Homeopathy/PreviousVersion

Homeopathy or homoeopathy—from the Greek hómoios (similar) and páthos (suffering)—is a system of alternative medicine based on the idea that substances known to cause particular combinations of symptoms can also, in low and specially prepared doses, help to cure diseases that cause similar symptoms.

Homeopathic remedies are intended to stimulate the body's natural healing processes. Homeopathy aims more at healing the patient by restoring balance than at treating the disease. Hygiene and diet are stressed as well as the use of homeopathic remedies. The rationale often involves discussion of "vital force"; in this homeopathy has much in common with other vitalist thought.

Two basic ideas in homeopathy are the principle of similars, sometimes stated as "like cures like", and the principle of infinitisimals, the idea that remedies become more potent as they are diluted. To discover remedies homeopaths conduct provings— small doses of substances are administered to volunteers and the dosage increased until symptoms appear. The symptoms are carefully noted and later used as the basis for applying a particular remedy in a given case. Preparation of remedies is a two-step process which homeopaths refer to as potentizing. The ingredients are first diluted and then succussed (shaken or otherwise agitated); generally this is an iterative process involving several repetitions of the alternating pair of steps.

Homeopathy is well established worldwide; both homeopathic practitioners and over-the-counter homeopathic remedies are widely available. Many national health insurance schemes include homeopathic treatments among the things they will pay for, and some medical doctors sometimes prescribe homeopathic remedies. There have been national and international homeopathic associations since the 19th century. See our external links for a list.

That said, the consensus of medical and scientific judgment is that homeopathy is unfounded. Most importantly, there is little, if any, objective evidence that homeopathy is effective. Neither of the main homeopathic principles — similars and infinitisimals — makes sense to the critical scientific mind. The "principle of similars" appears to be merely an appeal to sympathetic magic, or at best an over-generalisation of a principle that actually applies in only a few cases. The "principle of infinitisimals" contradicts both common sense and scientific results; there is no plausible mechanism to explain how the remedies might work, given that many of them are so dilute that they contain not a single molecule of the active ingredient. See our external links for some strongly critical assessments.

To most physicians and scientists, it is utterly obvious that a patient whose body is infected with a microbe needs adequate doses of a medicine which kills that microbe. There is just no room in this worldview for the idea that miniscule doses of a substance chosen by criteria unrelated to the microbe could have any useful effect.

Homeopaths have rejoinders to all the above. In particular, they claim that many of the studies in which homeopathy appears no more effective than a placebo are methodologically flawed — they either did not follow proper homeopathic procedure in preparing the remedies or did not apply them properly, with due attention by a skilled practitioner to matching the remedy to the ailment. Of course, these arguments do not apply to over-the-counter products based on homeopathic remedies, but that case is often ignored in the discussion. If one accepts the homeopathic assertion — which is vigorously seconded by some of their patients though not by scientific studies — that their remedies, properly applied, do work, then their principles become credible as well. The idea of memory of water is used to explain the effects of tiny doses.

Homeopaths point to a long safety record for their very dilute remedies and even those skeptical of their claims do not doubt the safety of those remedies – an inert substance is not going to harm anyone. The concern is that people who use homeopathy as an alternative to medical care take additional risk when they forego conventional treatment for serious illness such as anti-inflammatories and bronchodilators for asthma, or do not receive established preventive treatments, such as vaccines or anti-malarial drugs.

Principles

Some principles of homeopathy have been used in various forms in various medical systems for thousands of years in many diverse cultures, but they were first methodically set out by a German physician, Samuel Hahnemann (1755–1843), who observed that a medicine sometimes evoked symptoms similar to those of the illness for which it was prescribed. Homeopaths also contend that the "principle of similars" (treating "like" with "like") also serves as the basis for vaccination and allergy desensitation shots, two of the few methods in modern medicine that augment immune response to either prevent or treat disease, while non-homeopaths assert that these modern medical treatments are not based on any homeopathic principle but on specific immunological and allergy research. Related maxims such as the "principle of similars" are common in anthropological literature, and also are called sympathetic magic.

In traditional homeopathic theory, every person has a "vital force", with the power to promote healing and/or maintain good health. Homeopaths believe that this "vital force" is akin to what physiologists would call the body's "defense systems" or to qi in traditional Chinese medicine. In this theory, the signs and symptoms of a disease reflect efforts of the body to counter infection, or to resist damage from environmental toxins or from various stresses. Homeopathic treatment – it is claimed – attempts to strengthen this "vital force" with the help of remedies that are chosen for their ability (in large doses) to provoke the very symptoms that the remedy is intended to heal by stimulating the natural healing processes with the help of sub-physiological doses of a remedy.

"Classical homeopathy" or "Hahnemannian homeopathy" refers to the original principles of this medical system in which a single remedy is chosen according to the physical, emotional, and mental symptoms that the sick individual is experiencing rather than only the diagnosis of a disease. "Commercial" or "user-friendly" homeopathy refers to the use of a mixture of remedies in a single formula containing individual ingredients that are generally chosen by the manufacturer for treating specific ailments.

Overview

Homeopaths assert that the overall body of evidence for homeopathy, including trials of efficacy, basic sciences research, historical usage of homeopathic medicines in the treatment of people in various infectious disease epidemics and cost-effectiveness studies provide reasonable evidence for its benefits. Generally, natural scientists and medical doctors doubt that homeopathic treatments have any efficacy. They regard the evidence in support of efficacy as extremely weak, and point out that the claims made regarding homeopathy's underlying mechanism require an extraordinary level of proof to overcome their inherent impplausibility.

Many famous people over the past 200 years have been users and advocates of homeopathy, and it is an important thread in the history of medicine. The growth of homeopathy in the 19th century influenced how conventional medicine organised and how it came to formulate its present vision of evidence-based medicine, in contrast to practice based on individual clinical experience.

Homeopathic remedies are used by many people throughout the world, and homeopathy generally scores highly in "patient satisfaction" surveys. In the U.K. for instance, a survey cited by the British Homeopathic Association found that 15% of the public "trust" homeopathy. It also found higher percentages of trust in homeopathy in other countries: 58% Brazil, 53% Chile, 49% Saudi Arabia, 40% France, 28% Russia, 27% Germany, and 18% USA. That said, patient satisfaction and strength of public support for a treatment does not count as scientific evidence—just because a lot people believe something to work does not make it work (see argumentum ad populum).

Scientists and medical professionals are also often interested in homeopathy, especially in why homeopathy is so widely used when they regard it as having no rational foundation. They are interested too in why some studies appear to have positive outcomes—do these reflect real efficacy, or can they be accounted for by flaws in study design or in statistical analysis, or "publication bias"—the tendency for small studies with chance positive outcomes to be published while studies with negative or inconclusive outcomes are not. They also are interested in whether positive results against expectation sometimes reflect manipulation of data or perhaps even fraud.

