The End of Homeopathy
World Small Animal Veterinary Association World Congress Proceedings, 2006
Ad Rijnberk, Dr., DDr.hc
Professor Emeritus, Department of Clinical Sciences of Companion Animals, Faculty of Veterinary Medicine Utrecht University, Utrecht, The Netherlands

Samuel Hahnemann

Christian Friedrich Samuel Hahnemann was born in 1775 in Meissen, a town near Leipzig in Germany renowned for its porcelain. His father, a porcelain painter, was influenced by the Enlightenment and strived for the best education for his children. He wanted his children to become "Selbstdenker", self-thinker. Samuel Hahnemann became an inquisitive student, who provided for himself as a translator. From these translations he acquired a vast knowledge, particularly of chemistry.1

Hahnemann studied medicine at Leipzig and Vienna, taking the degree of M.D. at Erlangen in 1779. In 1782 he married the daughter of a pharmacist, Henriëtte Küchler, and in 1783, the first of his 11 children was born. From 1784-1789, the Hahnemann family lived in Dresden, where Samuel probably had a meeting with the visiting Lavoisier.2 This famous French chemist might have stimulated Hahnemann to pursue his way in chemistry. He earned a good reputation for himself by introducing a method to unmask sweetening of wine with lead and by publishing a report on arsenic poisoning.

In 1789, Hahnemann left the practice of medicine and concentrated on research and publishing. In the period between 1790 and 1805, he published a total of 5500 pages in books, articles and translations.1 From 1811 to 1821, Hahnemann lectured at the university of Leipzig on homeopathy. In 1821, the hostility of apothecaries forced him to leave Leipzig, and at the invitation of the duke of Anhalt-Köthen he went to live at Köthen. Fourteen year later he moved to Paris, where he practiced medicine with great popularity until his death in 1843.

The Similia Theory

Hahnemann developed an aversion for the practice of medicine of the late 18th century, employing bloodletting, leeching, purging and other procedures that did more harm than good. In his search for other approaches the Newtonian empiricism did not play an important role. The role model was rather the Renaissance astrologist Paracelsus, who pioneered the use of chemicals and minerals in medicine. Hahnemann always emphasised the empiric character of his method, but he had a strong passion for speculation and ontologic system building.1 While translating William Cullen's Lectures on the Materia medica into German Hahnemann was not convinced by the author's explanation of the beneficial effect of quinine in malaria patients. Cullen felt that quinine reinforced the stomach. Hahnemann took quinine himself and experienced symptoms similar to those of malaria, that is similar to the symptoms of the disordered state that quinine was used to cure. This observation led him to assert the theory that "likes are cured by likes", similia similibus curentur. Diseases are cured (or should be treated) by those drugs that produce in healthy persons symptoms similar to the diseases.3 His chief work, Organon der rationellen Heilkunst (1810; Organon of rational medicine) contains an exposition of his system, which he called Homöopathie.4 The term is derived from the Greek words homoios (similar) and pathos (suffering or disease).


After stipulation of his basic rule, Similia similibus curentur, Hahnemann increasingly tended to believe in dynamic rather than corpuscular interpretation of the action of drugs. He described the action of highly diluted solutions as "dynamic". He compared the action of drugs with warmth, magnetism and electricity. Over the years he tended to go for higher dilutions. In 1816 he recommended in Reine Arzneimittellehre dilutions up to C30 for most purposes, i.e., a dilution by a factor of 10030 = 1060

Hahnemann realized that there is little or no chance that anything of the original substance would remain after these extreme dilutions. But he believed that the vigorous shaking or pulverizing with each step of dilution promotes the release of intrinsic curing forces. In Hahnemann's view these forces, thus freed from material bonds, can affect the organism effectively.5

200 years later

Because homeopathic remedies were actually less dangerous than those of 19th-century medical orthodoxy, many medical practitioners began using them. For example at the turn of the 20th century, homeopathy had about 14,000 practitioners and schools in the United States. But as medical science and medical education advanced, homeopathy declined sharply. Schools either closed or converted to modern methods. The last pure homeopathic school in the United States closed during the 1920s.6 Nevertheless after 200 years, homeopathy is still practised by physicians and veterinarians. In recent decades it may even have gained popularity. This is largely based upon the positive effects that have been observed in clinical practice, i.e., clinical experience.

