About Homeopathy » Evidence

Homeopathy's efficacy is unsupported by the collective weight of modern scientific research. The extreme dilutions used in homeopathic preparations usually leave none of the original material in the final product. The modern mechanism proposed by homeopaths, water memory, is considered implausible in that short-range order in water only persists for about 1 picosecond.^[97][98] Pharmacological effect without active ingredients is inconsistent with the observed dose-response relationships of conventional drugs,^[99] leaving only non-specific placebo effects^{[20][100][101]} or various novel explanations. The proposed rationale for these extreme dilutions - that the water contains the "memory" or "vibration" from the diluted ingredient - is counter to the laws of chemistry and physics, such as the law of mass action.^[97] The lack of convincing scientific evidence supporting its efficacy^[16] and its use of remedies without active ingredients have led to characterizations as pseudoscience and quackery,^{[5][7][102][103]} or, in the words of a 1998 medical review, "placebo therapy at best and quackery at worst."^[104] Use of homeopathy may delay or replace effective medical treatment, worsening outcomes or exposing the patients to increased risk.^{[21][22][105][106]}

Referring specifically to homeopathy, the British House of Commons Science and Technology Committee has stated:

^[3]

The National Center for Complementary and Alternative Medicine of the United States' National Institutes of Health states:

^[107]

High dilutions
The extremely high dilutions in homeopathy have been a main point of criticism. Homeopathic remedies are usually diluted to the point where there are no molecules from the original solution left in a dose of the final remedy.^[98] Homeopaths contend that the methodical dilution of a substance, beginning with a 10% or lower solution and working downwards, with shaking after each dilution, produces a therapeutically active remedy, in contrast to therapeutically inert water. Since even the longest-lived noncovalent structures in liquid water at room temperature are stable for only a few picoseconds,^[108] critics have concluded that any effect that might have been present from the original substance can no longer exist.^[109] No evidence of stable clusters of water molecules was found when homeopathic remedies were studied using NMR.^[110] Furthermore, since water will have been in contact with millions of different substances throughout its history, critics point out that water is therefore an extreme dilution of almost any conceivable substance. By drinking water one would, according to this interpretation, receive treatment for every imaginable condition.^[111] For comparison, ISO 3696: 1987 defines a standard for water used in laboratory analysis; this allows for a contaminant level of ten parts per billion, 4C in homeopathic notation. This water may not be kept in glass as contaminants will leach out into the water.^[112] Practitioners of homeopathy contend that higher dilutions produce stronger medicinal effects. This idea is inconsistent with the observed dose-response relationships of conventional drugs, where the effects are dependent on the concentration of the active ingredient in the body.^[99] This dose-response relationship has been confirmed in myriad experiments on organisms as diverse as nematodes,^[113] rats,^[114] and humans.^[115] Physicist Robert L. Park, former executive director of the American Physical Society, has noted that:

⁶⁰

^[100]

Park has also noted that, "to expect to get even one molecule of the 'medicinal' substance allegedly present in 30X pills, it would be necessary to take some two billion of them, which would total about a thousand tons of lactose plus whatever impurities the lactose contained".

The laws of chemistry state that there is a limit to the dilution that can be made without losing the original substance altogether.^[10] This limit, which is related to Avogadro's number, is roughly equal to homeopathic potencies of 12C or 24X (1 part in 10²⁴).^{[59][100][116]}

Scientific tests run by both the BBC's Horizon and ABC's 20/20 programs were unable to differentiate homeopathic dilutions from water, even when using tests suggested by homeopaths themselves.^[48][117]

Effectiveness
The effectiveness of homeopathy has been in dispute since its inception. One of the earliest double blind studies concerning homeopathy was sponsored by the British government during World War II in which volunteers tested the effectiveness of homeopathic remedies against diluted mustard gas burns.^[118] The methodological quality of the research base is generally low, with such problems as weaknesses in design or reporting, small sample size, and selection bias. No individual preparation has been unambiguously demonstrated to be different from a placebo.^[2][119] Further, as the quality of the trials become better, the evidence for homeopathy preparations being effective diminishes, and the highest-quality trials show that the remedies themselves have no effect.^{[15][19][38]:206} Abstract concepts within theoretical physics have been invoked to suggest explanations of how or why remedies might work, including quantum entanglement,^[120] the theory of relativity and chaos theory. However, the explanations are offered by nonspecialists within the field, and often include speculations that are incorrect in their application of the concepts and not supported by actual experiments.^[38]:255-6 A 2010 inquiry into the evidence base for homeopathy conducted by the United Kingdom's House of Commons Science and Technology Committee concluded that homeopathy is no more effective than placebo.^[3]