Historical origins

The early Greek physician Hippocrates of Cos (c. 450 BCE - 380 BCE), who is considered to be the "father of medicine", is also claimed by homeopaths as a pioneer in their own tradition — because Hippocrates taught that "Natural forces within us are the true healers of disease," and because he thought that some diseases could be cured by the same things that caused them. In the late 18th century, this theory was coupled with a method to indicate what symptoms a substance causes and thereby what a particular medicine might cure. This method was developed by the German physician Samuel Hahnemann with his method of "provings"—studies of the effects, in humans, of high dosages.

In 1783, disillusioned with the medicine of his time and the many toxic effects of its treatments, Hahnemann gave up his medical practice and devoted himself to translating medical books, including many of the leading textbooks of the day. Among them was the Treatise on Materia Medica (1789) by William Cullen, the leading physician of the 18th century. Cullen had written that cinchona bark (which contains quinine) was effective in treating malaria because of its bitter and astringent properties. Hahnemann questioned this theory because he knew that other substances were as bitter and astringent, but had no therapeutic value in this deadly disease.

Hahnemann observed from his experiments with cinchona bark (then used as a treatment for malaria) that the effects he experienced from ingesting the bark were similar to the symptoms of malaria. He inferred that cure proceeds through similarity, and that effective treatments produce symptoms in healthy individuals similar to those of the disease being treated. Hahnemann observed similar results with other substances, and so conceived of the law of similars, otherwise known as "let like be cured by like" (Latin: similia similibus curentur) as a fundamental principle. He believed that, by inducing a syndrome of symptoms similar to the disease, the vis medicatrix naturae or natural healing processes of the body would be stimulated enough to neutralise the original disease and that this artificial disturbance would naturally subside when the remedy was no longer taken. It is based on the idea that a substance that in large doses will produce symptoms of a specific disease will, in extremely small doses, cure it. From these ideas, he developed a new system of health care as an alternative to the often toxic and ineffective drugs and treatments offered by conventional physicians of the time.

Hahnemann named his system "homoeopathy" (meaning "like disease") - but most people now spell it "homeopathy" - and coined the term "allopathy" ("different than disease") to refer to the conventional medicine of the day, justifiably referred to as heroic medicine because its physicians used large doses of highly toxic compounds to combat disease, and procedures such as bloodletting and leeching. Its drugs were sometimes "similar," sometimes "opposite," but usually just "different" to the symptoms of the sick person.

For the first two decades, Hahnemann used "crude" doses of medicinal substances ("crude", in homeopathic use, means doses that still contain some of the original ingredient). He strove to find the lowest doses at which his remedies would still be effective, as he thought this the best way to avoid any adverse side-effects. It seemed that reducing the dose did not reduce the effectiveness, and he concluded that his remedies worked better the more he diluted them as long as he “potentized” them, i.e. serial dilution followed by vigorous shaking (succussion). Homeopathy thus became inextricably linked with this process of ultradilution—repeated dilution of substances followed by succussion. Hahnemann had no clear explanation as to how or why these potentized remedies might have benefits; he distrusted all theoretical explanations and argued that all that mattered was whether a treatment was therapeutically effective.. He believed that diseases were caused by "spirit-like derangements of the spirit-like power that animates the human body", beginning with 'indispositions' and that effective healing called for medicines that would stimulate this life force to reestablish homeostasis and health.

Homeopathy was introduced into the U.S.A. in 1825 by Hans Burch Gram, who had studied homeopathy in Europe. In 1830, the first homeopathic schools opened (the first in the U.S.A. opened in 1835, in Allentown, Pennsylvania), and throughout the 19th century dozens more appeared in Europe and the U.S.A. Hahnemann had been a prominent and respected public health reformer, and in the 1830's the Medical Society of the Country of New York had granted him honorary membership. However, the Society rescinded this when they realized the "ideological and financial threat" that homeopathy posed. In 1844, the first U.S. national medical association - the American Institute of Homoeopathy - was established. By the end of the 19th century, 8% of American medical practitioners were homeopaths, and there were 20 homeopathic medical colleges (including Boston University, New York Medical College, and the Universities of Ohio State, Iowa, Minnesota and Michigan) and more than 100 homeopathic hospitals in the U.S.A. One reason for the growing popularity of homeopathy was its relative success in combatting the infectious disease epidemics that raged at the time. Cholera, scarlet fever, typhoid fever, and yellow fever killed many people, but death rates in conventional hospitals were typically two- to eight-fold higher than in homeopathic hospitals for patients with these diseases.

In the early 20th century, the "Flexner Report" triggered major changes in American medical education. As a result, many medical schools and colleges, including those teaching homeopathy were closed down, while others became conventional medical schools (including Hahnemann Medical College, Boston University, New York Medical College, and Ohio State University). In the 1960s, the popularity of homeopathy began to revive again in the U.S.A, and a 1999 survey reported that over 6 million Americans had used homeopathy in the previous 12 months. According to the American Homeopathic Pharmaceutical Association, the 1995 retail sales of homeopathic remedies in the U.S.A. were estimated at $201 million and growing at 20% per year; the number of homeopathic practitioners in the U.S.A. increased from fewer than 200 in the 1970s to approximately 3,000 in 1996.

Homeopathic "provings"

Homeopathic practitioners determine the therapeutic indications for their remedies from provings, in which volunteers are given repeated doses of substances (usually in single-blind or double-blind protocols), and keep a diary of any apparent symptoms. The effects are recorded in textbooks, called Materia Medica and Repertory, or nowadays in expert system software. Homeopathic provings provide the basis to determine what a substance causes in overdose and thereby what it is thought to cure. The symptom complexes that these substances cause are used to compare with a patient's symptoms in order to select, as the appropriate most similar remedy, the substance whose effects are closest to the patient's symptoms—called the "simillimum". Homeopaths prescribe a remedy (in potentized doses) when a sick person has a syndrome of symptoms that resembles the syndrome of symptoms that it causes in drug proving.

In 2006, the U.K.’s licensing body, the Medicine and Healthcare Products Regulatory Agency, altered their regulations to permit homeopathic remedies to be advertised using homeopathic provings to support their claims (justifying phrasing such as “For the relief of...”. This elicited protests from scientists, who called it a departure from the principle that such claims should be justified by evidence of efficacy.

Homeopathic manufacture of remedies

In the U.S.A., the Homœopathic Pharmacopœia of the United States is a legally recognized handbook that describes how to manufacture homeopathic drugs. This reference is approved by the Food and Drug Administration (FDA), the governmental agency that regulates drugs. Medicines listed in the HPUS defines them as homeopathic drugs which grants them a different standard of drug regulation than conventional drugs and medical devices.