Clinical Experience

Several treatments are based upon no more than clinical experience, which is the uncontrolled conviction of the clinician that the treatment works. Some of the treatments fall into disuse after some period of time. Others persists for decades or centuries. An intriguing question is, how can ineffective treatments persist so long. At least four explanations are possible:7,8

1.  Insufficient knowledge of the natural course of the disease. In using a generally accepted treatment the clinician may loose sight of the spontaneous course of the disease. For example, in the past it was customary to treat idiopathic trigeminal neuropathy (canine dropped jaw syndrome) with corticosteroids. This was followed by a complete recovery in 2 to 3 weeks. Now it is known that the condition has an excellent prognosis without any treatment and that corticosteroids do not alter its course.

2.  Random variation. The clinician's experience is often based on a limited number of cases. As a result there is a risk of being misled by chance. If, for example, four out of five cases are cured by a treatment, it cannot be expected that 80% of future patients will be cured. Consultation of statistic tables for confidence intervals will reveal that with 95% certainty the cure rate will be somewhere between 28 and 99%.

3.  The placebo effect. Human patients seek medical advice expecting to be helped. This expectation together with the "healing environment" of the doctor's office often bring about a therapeutic effect--a positive placebo effect--no matter which treatment is given. For a wide range of afflictions, 30 to 40% of patients experience relief after taking a pharmacologically inactive tablet, a placebo.9 For veterinary medicine the situation is quite different. From the stress associated with the visit of an animal hospital,10,11,12 no beneficial effect for the animal can be expected. On the contrary (companion) animals are much better off at home.

4.  The bias of the clinician. The clinician always hopes that the treatment will be effective and thereby becomes a prejudiced or biased observer. Like everyone, clinicians seek to bolster their egos. They are like supporters of a football club who say: "we won", when the team wins and: "they lost", when it loses. Clinicians have a tendency to ascribed success to the prescribed treatment, irrespective of whether the patient's improvement could have been spontaneous.

Science and Homeopathy

When considering a possible scientific basis for homeopathy, two questions have to be answered: (1) Is there any evidence of a likely mechanism?, and (2) Have clinical trials demonstrated effects better than a placebo?

1.  Mechanism. The dilution far beyond Avogadro's number (6 x 1023) makes it very unlikely that one molecule of the original substance would be present in a C30 solution. Thus a pharmacological action based upon molecular interaction cannot be expected. What remains is the belief of homeopaths that these dilutions retain some "essential property" (curing force) of the substance once present. The most sensational attempt to prove the latter has been the study of Benveniste and co-workers on the effects of extremely diluted antibody solutions. They found that aqueous solutions of anti-immunoglobulin E (anti-IgE) still retain an ability to cause degranulation of human basophilic granulocytes, even when diluted to the point where there are no anti-IgE molecules left in the solution. The report was accepted for publication in Nature,13 under the condition that identical results had to be obtained when the experiment was repeated in Benveniste's laboratory under the observation of a delegation composed by the editor-in-chief. When the experiment was repeated, the activation of basophils in tubes treated with the "homeopathic diluted antigen" did not differ from that of the control tubes, which were only treated with the solvent. Also in other laboratories Benveniste's claim of transmission of biological information to the molecular organization of water could not be confirmed.14

2.  Trials. In human medicine many randomised trials have been performed, comparing homeopathic treatment with a placebo. Several of the trials had major flaws in their design. In recent years the reports have been summarized in meta-analyses. In these critical reviews of the publications on the effectiveness of homeopathy there is special attention for the methodological aspects. The early meta-analyses were somewhat inconclusive. The authors felt that it could not be excluded that individualized homeopathy has an effect over placebo.15,16 Although they added that the results of their analyses might have been coloured positively by publication bias, that is, a report with a positive result is more likely to be published than a report with negative result. Evidence of bias made some authors confess that this weakened the original meta-analysis, i.e., caused overestimation of the effects of homeopathic treatments.17

