Homeopathy – Where is the Evidence?

With science based research indicating that homeopathy is effective in both clinical practice and the laboratory, does the lack of a plausible mechanism of action mean that homoeopathy should be considered by the larger scientific community as nothing more than placebo?

A seemingly simple question: Does homeopathy work? The answer to this has stimulated intense scientific debate for decades, with views on the evidence produced varying greatly with the bias of the patient, practitioner, academic and business involved. If homeopathy does works, then where is the evidence?

The answer is more complex than what you would expect from the supposedly objective realm of science. With no clear mechanism of action demonstrated, the general consensus is that “it can’t work, so it doesn’t work”. However, there is interesting and intriguing evidence both in the laboratory and in clinical practice, with high quality research papers indicating an effect greater than placebo [1].

Why is homeopathy different?

Homeopathy makes use of medicines obtained from mineral, plant and animal sources using the principle of ‘like cures like’. Furthermore, the substances are serially diluted (step-by-step), combined with a specific process of shaking (succession) at the end of each dilution step. This process creates the different ‘potencies’, or strength of the medicines, and dilutions of high potency remedies are mathematically calculated to have no molecules of the original substance remaining in the final product. This puts high potency homeopathy in the realm of ‘energy’ medicine, similar to aspects of Traditional Chinese Medicine and Acupuncture.

Both mainstream science and homeopathy agree that the more the substance is diluted, the less toxic it becomes, and thus homeopathy is non toxic and safe to use in any person and any condition. However, with each dilution, the medicine is seen in homeopathy as becoming ‘stronger’ in the ability to stimulate the self-healing mechanisms of the body, where critics argue that this is implausible and that the remedies are often too diluted to have any biological effect.

As a result, any positive trial is therefore automatically assumed as being flawed, often without proper justification, and generally ignored within the majority of the scientific community. It is agreed by most researchers and academics that homeopathy is effective, but this effect must be due to the placebo response.  However, this is a somewhat distorted and biased view, as more than enough evidence is published in respected journals showing support for homeopathy.

A review of the clinical evidence:

Research at Glasgow University in the early 1990’s was set up to show that the placebo response explains the positive homeopathic response. However, after four trials, this notion was rejected and the studies conclusively showed homeopathy was superior to placebo [2-5], with the researchers duly becoming advocates of homeopathy.

In 1991, a comprehensive independent review of 107 trials was published in the British Medical Journal (BMJ) that showed an overall positive trend in outcomes. They concluded that ‘the evidence  presented in this review would probably be sufficient for establishing homoeopathy as a regular treatment for certain indications…based on this evidence we would be ready to accept that homoeopathy can be efficacious, if only the mechanism of action were more plausible’ [6]. This is a sentiment that has continued to echo in the scientific literature.

Studies continued to accumulate, and a 1997 Lancet review of 89 clinical trials showed a favourable overall outcome for homeopathy, even after correction for publication bias. The review stated that ‘results are not compatible with the hypothesis that the clinical effects of homeopathy are completely due to placebo’ [7]. In a subsequent analysis of the same data set, the authors (Linde and colleagues) investigated the influence of methodological quality on study outcome and found that studies with higher-quality scores had less tendency to be positive than those with lower-quality scores [19]. After discarding the lower-quality trials, however, homeopathic treatment remained more effective than placebo – though less strikingly so than in their previous analysis. In both of Linde’s systematic reviews, insufficient evidence was found to draw conclusions about the efficacy of homeopathy for any specific medical condition, but the notion that homeopathy was explained by the placebo effect was not found to be consistent with the results.

By 2006 there were three more large, comprehensive and independent systematic reviews examining the question of whether homeopathic therapies behave like placebo in controlled clinical trials. The results generally favoured homeopathy, with two analyses showing clear positive outcomes [8;9], the third echoing the idea that although there is a positive overall effect, this effect is scientifically implausible [10].