The FDA regulates homeopathic drugs differently from other drugs. Manufacturers of homeopathic drugs do not have to submit new drug applications to the FDA, and their products are exempt from good manufacturing practice requirements related to expiration dating, and from finished product testing for identity and strength. Homeopathic drugs in solid oral dosage form must have an imprint that identifies the manufacturer and which indicates that the drug is homeopathic.

In 1938, the federal Food, Drug, and Cosmetic Act, sponsored by New York Senator Royal Copeland, a former homeopathic medical school dean, gave the FDA the power to regulate drugs and granted legal recognition to the "Homeopathic Pharmacopeia of the United States" as a compendium of drugs. In contrast, non-homeopathic drugs for which a New Drug Application is required must be accompanied by approved evidence of safety and efficacy.

Any substance can become a homeopathic remedy if "drug provings" are first conducted to determine what it causes in overdose and therefore, according to homeopathic theory, what it can cure in potentized doses. Today, homeopaths use about 3,000 different remedies, made from plants, trees, fungi, and algae, as well as from a wide variety of mineral and animal sources. Even some unusual substances, called imponderables, are made into homeopathic remedies, including electricity, X-ray, and magnetic north and south poles.By convention, the first letter of the Latin-derived name of such preparations is capitalized. When the source is well-defined, the traditional name rather than chemical, International Nonproprietary Name or biological nomenclature, is preferred, such as Natrum muriaticum rather than sodium chloride.

Homeopathic remedies are available in several different forms (single medicine, homeopathic formula or complex medicines, and a limited number of external applications). Remedies for internal consumption come either in pill form or as liquid. Most do not require a doctor's prescription, but may need one if the dosage is in a non-potentized or low potency dose and if the substance is potentially toxic (in Europe, a medicine must be diluted at least 1:10 three times to be deemed homeopathic). In the U.S.A., if a homeopathic remedy is claimed to treat a serious disease such as cancer, it can be sold only by prescription. Only products sold for “self-limiting conditions”—colds, coughs, fever, headaches, and other minor health problems that are expected to go away on their own—can be sold without a prescription.

Preparation of homeopathic remedies

The most characteristic — and controversial — principle of homeopathy is that the efficacy of a remedy can be enhanced by a process known as "dynamization" or "potentization". In this process, liquids are diluted (with water or ethanol) and shaken by ten hard strikes against an elastic body ("succussion"), to get the next, higher, potency. For this, Hahnemann had a saddlemaker construct a wooden "striking board", covered in leather on one side and stuffed with horsehair. When insoluble solids such as oyster shell are used for remedies, they are diluted by grinding them with lactose ("trituration"). The original dilutions by Hahnemann used a 1 part in 100 (centesimal; "C" potencies), or 1 part in 50,000 (quintamillesimal; "LM" or "L" potencies). Dr Constantine Hering later introduced the Decimal potencies ("D" or "X" potencies). The dilution factor at each stage is 1:100 ("C" potencies), 1:50,000 ("LM" potencies) or 1:10 ("D" or "X" potencies) ; Hahnemann advocated $30C$ dilutions for most purposes (i.e. dilution by a factor of 100³⁰ = 10⁶⁰). It is extremely unlikely that even one molecule of the original substance would be present in a $30C$ dilution. Thus, remedies of a high "potency"' contain just water, but according to homeopaths, the structure of the water has been altered (see memory of water).

"Classical homeopathy" or "Hahnemannian homeopathy" refers to the original principles of this system in which a single remedy is chosen according to the physical, emotional, and mental symptoms that the sick individual is experiencing rather than only the diagnosis of a disease. "Commercial" or "user-friendly" homeopathy refers to the use of a mixture of remedies in a formula containing individual ingredients chosen by the manufacturer for treating specific ailments.

Many homeopathic remedies sold in health food stores and pharmacies are "low potencies," that is, doses that are 3X, 3C, 6X, 6C, 12X, and 12C, all of which, except the last dose, have material doses of the original substances in the medicine.

Similia similibus curentur : the law of similars

Similia similibus curentur or "let likes cure likes", is the assertion that a disease can be cured by remedies that (in macroscopic, milligram doses) produce the same symptoms as those of the disease. This "law of similars", is a guiding principle in homeopathy. Homeopaths consider that vaccination, and hormesis are analogous to homeopathy's law of similars and the use of small doses.

Scientists and medical doctors today do not think that the law of similars is generally true or useful, and they explain the efficacy of vaccination without referring to it. Physicians of the 19th century however did consider that it was useful. For example, Emil Adolph von Behring (1854-1917), who won the Nobel Prize in medicine in 1901 for discoveries that led to vaccines against tetanus and diphtheria, and who some consider to be the father of immunology, asserted that vaccination is, in part, derived from the homeopathic law of similars.

In spite of all scientific speculations and experiments regarding smallpox vaccination, Jenner’s discovery remained an erratic blocking medicine, till the biochemically thinking Pasteur, devoid of all medical classroom knowledge, traced the origin of this therapeutic block to a principle which cannot better be characterized than by Hahnemann’s word: homeopathic.

Although homeopathic remedies and vaccinations both use low doses of ingedients, the doses in remedies are very much lower than those in vaccines. Moreover, vaccines produce a measurable immune response (e.g., immunoglobulin production); homeopathic remedies do not. Thus conventional treatments involve application of measurable doses of substances, at levels known to activate a cellular response. In contrast, homeopathic preparations above the $24X$ ($12C$) potencies do not contain enough molecules to activate any known metabolic or signalling pathway.

There are many different mechanisms by which tolerance can develop - and exposure to repeated small doses does not always result in tolerance. A herpetologist who receives many small doses of snake venom may become tolerant to them, but a beekeeper may become hypersensitive to the venom and, after receiving a sting, go into anaphylaxis. This type of response to small doses is not predictable on an individual basis. Allergic desensitization and drug desensitization are sometimes used in conventional medicine to treat individuals who have a specific allergy to something that they cannot easily avoid. This involves exposing the patient repeatedly to tightly controlled doses, increasing the doses gradually over time. This treatment can be dangerous (because exposure of sensitive individuals to an allergen can produce anaphylaxis), and it has very inconsistent efficacy, so is normally only attempted when the allergy poses serious restrictions on the patient's normal life.

Homeopathy in practice

In some countries, homeopathic remedies are sold over-the-counter in both pharmacies and health food or other retail outlets. Some countries allow homeopaths to describe themselves in equivalent ways to doctors, with a system of qualification and oversight. In India, homeopathy has the status of a 'national system' of medicine. In addition, remedies are used by consumers all over the world for self-treatment of common self-limiting ailments and injuries. Some medical doctors, particularly in Germany, France, and several other European countries prescribe homeopathic remedies for a wide variety of both self-limiting conditions and serious diseases. Other physicians work with patients who self-prescribe homeopathic remedies or receive them from other practitioners.

