Majority of Research on Homeopathic Remedies Unpublished or Unregistered: Study

Heidi Splete

March 17, 2022

More than half of research on homeopathic remedies is unpublished or unregistered, according to a new analysis.

Homeopathy is a form of alternative medicine based on the concept that increasing dilution of a substance leads to a stronger treatment effect.

The authors of the new paper, published in BMJ Evidence-Based Medicine, also found that a quarter of the 90 randomized published trials on homeopathic remedies they analyzed changed their results before publication.

The benefits of homeopathy touted in studies may be greatly exaggerated, suggest the authors, Gerald Gartlehner, MD, of Danube University, Krems, Austria, and colleagues.

The results raise awareness that published homeopathy trials represent a limited proportion of research, skewed toward favorable results, they wrote.

"This likely affects the validity of the body of evidence of homeopathic literature and may substantially overestimate the true treatment effect of homeopathic remedies," they concluded.

Homeopathy as practiced today was developed approximately 200 years ago in Germany, and despite ongoing debate about its effectiveness, it remains a popular alternative to conventional medicine in many developed countries, the authors noted.

According to the National Institutes of Health, homeopathy is based on the idea of "like cures like," meaning that a disease can be cured with a substance that produces similar symptoms in healthy people, and the "law of minimum dose," meaning that a lower dose of medication will be more effective. "Many homeopathic products are so diluted that no molecules of the original substance remain," according to the NIH.

Homeopathy is not subject to most regulatory requirements, so assessment of effectiveness of homeopathic remedies is limited to published data, the researchers said. "When no information is publicly available about the majority of homeopathic trials, sound conclusions about the efficacy and the risks of using homeopathic medicinal products for treating health conditions are impossible," they wrote.

Study Methods and Findings

The researchers examined 17 trial registries for studies involving homeopathic remedies conducted since 2002.

The registries included, the EU Clinical Trials Register, and the International Clinical Trials Registry Platform up to April 2019 to identify registered homeopathy trials.

To determine whether registered trials were published and to identify trials that were published but unregistered, the researchers examined PubMed, the Allied and Complementary Medicine Database, Embase, and Google Scholar up to April 2021.

They found that approximately 38% of registered trials of homeopathy were never published, and 53% of the published randomized, controlled trials (RCTs) were not registered. Notably, 25% of the trials that were registered and published showed primary outcomes that were changed compared with the registry.

The number of registered homeopathy trials increased significantly over the past 5 years, but approximately one-third (30%) of trials published during the last 5 years were not registered, they said. In a meta-analysis, unregistered RCTs showed significantly greater treatment effects than registered RCTs, with standardized mean differences of –0.53 and –0.14, respectively.

The study findings were limited by several factors including the potential for missed records of studies not covered by the registries searched. Other limitations include the analysis of pooled data from homeopathic treatments that may not generalize to personalized homeopathy, and the exclusion of trials labeled as terminated or suspended.

Proceed With Caution Before Recommending Use of Homeopathic Remedies, Says Expert

Linda Girgis, MD, noted that prior to reading this report she had known that most homeopathic remedies didn't have any evidence of being effective, and that, therefore, the results validated her understanding of the findings of studies of homeopathy.

The study is especially important at this time in the wake of the COVID-19 pandemic, Girgis, a family physician in private practice in South River, N.J., said in an interview.

"Many people are promoting treatments that don't have any evidence that they are effective, and more people are turning to homeopathic treatments not knowing the risks and assuming they are safe," she continued. "Many people are taking advantage of this and trying to cash in on this with ill-proven remedies."

Homeopathic remedies become especially harmful when patients think they can use them instead of traditional medicine, she added.

Noting that some homeopathic remedies have been studied and show some evidence that they work, Girgis said there may be a role for certain ones in primary care.

"An example would be black cohosh or primrose oil for perimenopausal hot flashes. This could be a good alternative when you want to avoid hormonal supplements," she said.

At the same time, Girgis advised clinicians to be cautious about suggesting homeopathic remedies to patients.

"Homeopathy seems to be a good money maker if you sell these products. However, you are not protected from liability and can be found more liable for prescribing off-label treatments or those not [Food and Drug Administration] approved," Girgis said. Her general message to clinicians: Stick with evidence-based medicine.

Her message to patients who might want to pursue homeopathic remedies is that just because something is "homeopathic" or natural doesn't mean that it is safe.

"There are some [homeopathic] products that have caused liver damage or other problems," she explained. "Also, these remedies can interact with other medications."

The study received no outside funding. The researchers and Girgis had no financial conflicts to disclose.

This article originally appeared on, part of the Medscape Professional Network.


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