Homeopathy is a form of alternative medicine. Practitioners treat patients using highly diluted preparations believed to cause symptoms in healthy individuals similar to the undesired symptoms of the person treated. Scientific evidence has found homeopathy no more effective than a placebo.
German physician Samuel Hahnemann first stated the basic principle of homeopathy in 1796, known as the "law of similars."
This principle is: "let like be cured by like." Homeopathic remedies are prepared by serial dilution with shaking by forceful striking on an elastic body, which homeopaths term succussion.
Each dilution followed by succussion is assumed to increase the effectiveness. Homeopaths call this process potentization. Dilution often continues until none of the original substance remains.
Apart from the symptoms, homeopaths examine aspects of the patient's physical and psychological state, then homeopathic reference books known as repertories are consulted, and a remedy is selected based on the totality of symptoms.
In the context of homeopathy, the term remedy is used to refer to a substance which has been prepared with a particular procedure and intended for patient use; this differs from the generally accepted use of the word, which means "a medicine or therapy that cures disease or relieves pain".
Although a few isolated studies have seen positive results from homeopathic treatments, systematic reviews of published trials have failed to demonstrate efficacy.
Higher quality trials tend to report results that are less positive, and most positive studies have not been replicated. Many have methodological problems preventing them from being considered unambiguous evidence of homeopathy's efficacy. The lack of convincing scientific evidence to support homeopathy's efficacy and its use of remedies lacking active ingredients have caused homeopathy to be described as pseudoscience, quackery, and a "cruel deception".
Homeopathy is a vitalist philosophy that interprets diseases and sickness as caused by disturbances in a hypothetical vital force or life force. It sees these disturbances as manifesting themselves as unique symptoms. Homeopathy maintains that the vital force has the ability to react and adapt to internal and external causes, which homeopaths refer to as the law of susceptibility.
The law of susceptibility implies that a negative state of mind can attract hypothetical disease entities called miasms to invade the body and produce symptoms of diseases. However, Hahnemann rejected the notion of a disease as a separate thing or invading entity and insisted that it was always part of the "living whole". Hahnemann proposed homeopathy in reaction to the state of traditional western medicine at that time, which often was brutal and more harmful than helpful. Hahnemann coined the expression "allopathic medicine," which was used to pejoratively refer to traditional western medicine
Hahnemann observed from his experiments with cinchona bark, used as a treatment for malaria, that the effects he experienced from ingesting the bark were similar to the symptoms of malaria. He therefore decided that cure proceeds through similarity, and that treatments must be able to produce symptoms in healthy individuals similar to those of the disease being treated.
Through further experiments with other substances, Hahnemann conceived of the law of similars, otherwise known as "let like be cured by like" (Latin: similia similibus curentur) as a fundamental healing principle. He believed that by using drugs to induce symptoms, the artificial symptoms would stimulate the vital force, causing it to neutralise and expel the original disease and that this artificial disturbance would naturally subside when the dosing ceased. It is based on the belief that a substance that in large doses will produce symptoms of a specific disease will, in extremely small doses, cure it.
In 1828, Hahnemann introduced the concept of miasms; underlying causes for many known diseases. A miasm is often defined by homeopaths as an imputed "peculiar morbid derangement of [the] vital force". Hahnemann associated each miasm with specific diseases, with each miasm seen as the root cause of several diseases. According to Hahnemann, initial exposure to miasms causes local symptoms, such as skin or venereal diseases, but if these symptoms are suppressed by medication, the cause goes deeper and begins to manifest itself as diseases of the internal organs. Homeopathy maintains that treating diseases by directly opposing their symptoms, as is sometimes done in conventional medicine, is ineffective because all "disease can generally be traced to some latent, deep-seated, underlying chronic, or inherited tendency". The underlying imputed miasm still remains, and deep-seated ailments can be corrected only by removing the deeper disturbance of the vital force.
Hahnemann originally presented only three miasms, of which the most important was "psora" (Greek for itch), described as being related to any itching diseases of the skin, supposed to be derived from suppressed scabies, and claimed to be the foundation of many further disease conditions. Hahnemann believed psora to be the cause of such diseases as epilepsy, cancer, jaundice, deafness, and cataracts. Since Hahnemann's time, other miasms have been proposed, some replacing one or more of psora's proposed functions, including tubercular miasms and cancer miasms.
Hahnemann's miasm theory remains disputed and controversial within homeopathy even in modern times. In 1978, Anthony Campbell, then a consultant physician at The Royal London Homeopathic Hospital, criticised statements by George Vithoulkas claiming that syphilis, when treated with antibiotics, would develop into secondary and tertiary syphilis with involvement of the central nervous system. This conflicts with scientific studies, which indicate that penicillin treatment produces a complete cure of syphilis in more than 90% of cases. Campbell described this as "a thoroughly irresponsible statement that could mislead an unfortunate layman into refusing orthodox treatment".