There are no universal standards for homeopathic education, so licensing and regulation varies from country to country and from state to state within the U.S.A. In some countries, all (or virtually all) professionals that use homeopathic treatments are MDs (such as France, Spain, Argentina, Colombia). Some countries have exclusively homeopathic medical schools (India, Pakistan, Mexico etc.), some have naturopathic medicine colleges in which students are taught homeopathy as part of their curriculum (Germany has its "heilpraktica"/health practitioners; the U.S.A., Canada, and Australia have naturopathic medicine schools that include homeopathy), and some countries certify "professional homeopaths" who have attended homeopathic schools and who then pass independent examinations that grant "certification" as homeopaths. In the U.S.A., there is also a separate certification process available only to MDs and DOs (there are similar choices of certification available in the U.K. for medical doctors, who've done at least MBBS). Also in the U.S.A., naturopathic physicians have their own homeopathic certifying agency.

In Europe, homeopathic remedies are occasionally prescribed by many conventional physicians (often as placebos), including by 30-40% of French doctors and 20% of German doctors. Some homeopathic treatment is partly covered by public funds; for example, in France, 35% of the costs of homeopathic remedies prescribed by a medical doctor are reimbursed from health insurance. In the U.K., five homeopathic hospitals are funded by the National Health Service (NHS) and homeopathic remedies are sold over the counter. In 2007, the over-the-counter market in homeopathy was around £40million in the U.K. ; the total over-the-counter market was £1.2 billion in 1994. Family doctors in the U.K. issued 796 million prescriptions in 2007, of which 49,300 were for homeopathic remedies, down from 83,000 in 2005. In January 2008, it was reported that the NHS was progressively withdrawing funding for homeopathic treatments because of doubts about their efficacy . Of 248,000 registered practitioners of medicine in the U.K., about 400 are members of the Faculty of Homeopathy. However, in the U.K., anyone can declare themselves to be a homeopath and practice without any qualification ("common law" that allows freedom of choice in medical care in England has a long history)

In France and Denmark, licenses are required to diagnose any illness or to dispense any product whose purpose is to treat illness. In many countries, however, there are no specific legal regulations concerning homeopathy. In Austria, the public health service generally requires proof of effectiveness to reimburse medical treatments, but makes an exception for homeopathy. Almost 70% of all over-the-counter homeopathic remedies are sold in Western Europe. France is the largest market for homeopathic remedies in the world, worth over 300 million euros in 2003 (in a total over-the-counter drug market of over 770 billion euros), followed by Germany (200 million euros). The global self-medication market is estimated at 48.2 billion dollars (13.4% of the world pharmaceuticals market), of which sales of homeopathic remedies account for 0.3%.

In India, homeopathy has more than 200,000 registered practitioners and is recognised as one of the Indian "National Systems of Medicine" under the Department of AYUSH (Ayurveda, Yoga and Naturopathy, Unani, Siddha and Homeopathy), while conventional, western medical education is controlled by the Medical Council of India. About 10% of the Indian population depends solely on homeopathy for their health care needs. In India, it is illegal to practice as a homeopath without a license and professional qualifications.

A typical homeopathic visit

Homeopaths view illness as a systemic condition, a disturbance in the overall homeostasis of the total being and accordingly, consider that almost any sick person, may benefit from proper homeopathic treatment.

"homeopathy is designed to treat the whole person and can therefore be considered in almost any situation where a person's health is depleted."

As the American Institute of Homeopathy puts it in their "Standards of Practice": "The physician must remember that he is treating a patient who has some disorder; he is not prescribing for a disease entity." .

Patients often come to homeopaths with chronic problems that have not responded to conventional treatment. Some common ailments for which patients seek homeopathic care are eczema, chronic fatigue syndrome, asthma, migraine, irritable bowel syndrome, allergic disorders, arthritis, fibromyalgia, hypertension, Crohn's disease, premenstrual syndrome, rhinitis, anxiety and depression, but they also treat patients with serious diseases, including multiple sclerosis, chronic obstructive pulmonary disease, and cancer. and AIDS For gangrene, for example, homeopathic remedies are prescribed in the belief that they will strengthen a person's defenses and to initiate healing; a very different approach than medical therapy. Some of many homeopathic remedies for gangrene include Arsenicum Album, Secale (from rye/ergot), and Carbo vegetabilis (from charcoal).

When a homeopath is conducting an interview to characterise a patient's syndrome of symptoms, some "categories of change" are identified as important: (1) emotion (2) mentation (3) specific physical functioning (4) general physical changes (5) perception of self (6) relationships (7) spirituality (8) lifestyle (9) energy (10) dream content and tone (11) well-being (12) perceptions by others (13) life relationships (14) a sense of freedom or feeling less "stuck" (15) sleep (16) coping (17) ability to adapt (18) creativity (19) recall of past experiences

When deciding which remedy to prescribe, classical homeopaths place emphasis on the patient's unique symptoms and their psychological state. They gather this information from an interview, typically lasting from 15 minutes to two hours, with one or more follow-up consultations of 15 to 45 minutes. They assess how the patient experiences their disease—i.e. they give priority to the overall syndrome of symptoms and the unique and idiosyncratic symptoms, in contract to the conventional medical approach of trying to identify the causes of the disease. Their goal is to determine factors that might predispose the patient to disease, and find a treatment that will strengthen that patient's "overall constitution". After the interview, the homeopath consults the references described in the table on the right. Some homeopaths make quick prescriptions based on "keynotes"—the highlights of the best known characteristics of a remedy. The real challenge of homeopathic practice, though, is to find the remedy that best matches the patient's syndrome of physical and/or psychological symptoms—the "similimum". A fundamental reason for conflict between conventional medicine and homeopathy is that homeopathy rejects the concept of treatments that target mechanisms of disease, and instead uses remedies that target syndromes of symptoms that they believe strengthen a person's overall constitution. Some homeopathic protocols might look like the following:

1. A physician qualified in both homeopathy and conventional medicine, after diagnosing a chronic condition that does not indicate the need for medical urgency, might prescribe a homeopathic remedy rather than a conventional drug which he feels may be ineffective and/or likely to have side effects. Most physicians, however, are not homeopathically trained, and most homeopaths are not medically qualified.
2. Homeopaths recognize that trauma might require conventional medical attention but may complement the conventional treatment with homeopathy.
3. Homeopaths disagree with conventional medicine about the role of immunization and chemoprophylaxis for infectious diseases and prefer to prescribe remedies that they believe will strengthen a person's immune and defense system.
4. For some disease conditions, such as asthma and acute bronchitis, homeopathic remedies are often prescribed not only to alleviate chronic symptoms, but also to treat acute attacks. Remedies might also be used after an asthmatic episode with the intent to prevent recurrences.

The homeopathic treatment of acute problems does not need the same depth or breadth of interview as chronic conditions. According to homeopaths, because the symptoms of a common cold or a headache or an allergy vary from person to person, each may need a different remedy. However, they believe that people who experience an injury generally have similar symptoms, so they think that some homeopathic remedies might be routinely useful in such cases.

