Research to date

There have been a number of studies designed to try and establish whether homeopathy is effective.

Most have been carried out by homeopathic practitioners and published in homeopathic journals.

A comprehensive list of studies can be found here. We shall focus on three that are commonly used by homeopathic practitioners as evidence that homeopathy is effective.

Camerlink, I., Ellinger, L., Bakker, E.J., Lantinga, E.A., (2010) Homeopathy as replacement to antibiotics in the case of Escherichia coli diarrhoea in neonatal piglets. Homeopathy Vol. 99 no. 1, pp. 57-62

They say: "Piglets of the homeopathic treated group had significantly less E. coli diarrhoea than piglets in the placebo group (P<.0001). Especially piglets from first parity sows gave a good response to treatment with Coli 30K. The diarrhoea seemed to be less severe in the homeopathically treated litters, there was less transmission and duration appeared shorter."

We say: For its diagnosis of E. coli infection, the study relied on the "day of appearance and colour" of diarrhoea observed in the animals, which is an unreliable way of diagnosing an E. coli infection. A limited number of cultures were carried out, evidently at the start of the study, which found no evidence of E. coli in the first place. Furthermore, the study was described only as 'observer-blind'. In other words, leaving it wide open to confirmation bias from other parties involved with the study (the stockmen, whoever presented the pigs for observation or administered the remedy, or the statisticians). More detailed critiques can be read here, and here.

Bracho, G., Varela, E., Fernandez, R., Ordaz, B., Marzoa, N., Menendez, J., Garcia, L., Gilling, E., Leyva, R., Rufin, R., de la Torre, R., Solis, R.L., Batista, N., Borrero R., Campa, C., (2010) Large-scale application of highly-diluted bacteria for Leptospirosis epidemic control Homeopathy Vol. 99 pp. 156-166

They say: "The homeoprophylactic approach was associated with a large reduction of disease incidence and control of the epidemic. The results suggest the use of HP [homeopathy] as a feasible tool for epidemic control, further research is warranted."

We say: This study, which claimed the entire population of Cuba as the study group, had no proper control groups and no randomisation. The study was also deeply flawed by considerable amount of publicity given to the study at the time it was carried out (not to mention a large number of medical professionals deployed to administer the remedy), and the fact that conventional medicines and other control strategies were also used in the area where the remedy was used. Whilst there was a short term reduction in leptispirosis in the treatment area, there are many more plausible explanations which the study failed to exclude, such as the naturally cyclical nature of the disease and the impact of changed behaviour (improved control measures) in the treatment area as a result of the intervention. The fact that post treatment levels of disease returned to normal levels once flooding subsided tends to support this hypothesis. More detailed critiques available here and here.

Linde, K., et al (1997) Are the clinical effects of homoeopathy placebo effects? A meta-analysis of placebo-controlled trials Lancet Vol. 350 no. 9081 pp. 834-843

They say: "The results of our meta-analysis are not compatible with the hypothesis that the clinical effects of homoeopathy are completely due to placebo. However, we found insufficient evidence from these studies that homoeopathy is clearly efficacious for any single clinical condition. Further research on homoeopathy is warranted provided it is rigorous and systematic."

We say: This research was subsequently reanalysed 6 times, not least by Linde himself, and on each occasion produced a negative result. Linde also published another paper in 1999 (Linde, K. and Melchart, D., (1998) Randomized controlled trials of individualized homeopathy: a state-of-the-art review. J Altern Complement Med. Vol. 4 no.4 pp371-88.) which said: "when the analysis was restricted to the methodologically best trials no significant effect was seen", and concluded that: "The results of the available randomized trials suggest that individualized homeopathy has an effect over placebo. The evidence, however, is not convincing because of methodological shortcomings and inconsistencies."

And the evidence that homeopathy is ineffective?

A number of meta analyses have concluded that homeopathy is ineffective, most famously Shang et al. However, perhaps the most compelling evidence against homeopathy are two independent Government reports, both tasked with assessing the evidence for homeopathy and its role in human medicine.

House of Commons Science and Technology Committee. Evidence Check 2. Homeopathy. 2010

This in depth review by the Government considered all the available scientific evidence presented both by proponents and critics of homeopathy. It looked at the plausibility, evidence-base and ethics surrounding homeopathy. Amongst the conclusions were:

We conclude that the principle of like-cures-like is theoretically weak. It fails to provide a credible physiological mode of action for homeopathic products. We note that this is the settled view of medical science.

We consider the notion that ultra-dilutions can maintain an imprint of substances previously dissolved in them to be scientifically implausible.

In our view, the systematic reviews and meta-analyses conclusively demonstrate that homeopathic products perform no better than placebos. The Government shares our interpretation of the evidence.

Homeopathy should not be funded on the NHS and the MHRA should stop licensing homeopathic products.

Australian Government National Health and Medical Research Council. Evidence on the effectiveness of homeopathy for treating health conditions. March 2015.

This report included a meta analysis of no less than 225 papers selected by an independent research company to meet minimum scientific criteria. It reached some pretty strong conclusions:

Based on the assessment of the evidence of effectiveness of homeopathy, NHMRC concludes that there are no health conditions for which there is reliable evidence that homeopathy is effective. Homeopathy should not be used to treat health conditions that are chronic, serious, or could become serious.

People who choose homeopathy may put their health at risk if they reject or delay treatments for which there is good evidence for safety and effectiveness.


The placebo effect, where a patient experiences a beneficial effect of treatment because of their belief in that treatment (and not the treatment itself), is often used as an argument for the use of homeopathic remedies.

In veterinary medicine, of course, animals are not able to experience a beneficial effect of treatment because of a belief in treatment. Instead, the placebo effect can only affect the care-giver, be they the veterinary surgeon or the owner.

On the one hand, there is a hypothesis that the use of a placebo in veterinary medicine might change the behaviour of the owner: their belief in the efficacy of the placebo reducing their stress and worry over the sick pet, with a consequent beneficial effect on the animal.

However, more plausible (and indeed demonstrated), is the phenomenon where the caregiver believes they have seen an effect attributable to the treatment, when in reality there has been none. So whilst the owner continues to report an improvement, the animal continues to suffer.