The theory of miasms has been criticized as an explanation developed by Hahnemann to preserve the system of homeopathy in the face of treatment failures, and for being inadequate to cover the many hundreds of sorts of diseases, as well as for failing to explain disease predispositions as well as genetics, environmental factors and the unique disease history of each patient.
“Remedy” is a technical term in homeopathy that refers to a substance which has been prepared with a particular procedure and intended for patient use; it is not to be confused with the generally accepted use of the word, which means "a medicine or therapy that cures disease or relieves pain". Homeopathic practitioners rely on two types of reference when prescribing remedies: Materia medica and repertories. A homeopathic Materia medica is a collection of "drug pictures", organised alphabetically by “remedy,” that describes the symptom patterns associated with individual remedies. A homeopathic repertory is an index of disease symptoms that lists remedies associated with specific symptoms.
Homeopathy uses many animal, plant, mineral, and synthetic substances in its remedies. Examples include Arsenicum album (arsenic oxide), Natrum muriaticum (sodium chloride or table salt), Lachesis muta (the venom of the bushmaster snake), Opium, and Thyroidinum (thyroid hormone). Homeopaths also use treatments called nosodes (from the Greek nosos, disease) made from diseased or pathological products such as fecal, urinary, and respiratory discharges, blood, and tissue. Homeopathic remedies prepared from healthy specimens are called sarcodes.
Some modern homeopaths have considered more esoteric bases for remedies, known as imponderables because they do not originate from a material but from electromagnetic energy presumed to have been "captured" by alcohol or lactose. Examples include X-rays and sunlight. Today there are about 3,000 different remedies commonly used in homeopathy. Some homeopaths also use techniques that are regarded by other practitioners as controversial. These include paper remedies, where the substance and dilution are written on a piece of paper and either pinned to the patient's clothing, put in their pocket, or placed under a glass of water that is then given to the patient, as well as the use of radionics to prepare remedies. Such practices have been strongly criticised by classical homeopaths as unfounded, speculative, and verging upon magic and superstition.
In producing remedies for diseases, homeopaths use a process called dynamisation or potentisation whereby a substance is diluted with alcohol or distilled water and then vigorously shaken by ten hard strikes against an elastic body in a process called succussion. Hahnemann advocated using substances that produce symptoms like those of the disease being treated, but found that material doses intensified the symptoms and exacerbated the condition, sometimes causing dangerous toxic reactions. He therefore specified that the substances be diluted. Hahnemann believed that the succussion activated the vital energy of the diluted substance and made it stronger. To facilitate succussion, Hahnemann had a saddle-maker construct a special wooden striking board covered in leather on one side and stuffed with horsehair. Insoluble solids, such as quartz and oyster shell, are diluted by grinding them with lactose (trituration).
Three logarithmic potency scales are in regular use in homeopathy. Hahnemann created the centesimal or C scale, diluting a substance by a factor of 100 at each stage. The centesimal scale was favored by Hahnemann for most of his life. A 2C dilution requires a substance to be diluted to one part in one hundred, and then some of that diluted solution diluted by a further factor of one hundred. This works out to one part of the original substance in 10,000 parts of the solution. A 6C dilution repeats this process six times, ending up with the original material diluted by a factor of 100−6=10−12 (one part in one trillion or 1/1,000,000,000,000). Higher dilutions follow the same pattern. In homeopathy, a solution that is more dilute is described as having a higher potency, and more dilute substances are considered by homeopaths to be stronger and deeper-acting remedies. The end product is often so diluted that it is indistinguishable from the dilutant (pure water, sugar or alcohol).
In Hahnemann's time it was reasonable to assume that remedies could be diluted indefinitely, as the concept of the atom or molecule as the smallest possible unit of a chemical substance was just beginning to be recognized.
The greatest dilution that is reasonably likely to contain even one molecule of the original substance is 12C.
