Homeopathy

Hahnemann's early writings, 1790 to 1810

Samuel Hahnemann (1755 to 1843) is the physician credited with founding homeopathy. A 2011 essay by the medical historian Josef Schmidt traces its development over more than 50 years, from 1790 to 1842. Schmidt dates the first step to 1790, when Hahnemann published a self-experiment with cinchona bark and remarked that substances which provoke a kind of fever extinguish types of intermittent fever. In 1796 an essay in Hufeland's journal first set out two principles: testing medicines on healthy volunteers and treating like with like.

Schmidt reports that Hahnemann coined the adjective homeopathic in 1807, and that the 1810 first edition of his Organon, published in Dresden, first used the noun homeopathy and gave the full Latin maxim similia similibus curentur. Schmidt adds that the 1810 book neither founded homeopathy in the strict sense nor ended its development.

Editions of the Organon

The first edition was titled Organon of Rational Medicine. Four revised editions appeared in Hahnemann's lifetime under the title Organon of the Art of Healing (1819, 1824, 1829 and 1833), and the fifth, especially in its English translation, became the most widely read. Hahnemann finished a sixth edition as a manuscript in 1842. It was published only after his death, in 1921 from a copy and in 1992 as a critical edition of the original manuscript.

Schmidt describes a change of emphasis in 1819 from rational therapeutics toward an art of healing, and a break in 1828 when Hahnemann's book on chronic diseases attributed them to earlier infection with chronic miasms, which he called psora, syphilis and sycosis. This theory was built into the 1829 edition. Hahnemann's concepts therefore shifted over time, and no single edition describes all later practice.

Later changes to dosing

According to Schmidt, later editions recommended a thirtieth centesimal potency (C30) as a standard dose, often given by smelling, and the sixth edition described the preparation of Q potencies. A review of Hahnemann's casebooks found 1,836 prescriptions of fifty-millesimal potencies between 1837 and 1843, and the reviewers concluded that he probably decided to write the sixth edition in 1840. The sources reviewed here do not cover the later spread of homeopathy to other countries.

Names and related labels

Homeopathy is also spelled homoeopathy. Schmidt notes that Hahnemann used the label allopathy for non-homeopathic medicine, and distinguished homeopathy from isopathy, the treatment of like with the same substance. Allopathy is therefore a term from within the homeopathic tradition, and this page uses conventional medicine instead. Trials of isopathy have been included in some reviews of homeopathy, for example in allergic rhinitis.

Potentization, dilution and succussion

The Australian National Health and Medical Research Council (NHMRC) describes preparation as repeatedly diluting a substance in water or alcohol and forcefully hitting the container against a hand or surface, a process called potentiation or dynamisation. It lists two premises: that a substance causing symptoms in a healthy person can in very small doses treat those symptoms in someone ill, and that highly diluted preparations retain a memory of the original substance.

The National Center for Complementary and Integrative Health (NCCIH) adds a law of minimum dose, under which lower doses are said to work better, and says many products are so diluted that no molecules of the original substance remain. Potency labels such as C30 refer to the centesimal scale, and Q potencies to the fifty-millesimal scale. Whether the memory premise has any physical basis was outside the scope of the NHMRC review, which excluded laboratory studies.

Individualized and clinical homeopathy

NHMRC distinguishes individualized homeopathy, in which a homeopath matches all of a person's symptoms to a single medicine, from clinical homeopathy, in which one or more medicines are chosen for a particular health condition. Trial reviewers use a parallel split between individualized and non-individualized treatment, and it affects how studies are grouped and interpreted.

Remedies and forms

NCCIH reports that remedies start from plants, minerals or animal material, for example red onion, arnica, white arsenic or crushed bees, and are supplied as sugar pellets placed under the tongue, ointments or drops. NHMRC also lists tablets, liquids, sprays and creams. The page does not describe a standard consultation format, and none of the sources reviewed for this article gives a typical visit length or schedule.

How a remedy is chosen

NCCIH says treatment is individualized, so two people with the same condition may be given different remedies. In the historical account, Hahnemann's 1796 essay proposed finding a medicine's effects by testing it on healthy volunteers, and practitioners describe matching the person's whole symptom picture to the effects recorded for a medicine. NHMRC notes that clinical homeopathy, which targets a condition, is also common, and that most studies in its review used that approach.

Training and professional registers

In the United Kingdom, the Society of Homeopaths states that its recognized courses are reviewed against UK Higher Education Level 6 standards and national occupational standards, and that graduates may apply for the RSHom designation and a place on its public register, subject to membership requirements. This is the society's own description and has not been independently audited. Training and certification in other countries, and regulation of products or practitioners by public authorities, are not covered here.

Conditions for which homeopathy is offered or studied

Homeopathy has been tested across a wide range of conditions. An individualized-treatment review covered 24 conditions, and a review of standardized treatment covered 48. In the NHMRC assessment, homeopathy interest groups and members of the public submitted studies on conditions that included rheumatoid arthritis, influenza-like illness, hot flushes, rhinosinusitis, ankle sprain, insomnia, stress, warts, knee osteoarthritis, chronic low back pain, upper respiratory tract infection and otitis media. These lists show where studies exist and do not endorse any use.