Meta-analyses
Meta-analyses, in which large groups of studies are analysed and conclusions drawn based on the results as a whole, have been used to evaluate the effectiveness of homeopathy. Early meta-analyses investigating homeopathic remedies showed slightly positive results among the studies examined, but such studies have warned that it was impossible to draw firm conclusions due to low methodological quality and difficulty in controlling for publication bias in the studies reviewed.^{[13][14][121]} One of the positive meta-analyses, by Linde, et al.,^[14] was later qualified by the authors, who wrote:

^[15]

In 2001, a meta-analysis of clinical trials on the effectiveness of homeopathy concluded that earlier clinical trials showed signs of major weakness in methodology and reporting, and that homeopathy trials were less randomized and reported less on dropouts than other types of trials.^[121]

In 2002, a review of systematic reviews found that higher-quality trials tended to have less positive results, to the point that those results were clinically irrelevant. Also, when taking collectively all the systematic reviews, there was no convincing evidence that any homeopathic remedy had better effects than placebo, and current evidence did not allow to recommend its usage in clinical treatment.^[2]

In 2005, a systematic review of the representation of homeopathy in the medical literature suggested that mainstream journals had a publication bias against clinical trials of homeopathy that showed positive results, and the opposite was the case for complementary and alternative medicine journals. The authors suggested that this could be due to an involuntary bias, or otherwise a submission bias, in which positive trials tend to be sent to CAM journals and negatives ones to mainstream journals.^[19] Review articles in both types of journal were not found to display this effect though most of the reviews published in CAM journals made no mention of the implausibility of homeopathy, whereas 9 out of 10 reviews in mainstream journals mentioned a lack of plausibility of homeopathy in the introduction.^[19]

In 2005, The Lancet medical journal published a meta-analysis of 110 placebo-controlled homeopathy trials and 110 matched medical trials based upon the Swiss government's Program for Evaluating Complementary Medicine, or PEK. The study concluded that its findings were compatible with the notion that the clinical effects of homeopathy are nothing more than placebo effects.^[4]

A 2006 meta-analysis of six trials evaluating homeopathic treatments to reduce cancer therapy side-effects following radiotherapy and chemotherapy found that there was "insufficient evidence to support clinical efficacy of homeopathic therapy in cancer care".^[122]

A 2007 systematic review of homeopathy for children and adolescents found that the evidence for attention-deficit hyperactivity disorder and childhood diarrhea was mixed. No difference from placebo was found for adenoid vegetation, asthma, or upper respiratory tract infection. Evidence was not sufficient to recommend any therapeutic or preventative intervention, and the delay in medical treatment may be harmful to the patient.^[21]

The Cochrane Library found insufficient clinical evidence to evaluate the efficacy of homeopathic treatments for asthma^[123] dementia,^[124] or for the use of homeopathy in induction of labor.^[125] Other researchers found no evidence that homeopathy is beneficial for osteoarthritis,^[126] migraines^{[127][128][129]} or delayed-onset muscle soreness.^[82]

Health organisations such as the UK's National Health Service,^[130] the American Medical Association,^[131] and the FASEB^[109] have issued statements of their conclusion that there is no convincing scientific evidence to support the use of homeopathic treatments in medicine.

Clinical studies of the medical efficacy of homeopathy have been criticised by some homeopaths as being irrelevant because they do not test "classical homeopathy".^[132] There have, however, been a number of clinical trials that have tested individualized homeopathy. A 1998 review^[133] found 32 trials that met their inclusion criteria, 19 of which were placebo-controlled and provided enough data for meta-analysis. These 19 studies showed a pooled odds ratio of 1.17 to 2.23 in favor of individualized homeopathy over the placebo, but no difference was seen when the analysis was restricted to the methodologically best trials. The authors 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." Jay Shelton, author of a book on homeopathy, has stated that the claim assumes without evidence that classical, individualized homeopathy works better than nonclassical variations.^[38]:209

