAM-Cancer Consortium.
Updated 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 client 1,2. 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” blocks 3. 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 patients, e.g.4,5. Most authors claim it is commonly used by cancer patients,e.g. 3,4. Other data, however, suggest that Reiki use is rare 6. In the UK, 43% of those cancer-units which offer some form of CAM also provide Reiki as a supportive or palliative therapy 7.

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.


Helen Seers, Edzard Ernst, CAM-Cancer Consortium. Reiki [online document]. http://cam-cancer.org/The-Summaries/Mind-body-interventions/Reiki. June 10, 2017.

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.


  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.