Some homeopaths developed a decimal scale (D or X), diluting the substance to ten times its original volume each stage. The D or X scale dilution is therefore half that of the same value of the C scale; for example, "12X" is the same level of dilution as "6C". Hahnemann never used this scale but it was very popular throughout the 19th century and still is in Europe. This potency scale appears to have been introduced in the 1830s by the American homeopath, Constantine Hering.
|X Scale, D Scale||C Scale||Ratio||Note|
|1X, D1||—||1:10||described as low potency|
|2X, D2||1C||1:100||called higher potency than 1X by homeopaths|
|8X, D8||4C||10−8|| |
|24X, D24||12C||10−24||Has a 60% probability of containing one molecule of original material if one mole of the original substance was used.|
|60X, D60||30C||10−60||Dilution advocated by Hahnemann for most purposes; patient would need to consume 1041 pills (a billion times the mass of the Earth), or 1034 gallons of liquid remedy (10 billion times the volume of the Earth) to consume a single molecule of the original substance |
Moreover, since even in a 15C solution there would very likely be no molecules of the original substance left, the 30C solution would probably contain no molecules of water that had come into contact with the original substance.
|400X, D400||200C||10−400||Dilution of popular homeopathic flu remedy Oscillococcinum|
|Note: the "X scale" is also called "D scale". 1X = D1, 2X = D2, etc.|
Critics and advocates of homeopathy alike commonly attempt to illustrate the dilutions involved in homeopathy with analogies. Hahnemann is reported to have joked that a suitable procedure to deal with an epidemic would be to empty a bottle of poison into Lake Geneva, if it could be succussed 60 times. Another example given by a critic of homeopathy states that a 12C solution is equivalent to a "pinch of salt in both the North and South Atlantic Oceans", which is approximately correct. One third of a drop of some original substance diluted into all the water on earth would produce a remedy with a concentration of about 13C. A popular homeopathic treatment for the flu is a 200C dilution of duck liver, marketed under the name Oscillococcinum. As there are only about 1080 atoms in the entire observable universe, a dilution of one molecule in the observable universe would be about 40C. Oscillococcinum would thus require 10320 more universes to simply have one molecule in the final substance. The high dilutions characteristically used are often considered to be the most controversial and implausible aspect of homeopathy.
Not all homeopaths advocate extremely high dilutions. Many of the early homeopaths were originally doctors and generally used lower dilutions such as "3X" or "6X", rarely going beyond "12X". The split between lower and higher dilutions followed ideological lines. Those favoring low dilutions stressed pathology and a strong link to conventional medicine, while those favoring high dilutions emphasised vital force, miasms and a spiritual interpretation of disease. Some products with such relatively lower dilutions continue to be sold, but like their counterparts, they have not been conclusively demonstrated to have any effect beyond that of a placebo.
Hahnemann experimented on himself and others for several years before using remedies on patients. His experiments did not initially consist of giving remedies to the sick, because he thought that the most similar remedy, by virtue of its ability to induce symptoms similar to the disease itself, would make it impossible to determine which symptoms came from the remedy and which from the disease itself. Therefore, sick people were excluded from these experiments. The method used for determining which remedies were suitable for specific diseases was called proving, after the original German word Prüfung, meaning "test". A homeopathic proving is the method by which the profile of a homeopathic remedy is determined.
At first Hahnemann used material doses for provings, but he later advocated proving with remedies at a 30C dilution, and most modern provings are carried out using ultradilute remedies in which it is highly unlikely that any of the original molecules remain.
During the proving process, Hahnemann administered remedies to healthy volunteers, and the resulting symptoms were compiled by observers into a drug picture. The volunteers were observed for months at a time and made to keep extensive journals detailing all of their symptoms at specific times throughout the day.
They were forbidden from consuming coffee, tea, spices, or wine for the duration of the experiment; playing chess was also prohibited because Hahnemann considered it to be "too exciting", though they were allowed to drink beer and encouraged to exercise in moderation. After the experiments were over, Hahnemann made the volunteers take an oath swearing that what they reported in their journals was the truth, at which time he would interrogate them extensively concerning their symptoms.
Provings have been described as important in the development of the clinical trial, due to their early use of simple control groups, systematic and quantitative procedures, and some of the first application of statistics in medicine. The lengthy records of self-experimentation by homeopaths have occasionally proven useful in the development of modern drugs: For example, evidence that nitroglycerin might be useful as a treatment for angina was discovered by looking through homeopathic provings, though homeopaths themselves never used it for that purpose at that time.
The first recorded provings were published by Hahnemann in his 1796 Essay on a New Principle. His Fragmenta de Viribus (1805) contained the results of 27 provings, and his 1810 Materia Medica Pura contained 65. For James Tyler Kent's 1905 Lectures on Homoeopathic Materia Medica, 217 remedies underwent provings and newer substances are continually added to contemporary versions.
Though the proving process has superficial similarities with clinical trials, it is fundamentally different in that the process is subjective, not blinded, and modern proving are unlikely to use pharmacologically active levels of the substance under proving. As early as 1842, Holmes noted that provings were impossibly vague, and that the purported effect was not repeatable among different subjects.