Homeopaths who practice "classical homeopathy" prescribe one remedy at a time—a remedy that best fits the overall syndrome of the patient. The same remedy might thus be prescribed for patients with very different diseases; conversely, patients suffering from the same disease may be prescribed different remedies. For example, hay fever would be treated with any of several remedies, usually based on the specific symptoms, but sometimes on the etiology of the allergy. Some common remedies are: Allium cepa (onion, which causes tears to flow and a clear burning nasal discharge that irritates the nostrils), Euphrasia (eyebright, which causes a clear and bland nasal discharge along with tears that burn and irritate the skin where the tears flow), Ambrosia (ragweed) and Solidago (goldenrod); ragweed and goldenrod are herbs whose pollen is aggravating to some hay fever sufferers. These remedies are commonly given during the acute symptoms of hay fever. At other times, a homeopath might treat these patients with a constitutional remedy based on the patient’s family history, health history, and present overall physical and/or psychological state, with the intent to strengthen the person’s general health.

Conflict with conventional medicine

James Tyler Kent and homeoprophylaxis Some homeopaths also believe that their treatments can prevent disease, a notion known as "'homeoprophylaxis". James Tyler Kent (1849-1916) was associated with the spread of homeopathy in the U.S.A., and much modern practice of homeopathy is based on his repertory, published in 1897. Kent denied the germ theory of infectious disease, declaring that "The microbe is not the cause of disease. We should not be carried away by these idle allopathic dreams and vain imaginations but should correct the Élan vital". Instead, he believed that illness had spiritual causes: "You cannot divorce medicine and theology. Man exists all the way down from his innermost spiritual, to his outermost natural." Kent promoted the idea that remedies could prevent diseases: "The great prophylactic is the homeopathic remedy. After working in an epidemic for a few weeks, you will find perhaps that half a dozen remedies are daily indicated and one in these remedies in a larger number of cases than any other. This one remedy seems to be the best suited to the general nature of the sickness. Now you will find that for prophylaxis there is required a less degree of similitude than is necessary for curing. A remedy will not have to be so similar to prevent disease as to cure it, and these remedies in daily use will enable you to prevent a large number of people from becoming sick. We must look to homeopathy for our protection as well as for our cure". Homeoprophylaxis has not received support from systematic trials and has no place in conventional medicine. Suggestions that homeopathic treatments are an effective alternative to vaccination are regarded as irresponsible by many public health professionals, and also by some professional homeopathic organizations; in the U.K., The Faculty for Homeopathy recognizes the importance of childhood vaccination and does not support the common use of homeopathic remedies in place of conventional travel vaccinations and for malaria prevention, warning travellers "that there is no evidence that these provide any degree of protection."

The theory underlying homeopathy is not considered plausible by most academic scientists in Europe and the U.S.A., and the treatment advice offered by homeopaths is in disagreement with conventional medicine.

Their view is that homeopathy exploits the placebo effect - i.e. that the only benefits are those induced by the power of suggestion, by arousing hope, and by alleviating anxiety. Placebos have played a large part in conventional medicine since their first deliberate use by William Cullen in the 18th century.

...we all recognise the strong placebo effect in, probably, all aspects of medical treatment, whether they are conventional or not" - Professor Tom Mead

Cullen used regular drugs as placebos, but at much lower doses than he expected to be effective, and "to comfort and please the patient" rather than with any hope of a specific effect.. Many modern physicians, however, consider it unethical to mislead their patients; rather than prescribing placebos themselves, some prefer to refer patients to regulated practitioners of alternative medicine.

Some homeopaths, especially with medical training, use conventional techniques to treat asthmatic and other respiratory medicine, but homeopathic methods for long-term care. One of the challenges is that the standard of medical therapy for asthma is to prevent inflammation, which commonly involves inhaled corticosteroids that are not absorbed beyond the respiratory system. Homeopaths assert that corticosteroids are immunosuppressant drugs that only provide temporary relief of asthma symptoms and may lead to more serious chronic disease and to increased chances of death. Medical opinion is that this assertion is uninformed scare-mongering. They advise that corticosteroids prevent inflammation that can have serious consequences and symptom relief is a result of this anti-inflammatory action. Inhaled corticosteroids that stay on the breathing passages and do not spread through the body are medically preferred to systemic corticosteroid therapy and thus reduce immune-suppressing effects of these drugs.

Most homeopaths believe that the fundamental causes of disease are internal and constitutional and that infectious disease is not just the result of infection but also of susceptibility. This leads them to avoid conventional treatments that suppress symptoms. Physicians accept that some disease is a disturbance in normal function, whether due to external, genetic, or internal reasons. However, they consider that most diseases are caused by a combination of external causes (such as viruses, bacteria, toxins, dietary deficiency, physical injury) and physiological dysfunction (including genetic defects and mutations such as those which trigger cancers). The main goal of conventional medicine is to eliminate these causes, although physicians often also use drugs to suppress the symptoms of a disease (to alleviate the pain, injury, and distress that they cause).

Whereas homeopaths emphasize that they provide remedies tailored to the individual patient, conventional medicine focuses on treatments with demonstrable efficacy when given in a standard form to many patients with a given disease. Large clinical trials also seek to identify subgroups of patients (identifiable by age, gender, ethnicity, lifestyle, comorbidities etc.) that are "responders" or "non responders" to a new treatment, to provide a rational basis for individualization of treatments. Conventional physicians have access to a very large repertoire of prescription drugs for this purpose (11,706 in the U.S. Food and Drug Administration Approved Drug Products with Therapeutic Equivalence Evaluations 26th Edition Electronic Orange Book (EOB)4 ) , a repertoire that is constantly changing as less effective drugs are replaced by better drugs.

Medical organizations' attitudes towards homeopathy

The American Medical Association (AMA) was founded in 1847, three years after the American Institute of Homeopathy. From the 1860s to the early 20th century, the AMA's ethical code forbade its members to consult with fellow MDs who practiced homeopathy. Today, the AMA is no longer overtly antagonistic to homeopathy, but their current policy statement says: "There is little evidence to confirm the safety or efficacy of most alternative therapies. Much of the information currently known about these therapies makes it clear that many have not been shown to be efficacious."

At present, only people credentialed in a conventional medical area of practice may join the American Institute of Homeopathy. Only professionals with a MD, DO, or DDS degree are eligible to be Active Members; advanced practice nurses and physician assistants are eligible to be Associate Members.

Some limited homeopathic treatment is available on Britain's National Health Service. The NHS funds homeopathic hospitals in Glasgow, Liverpool, Bristol and London and there are several NHS homeopathic clinics in Scotland, treating approximately 55,000 patients per year by some 600 doctors. In 2010 the British Medical Association voted in favour of stopping any use of NHS funds for homeopathy, and proposed that pharmacists should remove homeopathic remedies from their shelves to prevent them from being confused with medicines. However, the British health minister declared that doctors should be free to decide whatever treatment they think appropriate in individual cases, and so homeopathic care remains a (very small) part of the NHS.