Although this evidence is generally supportive of homeopathy as having effective clinical results, there is insufficient research to determine the effects of homeopathy on individual conditions or remedies. With this said, there have been numerous trials indicating a positive response compared to placebo for numerous conditions, including respiratory tract complaints, middle ear infection, hay fever, asthma, diarrhoea, menopausal symptoms, arthritis, ADHD, chronic fatigue, infertility and sperm quality…and the list goes on [11].

So there seems to be some clinical evidence to accept that homeopathic medications are effective beyond the placebo effect, but the spectre of the lack of a plausible mechanism of action continues to haunt the homeopathic profession.

‘Clear indications exist about clinical effectiveness of homeopathy; homeopathy is effective in uncontrolled practice or versus comparison groups; enough indications exist that “placebo” is an insufficient explanation for the effects of homeopathy. Homeopathy can be similar or better in effectiveness than conventional   treatment and, where it has been studied, it is cheaper in the long run.’

Conclusion of XVIII Symposium of GIRI, 2004

Some of the laboratory evidence:

The dilution (infintesimile principle) of homeopathic medicines has been the target of the main criticism of homeopathy – ‘it can’t work, therefore it doesn’t work’. However, apart from the general success in clinical trials, there is a large body of laboratory evidence to also suggest that the ultra-dilute substances are more than just water.

Research published in the prestigious Annals of the New York Academy of Sciences (1999) suggests that there may be something active in homeopathic medicines after all. Two Italian professors of chemistry conducted over 500 controlled experiments of highly-diluted acid and base substances. They found that 92% of these test solutions had higher than expected heat emanating from them, which should not happen after the original molecules have been serially diluted out of solution. Dr. Vittorio Elia, the lead researcher, asserted, ‘we are setting the basis for a new science: the physics-chemistry of homeopathic water’ [12].

In 2003, the Physica journal published research that further suggested serially diluted substances differ from ordinary water. Using a technique called thermoluminescence, Professor Louis Rey has shown ultra-high dilutions (no molecules of the original solute remaining) of lithium chloride and sodium chloride to be reproducibly different from pure water diluted with itself, with the conclusion that the substances diluted in such a specific manner may cause a permanent change in hydrogen bonding of the water molecules themselves [13].

In 2004, conventional scientific workers from five countries published evidence of ultra-molecular dilutions (homoeopathic dilutions) of histamine ability to inhibit basophil activation “in a reproducible fashion”. It included one study that was blinded and reproduced in four labs, and a second study confirmed the results independently in another three labs [14]. This has re-ignited the debate surrounding the notion of the ‘memory of water’, and certainly lends credibility to the idea that there is more to homeopathic medicines than just pure water.

There has also been some work done on the ability of homeopathic remedies to destroy cancer cells in laboratory (‘test-tube’) experiments. This has culminated in a paper published by a world leader in cancer research, Dr Moshe Frenkel (MD Anderson Cancer Centre), in the International Journal of Oncology (2010). This researched showed the ability of some homeopathic remedies to kill certain breast cancer lines while not damaging healthy cells [15]. Although much work in verifying these results still remains, the results indicate that there is something in this water after all.

Although the laboratory evidence is still inconclusive, hotly debated and incomplete, several independent (non-homoeopathic) professors examined all the published literature on homoeopathy in November 2004, and concluded in their press release that ‘these experiments are conducted in controlled circumstances, with sufficient amount of plants, animals or cells and with a statistically valid treatment. These facts are indisputable, statistically significant and, for some, reproducible, even if it is not possible to explain the obtained results with the molecular paradigm’ [1]…but still there is an unwillingness to pursue this area of research within much of the scientific community.