Jack Killen, acting deputy director of the National Center for Complementary and Alternative Medicine, says homeopathy "goes beyond current understanding of chemistry and physics." He adds: "There is, to my knowledge, no condition for which homeopathy has been proven to be an effective treatment."^[16]

Explanations of effects
Science offers a variety of explanations for how homeopathy may appear to cure diseases or alleviate symptoms even though the remedies themselves are inert:^[38]:155-167

The placebo effect - the intensive consultation process and expectations for the homeopathic preparations may cause the effect
Therapeutic effect of the consultation - the care, concern and reassurance a patient experiences when opening up to a compassionate caregiver can have a positive effect on the patient's well-being.
Unassisted natural healing - time and the body's ability to heal without assistance can eliminate many diseases of their own accord
Unrecognized treatments - an unrelated food, exercise, environmental agent or treatment for a different ailment, may have occurred
Regression toward the mean - since many diseases or conditions are cyclical, symptoms vary over time and patients tend to seek care when discomfort is greatest, they may feel better anyway but because the timing of the visit to the homeopath they attribute improvement to the remedy taken
Non-homeopathic treatment - patients may also receive standard medical care simultaneous with homeopathic treatment, and the former is responsible for improvement
Cessation of unpleasant treatment - often homeopaths recommend patients stop getting medical treatment such as surgery or drugs, which can cause unpleasant side-effects; improvements are attributed to homeopathy when the actual cause is the cessation of the treatment causing side-effects in the first place, but the underlying disease remains untreated and still dangerous to the patient
Lifestyle changes - homeopaths often recommend diet and exercise, as well as limitations in alcohol or coffee consumption and stress reduction, all of which can increase health and decrease symptoms
Publishing standards, p-value - by definition, a positive outcome is seen as significant, if the probability of being due to chance rather than a real effect is less than 5%.^[134] As a result, about 1 in 20 tests can be expected to show an effect even though there is none.^[135]
Publication bias - researchers are more likely to submit positive trials for publication, and publishers are more likely to accept articles that report a positive finding.^{[136][137][138][139]}

Effects in other biological systems
While some articles have suggested that homeopathic solutions of high dilution can have statistically significant effects on organic processes including the growth of grain,^[140] histamine release by leukocytes,^[141] and enzyme reactions, such evidence is disputed since attempts to replicate them have failed.^{[142][143][144][145][146]}

In 1987, French immunologist Jacques Benveniste submitted a paper to the journal Nature while working at INSERM. The paper purported to have discovered that basophils, a type of white blood cell, released histamine when exposed to a homeopathic dilution of anti-immunoglobulin E antibody. The journal editors, sceptical of the results, requested that the study be replicated in a separate laboratory. Upon replication in four separate laboratories the study was published. Still sceptical of the findings, Nature assembled an independent investigative team to determine the accuracy of the research, consisting of Nature editor and physicist Sir John Maddox, American scientific fraud investigator and chemist Walter Stewart, and sceptic James Randi. After investigating the findings and methodology of the experiment, the team found that the experiments were "statistically ill-controlled", "interpretation has been clouded by the exclusion of measurements in conflict with the claim", and concluded, "We believe that experimental data have been uncritically assessed and their imperfections inadequately reported."^{[12][147][148]} James Randi stated that he doubted that there had been any conscious fraud, but that the researchers had allowed "wishful thinking" to influence their interpretation of the data.^[147]

Methodological and publication issues
Ben Goldacre published an article on homeopathy in The Lancet where he pointed to the high publication biases of alternative therapy journals, with very few articles reporting null results; ignoring meta-analytic studies in favour of cherry picked positive results; and the promotion of an observational study (that Goldacre described as "little more than a customer-satisfaction survey") as if it were more informative than a series of randomized trials. Goldacre also states that homeopaths who misrepresent scientific evidence to a scientifically illiterate public, have "...walled themselves off from academic medicine, and critique has been all too often met with avoidance rather than argument."^[149]