Homeopaths generally begin with detailed examinations of their patients' histories, including questions regarding their physical, mental and emotional states, their life circumstances and any physical or emotional illnesses. The homeopath then attempts to translate this information into a complex formula of mental and physical symptoms, including likes, dislikes, innate predispositions and even body type.
From these symptoms, the homeopath chooses how to treat the patient. A compilation of reports of many homeopathic provings, supplemented with clinical data, is known as a homeopathic materia medica. But because a practitioner first needs to explore the remedies for a particular symptom rather than looking up the symptoms for a particular remedy, the homeopathic repertory, which is an index of symptoms, lists after each symptom those remedies that are associated with it. Repertories are often very extensive and may include data extracted from multiple sources of materia medica. There is often lively debate among compilers of repertories and practitioners over the veracity of a particular inclusion.
The first symptomatic index of the homeopathic materia medica was arranged by Hahnemann. Soon after, one of his students Clemens von Bönninghausen, created the Therapeutic Pocket Book, another homeopathic repertory.
The first such homeopathic repertory was Georg Jahr's Symptomenkodex, published in German (1835), which was then first translated to English (1838) by Constantine Hering as the Repertory to the more Characteristic Symptoms of Materia Medica. This version was less focused on disease categories and would be the forerunner to Kent's later works. It consisted of three large volumes. Such repertories increased in size and detail as time progressed.
Some diversity in approaches to treatments exists among homeopaths.
Classical homeopathy generally involves detailed examinations of a patient's history and infrequent doses of a single remedy as the patient is monitored for improvements in symptoms, while clinical homeopathy involves combinations of remedies to address the various symptoms of an illness.
The list of ingredients seen on remedies may confuse consumers into believing that the product actually contains those ingredients. According to normal homeopathic practice, remedies are prepared starting with active ingredients that are often serially diluted to the point where the finished product no longer contains any biologically "active ingredients" as that term is normally defined.
James Randi and the 10:23 campaign groups demonstrated the lack of active ingredients in homeopathic products by taking large overdoses. None of the hundreds of demonstrators in the UK, Australia, New Zealand, Canada and the US were injured and "no one was cured of anything, either".
While the lack of active compounds is noted in most homeopathic products, there are some exceptions such as Zicam Cold Remedy, which is marketed as an "unapproved homeopathic" product. It contains a number of highly diluted ingredients that are listed as "inactive ingredients" on the label. Some of the homeopathic ingredients used in the preparation of Zicam are galphimia glauca, histamine dihydrochloride (homeopathic name, histaminum hydrochloricum), luffa operculata, and sulfur. Although the product is marked "homeopathic" it does contain two ingredients that are only "slightly" diluted: zinc acetate (2X = 1/100 dilution) and zinc gluconate (1X = 1/10 dilution), which means that both are present in a concentration that contains biologically active ingredients. In fact, they are strong enough to have caused some people to lose their sense of smell, a condition termed anosmia. This illustrates why taking a product marked "homeopathic", especially an overdose, can still be dangerous because it may contain biologically active ingredients, though as discussed previously, most homeopathic preparations contain no active ingredients. Because the manufacturers of Zicam label themselves as a homeopathic product (despite the relatively high concentrations of active ingredients), it is exempted from FDA regulation by the Dietary Supplement Health and Education Act of 1994 (DSHEA).
Isopathy is a therapy derived from homeopathy and was invented by Johann Joseph Wilhelm Lux in the 1830s. Isopathy differs from homeopathy in general in that the remedies, known as "nosodes", are made up either from things that cause the disease or from products of the disease, such as pus. Many so-called "homeopathic vaccines" are a form of isopathy.
Flower remedies can be produced by placing flowers in water and exposing them to sunlight. The most famous of these are the Bach flower remedies, which were developed by the physician and homeopath Edward Bach. Although the proponents of these remedies share homeopathy's vitalist world-view and the remedies are claimed to act through the same hypothetical "vital force" as homeopathy, the method of preparation is different. Bach flower remedies are prepared in "gentler" ways such as placing flowers in bowls of sunlit water, and the remedies are not succussed. There is no convincing scientific or clinical evidence for flower remedies being effective.
The idea of using homeopathy as a treatment for other animals, termed veterinary homeopathy, dates back to the inception of homeopathy; Hahnemann himself wrote and spoke of the use of homeopathy in animals other than humans. The FDA has not approved homeopathic products as veterinary medicine in the U.S. In the UK, veterinary surgeons who use homeopathy belong to the Faculty of Homeopathy and/or to the British Association of Homeopathic Veterinary Surgeons. Animals may be treated only by qualified veterinary surgeons in the UK and some other countries. Internationally, the body that supports and represents homeopathic veterinarians is the International Association for Veterinary Homeopathy. The use of homeopathy in veterinary medicine is controversial, as there has been little scientific investigation and current research in the field is not of a high enough standard to provide reliable data. Other studies have also found that giving animals placebos can play active roles in influencing pet owners to believe in the effectiveness of the treatment when none exists.