In 2002, Edzard Ernst of the Department of Complementary Medicine of the University of Exeter in England published an analysis of systematic reviews/meta-analyses.18 He could not provide strong evidence in favour of homeopathy. In particular, there was no condition responding convincingly better to homeopathic treatment than to placebo or other control interventions. Similarly, there was no homeopathic remedy that was demonstrated to yield clinical effects of that are convincingly different from placebo. Ernst concluded that the best clinical evidence for homeopathy available does not warrant positive recommendations for its use in clinical practice. In 2005 investigators from Switzerland and the United Kingdom reported a comparative study of 110 homeopathic trials and 110 matched conventional-medicine trials. Biases were present in placebo-controlled trials of both homeopathy and conventional medicine. When account was taken for these biases in the analysis, there was a weak evidence for a specific effect of homeopathic remedies, but strong evidence for specific effects of conventional interventions. The authors conclude that this finding is compatible with the notion that the clinical effects of homeopathy are placebo effects.19

The few well-designed trials in veterinary medicine also failed to demonstrate efficacy of homeopathy.20,21

The End

Homeopathy has not withstood scientific testing.22 It is felt that for too long a politically correct laissez-faire attitude has existed towards homeopathy, but there is some light.23 For example in the United Kingdom a Parliamentary Committee has issued a report about complementary and alternative medicine, stating that "any therapy that makes specific claims for being able to treat specific conditions should have evidence of being able to do this above and beyond the placebo effect".23 The Swiss Government has withdrawn insurance coverage for homeopathy and four other complementary treatments.

There is no justification for further investment in research to perpetuate the homeopathy versus allopathy debate. In an editorial comment in The Lancet it was put as follows: "Now doctors need to be bold and honest with their patients about homeopathy's lack of benefit, ...".23

In November 2005 the Federation of Veterinarians in Europe (FVE) has issued a strategy document, including the statement that the veterinary profession is rooted in science and evidence-based veterinary medicine.24 In the explanatory discussion of this strategy document it was explicitly said that the FVE rejects non-evidence based medicines such as homeopathy.25

Earlier in 2005 the European Board of Veterinary Specialisation (EBVS) made a clear statement with regard to alternative modes of treatment: The EBVS only recognises scientific, evidence-based veterinary medicine complying with animal welfare legislation. Specialists or colleges practising or supporting implausible treatments with no proof of effectiveness run the risk of withdrawal of their specialist status. No credit points can be granted for education or training in these so-called supplementary, complementary and alternative modes of treatment.26


1.  De Goeij CM. Samuel Hahnemann: een verontwaardigd systeembouwer. Ned Tijdschr Geneeskd 1994; 138:310-314.

2.  Haehl R. Samuel Hahnemann, sein Leben und Schaffen. Leipzig, W. Schwabe, 1922.

3.  Hahnemann S. Versuch über ein neues Prinzip zur Auffindung der Heilkräfte der Arzneisubstanzen, nebst einigen Blicken auf die bisherigen. Journal der practischen Arzneykunde und Wundarzneykunst. Jena, 1796; 2.3:391-439 & 2.4:465-561.

4.  Hahnemann S. Organon der Geneeskunst. Translation of the 6th edition of 1921 in Dutch. Alkmaar: VSB Geneesmiddelen, 1983: § 279.

5.  In 1825 Hahnemann wrote: "Dürch Reibungen (Schütteln) kommt die innere Arneikraft wundersam zum Leben und befreit sich gleichsam von den Banden der Materie, um desto eindringlicher und freier auf den Menschlichen Organismus würken zu können. Hahnemann S. Belehrung für den Wahrheitssucher. Allgemeine Anzeiger der Deutschen 1825; 194: 2387-2392. Cited in ref. 1.