In the U.S.A.,The National Center for Complementary and Alternative Medicine (NCCAM) administers public-funded research into alternative medicine . Their 2003 report on homeopathy (see here) asks: "Are there scientific controversies associated with homeopathy?", and replies: "Yes. Homeopathy is an area of complementary and alternative medicine (CAM) that has seen high levels of controversy and debate, largely because a number of its key concepts do not follow the laws of science (particularly chemistry and physics). It is debated how something that causes illness might also cure it. It has been questioned whether a remedy with a very tiny amount (perhaps not even one molecule) of active ingredient could have a biological effect, beneficial or otherwise. There have been some research studies published on the use of ultra-high dilutions (UHDs) of substances, diluted to levels compatible with those in homeopathy and shaken hard at each step of dilution. The results are claimed to involve phenomena at the molecular level and beyond, such as the structure of water, and waves and fields. Both laboratory research and clinical trials have been published. There have been mixed results in attempts to replicate them. Reviews have not found UHD results to be definitive or compelling. There have been some studies that found effects of UHDs on isolated organs, plants, and animals. There have been controversy and debate about these findings as well. Effects in homeopathy might be due to the placebo or other non-specific effect. There are key questions about homeopathy that are yet to be subjected to studies that are well-designed--such as whether it actually works for some of the diseases or medical conditions for which it is used, and if so, how it might work. There is a point of view that homeopathy does work, but that modern scientific methods have not yet explained why. The failure of science to provide full explanations for all treatments is not unique to homeopathy. Some people feel that if homeopathy appears to be helpful and safe, then scientifically valid explanations or proofs of this alternative system of medicine are not necessary." In 2008, NCCAM's acting deputy director, Jack Killen, said, in a Newsweek article, "There is, to my knowledge, no condition for which homeopathy has been proven to be an effective treatment." .

Safety and efficacy of homeopathy

In conventional medicine (see New Drug Application), the basic phases of evaluating a drug are determining if it causes dangerous effects in healthy volunteers, if it is adequately present in the body to achieve an effect, and if it is more effective than established treatments, against a disease. Not all trials are placebo controlled, but only those where there is no accepted treatment; new drugs must be compared with the best available existing treatment. See informed consent.

In conventional medicine, randomized controlled trials rely on statistical analysis of large groups of patients all of whom are given the same treatment to determine whether that treatment is effective. This conflicts with an approach that believes that treatments must be individually tailored to each patient. Some homeopathic trials do use some standardization, but not always to an extent which would make the trials statistically robust. Clinical trial specialists have proposed protocols to test "low responding" or individualized therapies in statistically valid clinical trials. For homeopathy, by having a group of people who identify as ill and asking a qualified homeopath to diagnose them - then having a homeopathic remedy given to a subset of them, and medicines that share the same physical properties but are homeopathically inert according to homeopaths (for instance, by using ordinary water rather than homeopathically diluted water in preparing the substance). This method thus tests the standard diagnostic method as the experimental treatment, rather than the specific medications. There have not been, however, many homeopathic trials using this method.

Few people question the safety issues in choosing homeopathic remedies, and the U.S. F.D.A. determines what dose is basically safe for over-the-counter sales of homeopathic remedies. However, homeopaths discourage the general public from using the homeopathic high potency remedies (the 200th potency and higher potencies) unless the person is adequately trained in homeopathy. Homeopaths warn the public that repeated doses of high potency remedies can lead the person to experience a "drug proving," a situation in which the person experiences symptoms akin to an overdose of the substance (the symptoms are generally known to resolve themselves shortly after the person stops taking the remedy).

Attempts to provide a scientific foundation for homeopathy

Homeopathy arose when many important concepts of modern chemistry and biology, such as molecules and germs, were understood poorly, if at all. In Hahnemann's day, many chemists believed that matter was infinitely divisible, so that it was meaningful to talk about dilution to any degree. The size of atoms was not calculated until 1865 (by Josef Loschmidt), but we now know that, for example, a teaspoon of seawater (roughly 5 ml) contains about 160 mg of NaCl. The molecular weight of NaCl is 58.4, so by Avogadro's number, , 58.4 g of NaCl (one mole) contains 6.02×10²³ molecules, and hence our teaspoon contains about 2×10²¹ molecules of NaCl. A 12C dilution of seawater will have about one molecule of NaCl per litre. Thus remedies diluted to more than about 12C are virtually certain to contain not even a single molecule of the initial substance. This is recognized by advocates of homeopathy, who assert that the healing power is not in the chemical action of molecules, but perhaps in the arrangement of the water molecules, giving rise to the expression "the memory of water".

In the homeopathic literature widely differing (and mutually inconsistent) explanations are proposed for this alleged memory. For instance, homeopaths point out that water is not simply a collection of molecules of H₂O, but contain isotopologues, molecules with different isotopic compositions such as HDO, D₂O and H₂¹⁸O. Mass spectroscopy can indeed detect different isotopologues, but their relative concentration is the same before and after homeopathic treatment—the concentration ratios can only be changed by nuclear reactions—so that the presence of isotopologues in water cannot explain its memory. Also the fact that the molecules H₂O appear in two proton-spin forms (ortho and para) has been suggested as a source of memory of water. These two spin forms, which appear in a ratio 3:1, are chemically non-distinguishable and are very difficult to separate or to convert into each other. It is therefore highly unlikely that a homeopathic treatment could change this ratio. Moreover, even if homeopathic tinctures could give somehow rise to ortho:para ratios other than 3:1, it requires much further explanation that these (chemically undetectable) ratios have different healing qualities.

Another suggestion is that double-distilled and deionized water contains trace amounts of contaminating ions. In particular, water, as a result of repeated vigorous shaking, might include dissolved atmospheric gases in the form of nanobubbles, molecular ions produced from water reacting with airborne contaminants, and silicates—tiny glass "chips". These possibilities are discussed in Ref. and Ref. But see for further discussion Ref. in which it is concluded that: "it [observed variation in NMR relaxation rates upon ultra dilution] might merely reflect a trivial air-dependent phenomenon, or an unsuspected bias, and should not be extrapolated to the so-called memory of water, often alleged to explain the effectiveness of homeopathy." In January 2009, Luc Montagnier, the Nobel Laureate French virologist who discovered HIV, claimed that the DNA of pathogenic bacteries and viruses massively dissolved in water emit radio waves that he can detect. This, he claimed, can also be used to detect the medicine in a homeopathic remedy. The claim has been received with skepticism in the scientific community..

