How do we know homeopathic medicines are not “just sugar pills”?

Laboratory experiments have demonstrated that homeopathic medicines are not just sugar pills.

Critics of homeopathy point to the fact that homeopathic medicines are so highly diluted that there is ‘nothing in them’.

This comes from the fact that the liquids used to make some homeopathic medicines are diluted beyond the threshold known as Avogadros number (dilution 10-23). This means that the liquid is so highly diluted that you would not expect any molecules of the original substance to remain.

It is these ‘ultra-high dilutions’ (homeopathic medicines above 12c or 24x potency) which attract controversy, because they clearly cannot work in the same way as conventional medical drugs i.e. through molecules interacting directly with the body’s biochemistry.

Researchers around the world are investigating the mechanism of action of these medicines, which is likely to be based in physics rather than chemistry. Although there are various theories being explored, as yet, we do not understand how homeopathic medicines work.

What we do know is that many laboratory studies have shown ultra-high dilution homeopathic medicines having biological effects you would not see if they were ‘just water’ or ‘just sugar pills’, for example:

Adding homeopathic histamine to basophils (white blood cells) can trigger them to release histamine


 As the people who originally designed this experiment explain, “When human polymorphonuclear basophils, a type of white blood cell with antibodies of the immunoglobulin E (IgE) type on its surface, are exposed to anti-IgE antibodies, they release histamine from their intracellular granules and change their staining properties. The latter can be demonstrated at dilutions of anti-IgE that range from 10-2 to 10-120; over that range, there are successive peaks of degranulation from 40 to 60% of the basophils, despite the calculated absence of any anti-IgE molecules at the highest dilutions.”

28 scientific papers have been published on this topic, 23 of which reported positive results. 11 publications were judged to be of high quality, of which 8 reported positive results.1

The earliest study reported inhibition of degranulation with ultra-molecular dilutions of anti-IgE,2 but these initial experiments proved to be unreproducible.3,4

However, subsequent studies using a modified method and using ultra-molecular dilutions of histamine, have shown positive results. These findings have been reproduced in several independent laboratories,5,6 as well as in a multi-centre series of experiments.7

Homeopathic thyroxine, at the ultra-high dilution of 30x, slows down the rate at which tadpoles turn into frogs 8


 In amphibians, the hormone thyroxine stimulates metamorphosis. Over almost 20 years, various teams have tested homeopathic dilutions of thyroxine on frogs by adding it to the bathing water tadpoles are kept in. An independent meta-analysis of these trials identified 22 experiments – 15 carried out by the original team in Austria and 5 by independent researchers.8 All 22 experiments found the same trend – that thyroxine 30x (diluted beyond Avogadro’s limit using the homeopathic manufacturing process) inhibits metamorphosis, though the exact results varied. This effect has now been observed by 7 researchers from Austria, Germany, Switzerland + the Netherlands.

Are these results just artifacts from ‘bad science’?

This argument does not hold up to any scrutiny because even experiments with a high methodological standard can demonstrate ultra high dilutions (a.k.a. ‘high potencies’) having effects.1

Why are these results not accepted by some scientists?

So far, no positive result has been stable enough to be reproduced by all researchers every time. Close to 75% of in vitro experiments on ultra-high dilutions show the substance having an effect, and nearly 75% of replications have been positive.1

As scientists gain more experience experimenting on ultra-high dilutions, they are gradually understanding what factors are influencing the results and consequently, reproducibility is improving 9. The basophil and frog experiments described above have proved the most repeatable so far and progress is also being made in finding the most repeatable plant-based experiments.

However, until an experiment is achieved in which every team gets the same effect every time, this field will remain controversial. This is the ongoing challenge for basic science researchers in homeopathy.

The key appears to be in exactly how homeopathic medicines are made

Homeopathic medicines are made from plant, chemical, mineral or animal sources. The original material is diluted, then agitated vigorously (succussed). The number of times this is repeated determines the strength or ‘potency’ of the remedy e.g. a ‘6c’ remedy will have been diluted 1 part in 100 then succussed, six times over.

If you only dilute the substance over and over, of course you are eventually left with an inactive sample which is ‘just water’; it is the added succussion between each step of dilution which appears to imprint information from the original substance, into the water/alcohol it is diluted in.

This idea is supported by experiments which show that unsuccussed dilutions are inactive, but succussed dilutions can cause biological effects, suggesting that this aspect of the manufacturing process is essential in creating homeopathic medicines10.

Exactly what physico-chemical changes succussion causes, and how this enables water to capture information about the substances diluted in it, are the big questions researchers are trying to answer.


  1. Witt CM, Bluth M, Albrecht H, Weisshuhn TE, Baumgartner S, Willich SN. The in vitro evidence for an effect of high homeopathic potencies–a systematic review of the literature. Complement Ther Med., 2007; 15(2): 128-38 | PubMed
  2. Davenas E, Beauvais F, Amara J, et al. Human basophil de-granulation triggered by very dilute antiserum against IgE. Nature, 1988; 333: 816–818 | PubMed
  3. Ovelgönne JH, Bol AW, Hop WC, van Wijk R. Mechanical agitation of very dilute antiserum against IgE has no effect on basophil staining properties. Experientia, 1992; 48: 504–508 | PubMed
  4. Hirst SJ, Hayes NA, Burridge J, et al. Human basophil degranulation is not triggered by very dilute antiserum against human IgE. Nature, 1993;366: 525–527 | PubMed
  5. Belon P, Cumps J, Ennis M, et al. Inhibition of human basophil degranulation by successive histamine dilutions: results of a European multi-centre trial. Inflammation Research, 1999; 48 (Suppl 1): S17–18 | PubMed
  6. Lorenz I, Schneider EM, Stolz P, et al. Sensitive flow cytometric method to test basophil activation influenced by homeopathic histamine dilution. Forschende Komplementärmedizin, 2003; 10: 316–324 | PubMed
  7. Belon P, Cumps J, Ennis M, et al. Histamine dilutions modulate basophil activation. Inflammation Research, 2004; 53: 181–188 | PubMed
  8. Harrer B. Replication of an experiment on extremely diluted thyroxine and
highland amphibians. Homeopathy, 2013;102(1):25-303 | PubMed
  9. Endler P, Thieves K, Reich C, Matthiessen P, Bonamin L, Scherr C, Baumgartner S. Repetitions of fundamental research models for homeopathically prepared dilutions beyond 10(-23): a bibliometric study. Homeopathy, 2010; 99(1): 25-36 | PubMed | HRI Synopsis
  10. Betti L, et al. Effectiveness of ultra high diluted arsenic is a function of succussion number as evidenced by wheat germination test and droplet evaporation method. Int J High Dilution Res, 2013; 12 (44): 127–128 | Full text

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Testing homeopathy on plants

Dr Stephan Baumgartner
University of Berne

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