Ethics and safety
As homeopathic remedies usually contain only water and/or alcohol, they are thought to be generally safe. Only in rare cases are the original ingredients present at detectable levels. This may be due to improper preparation or intentional low dilution. Instances of arsenic poisoning have occurred after use of arsenic-containing homeopathic preparations.^[150] Zicam Cold remedy Nasal Gel, which contains 2X (1:100) zinc gluconate, reportedly caused a small percentage of users to lose their sense of smell;^[151] 340 cases were settled out of court in 2006 for 12 million U.S. dollars.^[152] In 2009, the FDA advised consumers to stop using three discontinued cold remedy products manufactured by Zicam because it could cause permanent damage to users' sense of smell.^[153] Zicam was launched without a New Drug Application (NDA) under a provision in the FDA's Compliance Policy Guide called "Conditions Under Which Homeopathic Drugs May be Marketed" (CPG 7132.15), but the FDA warned Zicam via a Warning Letter that this policy does not apply when there is a health risk to consumers.^[154]

Critics of homeopathy have cited other concerns over homeopathic medicine, most seriously cases of patients of homeopathy failing to receive proper treatment for diseases that could have been easily diagnosed and managed with conventional medicine and who have died as a result^[155][156] and the "marketing practice" of criticizing and downplaying the effectiveness of mainstream medicine.^[149][156] Homeopaths claim that use of conventional medicines will "push the disease deeper" and cause more serious conditions, a process referred to as "suppression".^[157] Some homeopaths (particularly those who are non-physicians) advise their patients against immunisation.^{[22][158][159]} Some homeopaths suggest that vaccines be replaced with homeopathic "nosodes", created from biological material such as pus, diseased tissue, bacilli from sputum or (in the case of "bowel nosodes") feces.^[160] While Hahnemann was opposed to such preparations, modern homeopaths often use them although there is no evidence to indicate they have any beneficial effects.^[161][162] Cases of homeopaths advising against the use of anti-malarial drugs have been identified.^{[105][163][164]} This puts visitors to the tropics who take this advice in severe danger, since homeopathic remedies are completely ineffective against the malaria parasite.^{[105][163][164]} Also, in one case in 2004, a homeopath instructed one of her patients to stop taking conventional medication for a heart condition, advising her on 22 June 2004 to "Stop ALL medications including homeopathic", advising her on or around 20 August that she no longer needed to take her heart medication, and adding on 23 August, "She just cannot take ANY drugs - I have suggested some homeopathic remedies ... I feel confident that if she follows the advice she will regain her health." The patient was admitted to hospital the next day, and died eight days later, the final diagnosis being "acute heart failure due to treatment discontinuation".^[165][166]

In 1978, Anthony Campbell, then a consultant physician at The Royal London Homeopathic Hospital, criticised statements made by George Vithoulkas to promote his homeopathic treatments. Vithoulkas stated that syphilis, when treated with antibiotics, would develop into secondary and tertiary syphilis with involvement of the central nervous system. Campbell described this as a thoroughly irresponsible statement that could mislead an unfortunate layperson into refusing conventional medical treatment. This claim echoes the idea that treating a disease with external medication used to treat the symptoms would only drive it deeper into the body and conflicts with scientific studies, which indicate that penicillin treatment produces a complete cure of syphilis in more than 90% of cases.^[37]

A 2006 review by W. Steven Pray of the College of Pharmacy at Southwestern Oklahoma State University recommends that pharmacy colleges include a required course in unproven medications and therapies, that ethical dilemmas inherent in recommending products lacking proven safety and efficacy data be discussed, and that students should be taught where unproven systems such as homeopathy depart from evidence-based medicine.^[167]

Edzard Ernst, the first Professor of Complementary Medicine in the United Kingdom and a former homeopathic practitioner,^{[168][169][170]} has expressed his concerns about pharmacists who violate their ethical code by failing to provide customers with "necessary and relevant information" about the true nature of the homeopathic products they advertise and sell:

"My plea is simply for honesty. Let people buy what they want, but tell them the truth about what they are buying. These treatments are biologically implausible and the clinical tests have shown they don't do anything at all in human beings. The argument that this information is not relevant or important for customers is quite simply ridiculous."^[171]

Michael Baum, Professor Emeritus of Surgery and visiting Professor of Medical Humanities at University College London (UCL), has described homoeopathy as a "cruel deception".^[172]

In an article entitled "Should We Maintain an Open Mind about Homeopathy?"^[173] published in the American Journal of Medicine, Michael Baum and Edzard Ernst - writing to other physicians - wrote that "Homeopathy is among the worst examples of faith-based medicine... These axioms [of homeopathy] are not only out of line with scientific facts but also directly opposed to them. If homeopathy is correct, much of physics, chemistry, and pharmacology must be incorrect.".

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