What the sources do not assess

The NHMRC review did not consider laboratory or animal studies, prevention of illness, homeopathic vaccines, or whether homeopathy supports general health and wellbeing. It also focused on effectiveness and not on safety. Claims in those areas are therefore not assessed in this article, and no source reviewed here supports them.

Early syntheses: Ernst 2002 and Shang 2005

A 2002 review of systematic reviews found 17 articles, six of which re-analyzed a single landmark meta-analysis. It concluded that the independent reviews did not give strong evidence for homeopathy and that no condition responded convincingly better than to placebo or other controls. In 2005 Shang and colleagues compared 110 placebo-controlled homeopathy trials with 110 matched conventional-medicine trials, finding smaller and lower-quality trials gave more favorable results in both groups. In the largest higher-quality trials the odds ratio was 0.88 (95% confidence interval 0.65 to 1.19) for homeopathy (8 trials) and 0.58 (0.39 to 0.85) for conventional medicine (6 trials). The authors called the evidence for a specific effect of homeopathic remedies weak.

Reviews by Mathie and colleagues

A 2014 review of 32 randomized placebo-controlled trials of individualized homeopathy (24 conditions) rated 20 high risk of bias. Pooling 22 trials gave an odds ratio of 1.53 (1.22 to 1.91) favoring homeopathy, and 1.98 (1.16 to 3.38) for the three trials judged reliable. The authors concluded that individualized medicines may have small specific effects, while advising caution because of low or unclear quality.

The 2017 review of non-individualized treatment (75 trials, 48 conditions) found a pooled standardized mean difference of -0.33 (-0.44 to -0.21), shrinking to -0.16 (-0.31 to -0.02) after adjustment for publication bias. The three reliable trials gave a non-significant -0.18 (-0.46 to 0.09), and no single condition had reliable evidence. The authors judged the body of evidence low in quality. Their affiliations include the British Homeopathic Association and the Homeopathy Research Institute.

The NHMRC evidence review, 2015

The NHMRC overview identified 57 systematic reviews containing 176 controlled studies in humans, and assessed 42 additional published studies submitted by homeopathy groups and the public. The additional studies did not change the findings. Homeopathy was compared with placebo for 55 conditions: 13 showed no benefit over placebo, 14 had favorable studies judged unreliable, and 29 had one unreliable study. NHMRC concluded that there are no health conditions for which there is reliable evidence that homeopathy is effective, noting that the studies were generally small and of poor quality.

Re-analysis of the Shang meta-analysis

Lüdtke and Rutten, whose affiliations include a foundation funding complementary medicine research and an association of Dutch homeopathic physicians, re-analyzed the 21 higher-quality trials. They found an odds ratio of 0.76 (0.59 to 0.99), and showed that results shifted with the threshold used to define large trials. Shang's negative result was mainly driven by one trial in 400 long-distance runners, and they judged the conclusions less definite than presented.

Disagreement over the Australian thresholds

The NHMRC document says studies were treated as sufficiently large only when they had more than 150 participants, and that a Jadad quality score below 5 could signal serious bias. A 2021 review by a homeopathy educator criticized these thresholds as arbitrary and not stated in the executive summary. The thresholds appear in the paper's appendix. Both positions are reported here, and this page does not take a view on the further allegations made in that review.

Condition-level example: allergic rhinitis

A 2017 review of homeopathy for allergic rhinitis found 11 randomized trials, 8 at high risk of bias. Three trials of Galphimia glauca for seasonal rhinitis favored homeopathy for nasal symptoms at two weeks (risk ratio 1.48, 1.24 to 1.77), but the only trial judged reliable showed a small, non-significant effect. The authors urged caution and said the benefit of isopathic treatment was unclear.

Direct adverse effects

A systematic review of published case reports and case series found 38 reports, 30 of them describing direct adverse effects of remedies, in a total of 1,159 patients. Effects ranged from mild to severe and included four deaths, and the most common were allergic reactions and intoxications. Rhus toxicodendron was the remedy most often implicated. Because the evidence is case reports, it cannot show how frequent such events are.

NCCIH adds that some products contain substantial amounts of active ingredients, which can cause side effects or interact with medicines, and that some liquid products contain high levels of alcohol.

Delayed or replaced care

The same case-report review identified eight reports of harm caused by replacing conventional medicine with homeopathy. NHMRC advises that homeopathy should not be used to treat chronic or serious conditions, or those that could become serious, and that people may put their health at risk by rejecting or delaying treatments with good evidence of safety and effectiveness. NHMRC and NCCIH both advise people who use it to keep taking prescribed treatments and to tell their health practitioner.

Suitability

None of the sources reviewed lists formal contraindications for homeopathic remedies, and this page gives no individual advice. Educational information of this kind is not a substitute for assessment. New, worsening or serious symptoms are a reason to seek care from a registered health professional, and a decision to use homeopathy should not displace necessary treatment.