 ‘When the observed fact does not correspond to a famous theory, the fact has to be accepted and the theory rejected’;

 ‘A theory must be modified to be adapted to nature and not nature to adapt itself to the theory’

 Claude Bernard

(Introduction à la Médecine Expérimentale)

Here is a quick look at some other significant laboratory and animal research results:

  • Various dynamized (homeopathic) medicines were shown to induce cell destruction in selected cancer cell lines [20]
  • Chelidonium 30cH (homeopathic dilution) ameliorated chemically induced liver cancer in mice [21;22]
  • Lycopodium clavatum showed protective action against CCL4-induced liver damage in rats [23]
  • Podophylum has been shown to inhibit adhesion of neutrophils (a specific type of white blood cell) to specially coated micro plates [24]
  • A homeopathic formulation, Traumeel, has been shown to inhibit the production of specific pro-inflammation chemicals by T-cells in culture (inflammation regulating effect) [25]
  • Numerous homeopathic drugs shown to increased oxidative metabolism in cultured cells [26]
  • Ruta 6C shown to increase telomere erosion on spefic brain cancer cells (glioma) [27]
  • High dilutions of interferon and thymic hormones shown to have a therapeutic effect on cellular immunity with a corresponding positive effect on immunodepressed patients [28]
  • Ultra high dilutions of antigens (immune stimulating proteins) showed a specific antibody response [29]
  • High dilutions of aspirin shown to increased coagulative (blood clotting) activity, and that the effect of high concentration of injected aspirin is totally inhibited by a corresponding injection of high dilution aspirin (therefore showing both effects of high dilution substance and the opposite effect as describe by the Law of Similars) [30-33]
  • High dilutions of arsenic shown to increase the elimination of toxic levels of arsenic i a rat [34]

Is homoeopathy effective when applied clinically?

All this research does little to illustrate the benefits on the ground level, where they really matter – so the question becomes: does this translate to real benefits for patients? The answer to this question lies in observational and outcome studies within health care sectors. There are numerous patient benefit studies to illustrate this, but I would like mention just a few.

A total of 3709 chronically ill patients undergoing homoeopathic treatment in 103 homoeopathic primary care practices in Germany and Switzerland were assessed over an 8 year period. This study showed that disease severity decreased significantly between 2 and 8 years. Physical and mental quality of life assessments also increased considerably. The authors, from Charite University Medical Centre, concluded that ‘Patients who seek homeopathic treatment are likely to improve considerably’, and that ‘these effects persist for as long as 8 years’ [16].

An out-patient study at the Centre for Integrative Care at Glascow Homoeopathic Hospital (GHH) illustrates similar benefits obtained from 200 patients typically showing multiple problems, with mixed chronic pathologies and psychological distress. The following summary of this study can be made [17]:

At presentation:

  • 100% had undergone conventional care
  • 97% had seen a specialist consultant for the problem
  • 85% rated the problem as causing major disruption to daily living
  • 67 % had previously needed hospitalisation for the problem

Range of 3-6 months after treatment (94% response rate):

  • 73% had an improvement in the presenting complaint
  • 70% had an improvement in general mood and well-being

Impact on conventional care:

  • 41% reported decreased GP consultations
  • 41% reported decreased use of conventional medicine
  • 53% reported decreased admission to hospital
  • 39% reported decreased out-patient visits

These figures, and similar figures from other studies, show that even after conventional care had proved ineffective, or has a plateau in its effect, patients can be significantly helped by a holistic care approach with an integrative care programme which includes judicious blending a conventional perspective with complementary approaches, including homeopathy [17].

 ‘Many interesting questions not even asked should be prioritized, such as the potential of homeopathy to avoid invasive procedures in children and, in primary care settings, the long-term effect of homeopathy in preventing chronic complications’

Conclusion of XVIII Symposium of GIRI, 2004

 ‘Homeopathic remedies have similar effects to chemotherapy on breast cancer cells but without affecting normal cells’

Dr Moshe Frenkel

(Associate Professor at the University of Texas and the previous medical director of the Integrative Medicine Program at the M. D. Anderson Cancer Centre)

‘…it’s not pseudoscience. It’s not quackery. These are real phenomena which deserve further study’

Nobel Laureate Luc Mantagnier

(received Nobel prize in 2008 for linking the HIV virus to the AIDS epidemic)


Brian Josephson, PhD

(Nobel laureate in 1973 in the field of physics)

The scientific conundrum:

With numerous quality research papers indicating that homeopathic efficacy is not explained by the placebo response, the scientific community is presented with a conundrum: either homeopathy works in a way that is not yet demonstrable, or the scientific method is producing false positives at a rate that would undermine its use as a scientific tool for assessing any medical method [18].