Some homeopaths believe that there might be an effect of successive shaking on water structure leading to "clustering" of water molecules. This contradicts the dominant scientific view that motions in liquid water are on the picosecond (10⁻¹² second) time scale and that such clusters could not live longer than a few picoseconds.

People sometimes wonder if the water used to make homeopathic medicines already has other memory imprints from its history prior to use in medicine. However, the water used by homeopathic manufacturers undergoes double-distillation, a process that homeopaths contend eliminates or substantially reduces previous memory. This raises the question: how do homeopaths know that this reduction is sufficient? If the presence of homeopathic qualities is below detection threshold, then surely the absence of such qualities is also undetectable.

In brief, for homeopathy to receive serious scientific consideration, there must be plausible explanations for the following:

• how the process of manufacturing a homeopathic remedy could yield a biologically active substance
• why the principle of similars might apply in the case of homeopathic remedies
• how a biological mechanism could have evolved to recognize the specific nature of homeopathic remedies

There also needs to be

• compelling evidence for the efficacy of homeopathic remedies, evidence that cannot be explained by placebo effects

These stringent demands are often summarised by the maxim "Extraordinary claims require extraordinary proof".

Meanwhile, homeopaths complain that they are up against a double standard in medicine and science. They point out that there is a long history of conventional medical treatments that have been used long before any knowledge of their mechanism of action. Only relatively recently, for instance, has it been understood how aspirin works, but medical standards of evidence grow more strict. It is much less likely that a clinical trial will be approved, of a new medical drug, unless there is substantial knowledge of a plausible mechanism. In the U.S., homeopathic remedies are exempt from the clinical trial requirement.

Clinical trials testing the efficacy of homeopathic remedies

The "balance of evidence" as to whether homeopathy has any effects other than placebo effects depends on who is balancing the evidence. Homeopaths strongly value the evidence of their own experience in treating patients, supported by the satisfaction reported by their patients in surveys; they also state that most published clinical trials have shown some beneficial effects. A 1991 global meta-analysis of homeopathic clinical trials published in theBritish Medical Journal of 105 trials, 81 with positive outcomes, concluded that the placebo response could not explain the positive responses, saying "Based on this evidence we would be ready to accept that homoeopathy can be efficacious, if only the mechanism of action were more plausible Another meta-analysis published in the Lancet in 1997 similarly concluded that the results "were not compatible with the hypothesis that the effects of homoeopathy are completely due to placebo." Several meta-analyses evaluating the homeopathic treatment of specific diseases have also found positive results, including for childhood diarrhoea, some post-surgical conditions and respiratory allergies .

Conversely, other meta-analyses suggest that the effect from a homeopathic remedy was no better than a placebo The Cochrane Collaborationpublishes meta-analyses of trial results, and most of their analyses of homeopathy indicate no statistically significant benefit. The most supportive of their analyses is of Oscillococcinum for influenza and influenza-like syndromes. Cochrane Reviews did a meta-analysis of seven randomized controlled trials, three prevention trials (number of participants, $N=2265$) and four treatment trials, $(N=1194)$. This was a meta-analysis of seven randomized controlled trials, three prevention trials (number of participants, $N=2265$) and four treatment trials, $(N=1194)$. The authors found no evidence of any benefits in preventing influenza, but evidence of a small effect on the duration of symptoms.

In the U.K., the NHS recognizes that there have been about 200 randomised controlled trials evaluating homeopathy, some show efficacy of treatment and some don't. They conclude, "Despite the available research, it has proven difficult to produce clear clinical evidence that homeopathy works".

Homeopaths believe that such attitudes reflect bias against alternative medicine, and that because homeopathy does not lend itself to controlled trials, those with a negative outcome may be false negatives.

According to critics of homeopathy, published trials of homeopathic remedies have been mostly small and flawed in design and/or reporting, with flawed measuring techniques and difficulties in replicating results. Because of these problems, it is difficult to draw firm conclusions about whether homeopathy is effective for any clinical condition. Generally, larger high-quality trials have tended to show little or no significant effects, as was concluded by the authors of the second Lancet study cited above (“There is increasing evidence that more rigorous trials tend to yield less optimistic results than trials with less precautions against bias.” Homeopaths respond that most of the larger high-quality trials tested a single homeopathic medicine, without the individualization of treatment common to homeopathic treatment.

This does not explain why small trials should have more strongly positive outcomes than large trials. However, this is a feature of trials of conventional medicine also – and is generally attributed to "publication bias" – the tendency of trials to be reported only if the outcome is clearly positive; many small trials with negative or inconclusive outcomes go unreported because they are thought to be uninteresting.

In 1999, the Government of Switzerland, for 5 years, allowed health costs for treatment with homeopathy and four other CAM modalities to be reimbursed under the country’s health insurance scheme, and set out to evaluate their cost-effectiveness (the Complementary Medicine Evaluation Programme (Programm Evaluation Komplementärmedizin, PEK). A team of scientists and practitioners, including a homeopath, conducted a meta-analysis that became the single most cited study of homeopathy, arousing considerable media attention and a storm of protest from homeopaths. The study, which was published in the Lancet (by Shang et al.) adopted a novel approach; whereas traditional meta-analyses have tried to combine all studies of a given condition, this was a "global" meta-analysis testing the hypothesis that all effects of homeopathic remedies are placebo effects. If so, the authors reasoned, then the predominance of positive reports reflect publication bias, and hence the magnitude of effects should diminish with sample size and study quality, and for the largest and best studies there should be no effect.

They analyzed 110 placebo-controlled homoeopathy trials and 110 matched conventional-medicine trials. Overall, the conventional trials showed some real effect, in that some effect was still present in the largest and best trials, but the trials of homeopathy did not. The authors concluded that their analysis was consistent with homeopathy being no better than placebo, and suggested that no further research on homeopathy is necessary. The article was accompanied by an unsigned editorial titled “The end of homeopathy”" and another, signed, editorial . The Lancet subsequently published a selection of critical correspondence, and received an open letter from the Swiss Association of Homoeopathic Physicians (SVHA). which declared:

“The meta-analysis may be statistically correct. But its validity and practical significance can be seen at a glance: not one single qualified homoeopath would ever treat one single patient in clinical practice as presented in any of the 110 analysed trials! The study cannot give the slightest evidence against homoeopathy because it does not measure real individual (classical) homoeopathy. It confounds real homoeopathic practice with distorted study forms violating even basic homeopathic rules.”

In the Shang et al. review, 21 homeopathic trials were judged of “high quality”; these, overall, showed a benefit of homeopathic treatment. In the final analysis, the researchers included only the largest of these studies; the 8 largest trials showed that homeopathic treatment was comparable with a placebo, while 6 similarly large conventional trials were not compatible with a placebo effect. Of the 8 largest and best homeopathic trials, only one used an individualized approach to treatment, the other seven used a single remedy prescribed to homeopathic treated subjects. Such non-individualized treatment is common in the larger clinical trials (one of the trials even tested a rarely used homeopathic medicine, Thyroidinum, in the treatment of weight-loss, in a previously untested treatment protocol).

