Clinical trials overview

By the end of 2014, 189 randomised controlled trials of homeopathy on 100 different medical conditions had been published in peer-reviewed journals:1
Of these, 104 papers were placebo-controlled and were eligible for detailed review:

  • 41% were positive (43 trials) – finding that homeopathy was effective
  • 5% were negative (5 trials) – finding that homeopathy was ineffective
  • 54% were inconclusive (56 trials)

Meta-analyses of homeopathy trials

There have been 6 meta-analyses of homeopathy:

  • five were positive – suggesting that there was some evidence of an effect of homeopathy beyond placebo, but more high quality research would be needed to reach definitive conclusions2,3,4,5,7
  • one was negative – concluding that homeopathy had no effect beyond placebo:6 More about this study here.

Original conclusions from the 6 meta-analysesLess

  • Kleijnen et al. 1991: ‘At the moment the evidence of clinical trials is positive but not sufficient to draw definitive conclusions because most trials are of low methodological quality and because of the unknown role of publication bias. This indicates that there is a legitimate case for further evaluation of homoeopathy, but only by means of well performed trials.’2
  • Linde et al. 1997: ‘The results of our meta-analysis are not compatible with the hypothesis that the clinical effects of homeopathy are completely due to placebo. However, we found insufficient evidence from these studies that homeopathy is clearly efficacious for any single clinical condition. Further research on homeopathy is warranted provided it is rigorous and systematic.’ 3
  • Linde et al. 1999: ‘We conclude that in the study set investigated, there was clear evidence that studies with better methodological quality tended to yield less positive results.’4
  • Cucherat et al. 2000: ‘There is some evidence that homeopathic treatments are more effective than placebo; however, the strength of this evidence is low because of the low methodological quality of the trials. Studies of high methodological quality were more likely to be negative than the lower quality studies. Further high quality studies are needed to confirm these results.’5
  • Shang et al. 2005: ‘Biases are present in placebo-controlled trials of both homoeopathy and conventional medicine. When account was taken for these biases in the analysis, there was weak evidence for a specific effect of homoeopathic remedies, but strong evidence for specific effects of conventional interventions. This finding is compatible with the notion that the clinical effects of homoeopathy are placebo effects.’6
  • Mathie et al. 2014: ‘Medicines prescribed in individualised homeopathy may have small, specific treatment effects. Findings are consistent with sub-group data available in a previous ‘global’ systematic review. The low or unclear overall quality of the evidence prompts caution in interpreting the findings. New high-quality RCT research is necessary to enable more decisive interpretation.’7

Developing the evidence base – progress from 2005 to 2014

The sixth and most recent meta-analysis by Mathie et al., published in 2014, found that homeopathic medicines, when prescribed during individualised treatment, are 1.5- to 2.0-times more likely to have a beneficial effect than placebo.7 

Although the previous meta-analysis by Shang et al. continues to be referred to frequently, the 2014 study by Mathie et al. includes 151 placebo-controlled randomised trials41 more than Shang’s team identified in 2005, but which would have met their inclusion criteria if available at the time.

This demonstrates the extent to which the 10 year-old Shang et al. paper, which now covers only 73% of the eligible trials, has been superseded by the paper by Mathie et al..

Read HRI’s brief summary of Mathie et al.’s study or listen to Robert Mathie presenting his findings at the HRI Rome 2015 conference:



  1. Faculty of Homeopathy | Link
  2. Kleijnen, J., Knipschild, P. & ter Riet, G. Clinical trials of homeopathy. BMJ, 1991; 302: 960 | PubMed
  3. Linde, K. et al. Are the clinical effects of homeopathy placebo effects? A meta-analysis of placebo-controlled trials. Lancet, 1997; 350:834–843 | PubMed
  4. Linde, K. et al. Impact of study quality on outcome in placebo-controlled trials of homeopathy. J. Clin. Epidemiol., 1999; 52: 631–636 | PubMed
  5. Cucherat, M., Haugh, M. C., Gooch, M. & Boissel, J. P. Evidence of clinical efficacy of homeopathy. A meta-analysis of clinical trials. HMRAG. Homeopathic Medicines Research Advisory Group. Eur. J. Clin. Pharmacol., 2000; 56: 27–33 | PubMed
  6. Shang A, Huwiler-Muntener K, Nartey L, et al. Are the clinical effects of homeopathy placebo effects? Comparative study of placebo-controlled trials of homeopathy and allopathy. Lancet, 2005; 366: 726–732 | PubMed
  7. Mathie RT et al. Randomised placebo-controlled trials of individualised homeopathic treatment: systematic review and meta-analysis. Systematic Reviews, 2014; 3: 142
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2-There isn’t a single RCT_shutterstock_100245305 adjusted

2-There isn’t a single RCT_shutterstock_100245305 adjusted