So the question should no longer be ‘does homeopathy work?’, but rather the scientific focus should rather move towards identifying the mechanism of action of the biological effect of these medicines, and how the use of homeopathy can be incorporated within the current medical models.

In the meantime, the scientific debate on homeopathy continues to pursue the answer to this seemingly simple question.

Some sources to continue your own research:


  1. Evidence Profile for the Efficacy of Homeopathy. ECH General Assembly – XVIII Symposium of GIRI. 12 to 14th of November 2004 Scientific Report.
  2. Reilly DT, Taylor MA. Potent placebo or potency? A proposed study model with initial findings using homoeopathically prepared pollens in hay fever. Br Homoeopathic J 1985; 74: 6575.
  3. Reilly DT, Taylor MA, et al. Is homoeopathy a placebo response? Controlled trial of homoeopathic potency, with pollen in hay fever as model. Lancet 1986; ii: 881886.
  4. Reilly DT, Taylor MA, et al. Is evidence for homoeopathy reproducible? Lancet 1994; 344: 160106.
  5. Taylor MA, Reilly D, et al. Randomised controlled trial of homoeopathy versus placebo in perennial allergic rhinitis with overview of four trial series. BMJ 2000;3 21:4716.
  6. Kleijnen J, Knipschild P, et al. Clinical trials of homoeopathy. BMJ 1991;302:31623.
  7. Linde K. Are the Clinical effects of Homoeopathy Placebo Effects? A Metaanalysis of Randomised, Placebo Controlled Trials. Lancet 1997;350:83443.
  8. Boissel JP, Cucherat M, et al. Critical literature review on the effectiveness of homoeopathy: overview of data from homoeopathic medicine trials. Homoeopathic Medicine Research Group. Report to the European Commission. Brussels 1996, 195210.
  9. Cucherat M, Haugh MC, et al. Evidence of clinical efficacy of homeopathy: a metaanalysis of clinical trials. Eur J Clin Pharmacol 2000;26:2733.
  10. Jonas WB, Kaptchuk TJ,Linde K. A Critical Overview of Homeopathy. Ann Intern Med. 2003;138:393399.
  11. An Overview of Positive Homeopathy Research and Surveys. The European Network of Homoeopathic Research.  March 2007: 10-15
  12. Elia V, Niccoli M. Thermodynamics of Extremely Diluted Aqueous Solutions. Annals of the New York Academy of Sciences, 1999; 827: 241-248.
  13. Rey L. Thermoluminescence of ultra-high dilutions of lithium chloride and sodium chloride. Physica A, 2003; 323: 67-74.
  14. Belon P, Cumps J, Ennis M, Mannaioni PF, Roberfroid M, SteLaudy J, Wiegant FAC. Histamine dilutions modulate basophil activity. Inlfamm Res 2004; 53: 1818
  15.  Frenkel M, Mishra BM, Sen S, Yang P, Pawlus A, Vence L, Leblanc A, Cohen L, Banerji P, Banerji P. (2010). Cytotoxic effects of ultra-diluted remedies on breast cancer cells. Int J Oncol. 2010; 36(2): 395-403.
  16. Witt CM, Lüdtke R, Mengler N, Willich SN. How healthy are chronically ill patients after eight years of homeopathic treatment? – Results from a long term observational study. BMC Public Health, 2008; 8:413
  17. Mercer SW, Thompson T, Duncan RS, Reilly D. Evaluation of Integrated Complementary and Orthodox Care at Glasgow Homoeopathic Hospital. FACT 1998; 3(4):190.