Electrohomeopathy was a 19th century practice combining homeopathy with electric treatment.
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. Pharmacological effect without active ingredients is inconsistent with the observed dose-response relationships of conventional drugs, leaving only non-specific placebo effects 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. The lack of convincing scientific evidence supporting its efficacy and its use of remedies without active ingredients have led to characterizations as pseudoscience and quackery, or, in the words of a 1998 medical review, "placebo therapy at best and quackery at worst." Use of homeopathy may delay or replace effective medical treatment, worsening outcomes or exposing the patients to increased risk.
Referring specifically to homeopathy, the British House of Commons Science and Technology Committee has stated:
In the Committee’s view, homeopathy is a placebo treatment and the Government should have a policy on prescribing placebos. The Government is reluctant to address the appropriateness and ethics of prescribing placebos to patients, which usually relies on some degree of patient deception. Prescribing of placebos is not consistent with informed patient choice - which the Government claims is very important - as it means patients do not have all the information needed to make choice meaningful.Beyond ethical issues and the integrity of the doctor-patient relationship, prescribing pure placebos is bad medicine. Their effect is unreliable and unpredictable and cannot form the sole basis of any treatment on the NHS.
The National Center for Complementary and Alternative Medicine of the United States' National Institutes of Health states:
Homeopathy is a controversial area of CAM because a number of its key concepts are not consistent with established laws of science (particularly chemistry and physics). Critics think it is implausible that a remedy containing a miniscule amount of an active ingredient (sometimes not a single molecule of the original compound) can have any biological effect—beneficial or otherwise. For these reasons, critics argue that continuing the scientific study of homeopathy is not worthwhile. Others point to observational and anecdotal evidence that homeopathy does work and argue that it should not be rejected just because science has not been able to explain it.[
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. 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, critics have concluded that any effect that might have been present from the original substance can no longer exist. No evidence of stable clusters of water molecules was found when homeopathic remedies were studied using NMR.
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.
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. This dose-response relationship has been confirmed in myriad experiments on organisms as diverse as nematodes, rats, and humans.
Physicist Robert L. Park, former executive director of the American Physical Society, has noted that:
since the least amount of a substance in a solution is one molecule, a 30C solution would have to have at least one molecule of the original substance dissolved in a minimum of 1,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000 [or 1060] molecules of water. This would require a container more than 30,000,000,000 times the size of the Earth.
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. This limit, which is related to Avogadro's number, is roughly equal to homeopathic potencies of 12C or 24X (1 part in 1024).
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. 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. 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. Abstract concepts within theoretical physics have been invoked to suggest explanations of how or why remedies might work, including quantum entanglement, 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.
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. One of the positive meta-analyses, by Linde, et al., was later qualified by the authors, who wrote:
The evidence of bias [in homeopathic trials] weakens the findings of our original meta-analysis. Since we completed our literature search in 1995, a considerable number of new homeopathy trials have been published. The fact that a number of the new high-quality trials...have negative results, and a recent update of our review for the most "original" subtype of homeopathy (classical or individualized homeopathy), seem to confirm the finding that more rigorous trials have less-promising results. It seems, therefore, likely that our meta-analysis at least overestimated the effects of homeopathic treatments.
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.
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.
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. 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.
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.
A 2006 meta-analysis of six trials evaluating homeopathic treatments to reduce cancer therapy side-effects following radiotherapy and chemotherapy found "encouraging but not convincing" evidence in support of homeopathic treatment. Their analysis concluded that there was "insufficient evidence to support clinical efficacy of homeopathic therapy in cancer care".
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.
The Cochrane Library found insufficient clinical evidence to evaluate the efficacy of homeopathic treatments for asthma dementia, or for the use of homeopathy in induction of labor. Other researchers found no evidence that homeopathy is beneficial for osteoarthritis, migraines or delayed-onset muscle soreness.
Health organisations such as the UK's National Health Service, the American Medical Association, and the FASEB 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". There have, however, been a number of clinical trials that have tested individualized homeopathy. A 1998 review 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.
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."
While some articles have suggested that homeopathic solutions of high dilution can have statistically significant effects on organic processes including the growth of grain, histamine release by leukocytes, and enzyme reactions, such evidence is disputed since attempts to replicate them have failed.
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 and magician 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." 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.
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."