Critics of the Shang et al. analysis questioned how definitive it is, noting that it involved subjective judgements of study quality. Several studies defined as "high quality" by Linde et al. (1997) were not defined by high quality by Shang et al. most of which showed a positive effect of homeopathic treatment.The Shang et al. analysis also excluded a relatively large study of chronic polyarthritis (N=176) by Wiesenauer because no matching trial could be found. The authors of an article in the Journal of Clinical Epidemiology say "This result can be interpreted differently. Following Shang's perspective it can be explained by small study bias (which includes publication bias). In contrast, one may hypothesize that Shang's result is falsely negative." The authors noted that four of the 21 best trials selected by Shang et al. dealt with preventing or treating muscle soreness—these consistently found no benefits to homeopathy, so if it is accepted that homeopathy is not useful in this condition, the remaining 17 trials show an overall significant effect, mainly determined by two trials on influenza-like diseases. Thus they argue that it is still possible that homeopathy might be effective for some conditions and not for others.

Proponents of homeopathy also note that some of the conventional studies analysed by Shang et al. may have shown a treatment effect but that some of these treatments have since been withdrawn because of side effects. Critics of homeopathy agree—they say that in conventional medicine, treatments are abandoned when trials show them to be ineffective or unsafe, or when a better drug is found; by contrast, no homeopathic treatment has ever been withdrawn after a trial showed it to be ineffective. Homeopaths contend that flawed trials cannot be used to show that homeopathic treatment is ineffective.

Safety

The highest ideal of cure is the speedy, gentle, and enduring restoration of health by the most trustworthy and least harmful way (Samuel Hahnemann)

The U.S. Food and Drug Administration's view of homeopathy is that there is no real concern about the safety of homeopathic remedies because of the extremely small dosages. The F.D.A. has deemed that the vast majority of remedies are over-the-counter drugs that do not need a doctor's prescription and that are safe enough for home care. In the U.S.A., homeopathic remedies must have at least one indication for usage for a disease or condition that is self-limiting and that does not require medical diagnosis or medical monitoring. The European Union allows homeopathic medicinal products, if they are at least 3X, that is, they may not contain either more than one part per 10,000 of the mother tincture or more than 1/100th of the smallest dose of an active substance. No specific therapeutic indication may be given on the label of the product. Some physicians, however, maintain that homeopathic treatment is relatively unsafe, because it might delay other treatment/s, if it fails to work. Homeopaths respond by claiming that using homeopathic remedies can delay or reduce the use of conventional medicines that are ineffective and dangerous.

Probably every modern pharmacologist would agree with Hahnemann that the drugs prescribed by conventional physicians in the 19th century were at best ineffective and often dangerous. However, some homeopaths question whether even modern medical drugs are safe and effective, and recommend homeopathic remedies instead. For example, a 2006 survey by the U.K. charitable trust Sense About Science revealed that homeopaths were advising travelers against taking conventional anti-malarial drugs, instead recommending they take a homeopathic remedy. Even the director of the the Royal London Homeopathic Hospital condemned this:

I'm very angry about it because people are going to get malaria - there is absolutely no reason to think that homeopathy works to prevent malaria and you won't find that in any textbook or journal of homeopathy so people will get malaria, people may even die of malaria if they follow this advice.

Another concern of physicians is that some homeopaths discourage the use of vaccines. Many homeopaths think that vaccination for common diseases, such as measles and chicken-pox, is unnecessary, and some believe that vaccines can be damaging to health, because of the mercury and aluminum in them, because the bacterium or virus in the vaccine may neither be dead nor weak enough, and/or because some childhood infectious diseases may strengthen immune responsiveness. Such advice is considered irresponsible by many public health professionals, who assess the benefits of vaccination as vastly outweighing the risks.

Measles is not a major killer in the western world, where most children are vaccinated at about two years old. However, in 1999 there were 875,000 deaths from measles worldwide, mostly in Africa. In 2001, a "Measles Initiative" was initiated involving the American Red Cross, UNICEF and the World Health Organization, By 2005 more than 360 million children had been vaccinated, and the death toll had dropped to 345,000.

Adult herpes zoster infection is a reactivation of childhood chickenpox, affects 1 in 3 adults, and can cause chronic, severe nerve pain ("postherpetic neuralgia"} in 10-18% of cases, and eye involvement in 10-25%. Chickenpox immunization prevents this; a herpes zoster vaccine is now recommended for all adults 60 years and older.

Government and institutional assessments

In the United Kingdom, the House of Commons Science and Technology Committee produced a report in 2010 that evaluates the evidence for homeopathy with reference to its use in Britain's National Health Service. It concluded that the principle of "like-cures-like" is "theoretically weak" and it "fails to provide a credible physiological mode of action for homeopathic products. We note that this is the settled view of medical science." The report also expresses considerable doubt as to the effectiveness of ultra-dilution in homeopathy and describes it as "scientifically implausible". It found that there was no good evidence of effectiveness of homeopathy:

In our view, the systematic reviews and meta-analyses conclusively demonstrate that homeopathic products perform no better than placebos.

The report rejected evidence presented by the British Homeopathic Association on systematic reviews and accepted Professor Edzard Ernst's account of the failings in the systematic reviews and other evidence presented by the BHA. It stated that advocates of homeopathy had chosen "to rely on, and promulgate selective approaches to the evidence base". It also rejected calls for further research:

There has been enough testing of homeopathy and plenty of evidence showing that it is not efficacious. Competition for research funding is fierce and we cannot see how further research on the efficacy of homeopathy is justified in the face of competing priorities.

It recommended against the use of homeopathy on the NHS because of the ethical problems in prescribing a placebo (as they concluded homeopathy to be): in particular, for a placebo to be effective, the patient must not know it is a placebo, but medical ethics requires that a patient must be able to make an informed choice. It also advised that, if the NHS appears to endorse homeopathy, there is a danger that patients will neglect conventional medicine, with potentially serious health consequences. The report concludes that homeopathy should not be funded by the NHS, that funding of homeopathic hospitals should not continue and that NHS doctors should not refer patients to homeopaths.

The report conclusions have been supported by the British Medical Association. The Royal Pharmaceutical Society of Great Britain suggested that patients ought to be "made aware of the fact that there is no scientific basis for the use of homeopathy", and that unless homeopathy can be shown to be efficacious "using appropriate methodology (as for conventional medicines)" any "claims of efficacy should be removed from the label". It also concluded that "homeopathic remedies should be reviewed by NICE if they are to be used within the NHS to ensure that they give value for money" – historically, homeopathy has not been subject to review by NICE. The British Government has decided to continue funding homeopathy (at a very low level) on the NHS.