6.  Barret S. Homeopathy: The Ultimate Fake.

7.  Wulff HR. Rational diagnosis and treatment. An introduction to clinical decision-making. 2nd edn. Blackwell Scientific Publications. Oxford, 1981.

8.  Rijnberk A. Modes of treatment.Austral Vet J 1997; 75:260-261.

9.  Brown WA. The placebo effect. Scient Amer 1998(Jan):90-95.

10. Van Vonderen IK, Kooistra HS, Rijnberk A. Influence of veterinary care on the urinary corticoid;creatinine ratio in dogs. J Vet Intern Med 1998; 12:431-435.

11. Zimmer C Reusch CE. Untersuchungen zum Kortisol-Kreatinin-Verhältnis im Urin (UCC) bei gesunden Katzen. Schweiz Arch Tierheilk 2003; 145:323-328.

12. Cauvin AL, Witt AL, Groves E, Neiger R, Martinez T, Church DB. The urinary corticoid-creatinine ratio (UCCR) in healthy cats undergoing hospitalisation. J Feline Med Surg 2003: 5:329-333.

13. Davenas E, Beauvais F, Amara J, Oberbaum M, Robinzon B, Miadonna A, Tedeschi A, Pomeranz B, Fortner P, Belon P, Sainte-Laudy J, Poitevin B, Benveniste J. Human basophil degranulation triggered by very dilute antiserum against IgE. Nature 1988; 333:816-818

14. Metzger H, Dreskin SC. Only the smile is left. Nature 1988; 334:375.

15. Kleijnen J, Knipschild P, ter Riet G. Clinical trials of homeopathy. Brit Med J 1991; 302:316-323.

16. Linde K, Clausius N, Ramirez G, Melchart D, Eitel F, Hedges LV, Jonas WB. Are the clinical effects of homeopathy placebo effects? A meta-analysis of placebo-controlled clinical trials. Lancet 1997; 350:834-843.

17. Linde K, Scholz M, Ramirez G, Clausius N, Melchart D,Jonas WB. Impact of study quality on outcome in placebo-controlled trials in homeopathy. J Clin Epidemiol 1999; 52:631-636.

18. Ernst E. A systematic review of systematic reviews of homeopathy. Brit J Clin Pharmacol 2002; 54:577-582.

19. Shang A, Kuwiler-Müntener K, Nartey L, Jüni P, Dörig S, Sterne JAC, Pewsner D. Egger M. Are the clinical effects of homoeopathy placebo effects? Comparative study of placebo-controlled trials of homoeopathy and allopathy. Lancet 2005; 366:726-732.

20. De Verdier K, Ohagen P, Alenius S. No effect of a homeopathic preparation on neonatal calf diarrhoea in a randomised double-blind, placebo-controlled clinical trial. Acta Vet Scand 2003; 44:97-101.

21. Holmes MA, Cockcroft PD, Booth CE, Heath MF. Controlled clinical trial of the effect of a homoeopathic nosode on the somatic cell counts in the milk of clinically normal dairy cows. Vet Rec 2005; 156:565-567.

22. Van Sluijs FJ. Kan de homeopathie de toets der wetenschap doorstaan? Tijdschr Diergeneeskd 2004; 127:295-298. English translation in Veterinary Science Tomorrow: Can homeopathy withstand scientific testing?

23. Editorial. The end of homeopathy. Lancet 2005; 366:690.

24. FVE's Strategy 2006-2010. Improving the health and welfare of animals and people. Brussels, FVE, 2005.

25. Minutes of the General Assembly Meeting of the FVE, Brussels, November 2005.

26. - policies and procedures, page 9.

Speaker Information
(click the speaker's name to view other papers and abstracts submitted by this speaker)

Ad Rijnberk, Prof.em.,Dr.,DDr. hc
Department of Clinical Sciences of Companion Animals
Utrecht University
Utrecht, The Netherlands

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