  18. Editorial: Anon. Reilly’s challenge. Lancet 1994; 344:1585.
  19. Linde K, Scholz M, Ramirez G, et al. Impact of study quality on outcome in placebo controlled trials of homeopathy. Journal of Clinical Epidemiology, 1999; 52: 631–636.
  20. Sunila ES, Kuttan R, Preethi KC, Kuttan G. 2009. Dynamized Preparations in Cell Culture. eCAM 6(2):257-263.
  21. Biswas SJ, Khuda-Bukhsh AR. 2002. Effect of homeopathic drug, Chelidonium, in amelioration of p-DAB induced hepatocarcinogenesis in mice. BMC Compl and Alt Med 2:1-12.
  22. Biswas SJ, Khuda-Bukhsh AR. 2004. Evaluation of protective potentials of a potentised homeopathic drug Chelidonium majus, during azo dye induced hepatocarcinogenesis in mice. Indiam J Exp Bio 42:698-714.
  23. Sur RK, Samajdar K, Mitra S, et al. 1990. Hepatoprotective action of potentised Lycopodium clavatum L. Br Homeopath J 79:152-6.
  24. Chirumbolo S, Signorini A, Bianchi I, et al. 1997. Effects of Podophyllum pelatum compounds in various preparations dilutions on neutrophil function in vitro. Br Homeopathic J 86:16-26.
  25. Porozov S, Cahalon L, Weiser M, et al. 2004. Inhibition of IL-1 and TNFalpha secretion from resting and activated human immunocytes by homeopathic medication Traumeel S. Clin Dev Immunol 11:143-9.
  26. Bellavite P, Conforti A, Pontarollo F. 2006. Immunology and homeopathy 2: Cells of the immune system and inflammation. Evid Based Comp Altern Med 3:13-24.
  27. Pathak S, Multani AS, Banerji P, et al. 2003. Ruta 6 selectively induces cell death in brain cancer cells but proliferation in normal peripheral blood lymphocytes: A novel treatment for human brain cancer. Int J Cancer 23:975-82.
  28. Bastide M. Immunological examples of ultra-high dilutions research. In: Endler PC, Shhulte J (eds). Ultra High Dilution. Dordrecht: Kluwer Academic Publishers; 1994, 27-33.
  29. Bentwich Z, Weisman Z, Topper R, et al. 1993. Specific immune response to high dilutions of KLH; transfer of immunological information. In: Bornoroni C (ed). Omeomed92. Bologna: Editrice Compositiri; 1993, 9-14.
  30. Doutremepuich CH, Aguejouf O, Belon P. 1996. Effects of ultra-low dose aspirin on embolization in a model of laser induced thrombus formation. Seminars in Thrombosis and Hemostasis 22(Suppl1):67-70.
  31. Doutremepuich C, Aguejouf O, Pintigny D, Sertillanges MN, DeSeze O.1994. Thrombogenic properties of ultra low dose of acetylsalicylic acid in a vessel model of laser induced thrombus formation. Thrombosis Research 76; 2:225–9.
  32. Belougne-Malfatti E, Aguejouf O, Doutremepuich F, Belon P, Doutremepuich C. 1998. Combination of two doses of acetyl salicylic acid: experimental study of arterial thrombosis. Thrombosis Research 90:215–21.
  33. Aguejouf O, Malfatti E, Belon P, Doutremepuich C. 2000. Time related neutralization of two doses acetyl salicylic acid. Thrombosis Research 100: 317–23.
  34. Cazin JC, Cazin M, Gaborit JL, Chaoui A, Boiron J, Belon P et al. 1987. A study of the effect of decimal and centesimal dilutions of arsenic on the retention and mobilization of arsenic in the rat. Human Toxicology 1987; 6: 315–20