Homeopathy/Draft

Homeopathy or homoeopathy is a system of alternative medicine. The term derives from the Greek hómoios (similar) and páthos (suffering). Homeopathy is based on "the principle of similars", which asserts that substances known to cause particular symptoms can also, in low and specially prepared doses, help to cure diseases that cause similar symptoms. Although homeopathy is practiced by some medical doctors, as well as other health professionals and consumers in virtually every country in the world, homeopathy is not accepted by most mainstream medical doctors or conventional scientists today.

Some principles of homeopathy have been utilized in various forms for thousands of years, but its basic principles 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. In homeopathic theory, every person has a "vital force", with the power to promote healing and/or maintain good health (the term "vital force" is akin to qi in traditional Chinese medicine). In this theory, the symptoms of a disease reflect efforts of the vital force to counter infection, or to resist damage from environmental toxins or from various stresses. Homeopathic treatment attempts to strengthen this "vital force" with the help of remedies, which are extremely small doses of drugs diluted in water or ethanol and dispensed in pills or liquid form. Remedies are chosen for their ability (in large doses) to provoke the very symptoms that the remedy is intended to heal (and thereby for their presumed ability to stimulate natural healing). Homeopaths believe that this "vital force" is akin to what physiologists would call the body's "defense systems".

"Classical homeopathy" refers to the original principles in which individual remedies are chosen according to the physical, emotional, and mental symptoms that the sick person 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, generally chosen for their ability (in large doses) to produce symptoms of a specific disease.

The basics of homeopathy
The underlying concept of homeopathy is "like cures like"—a principle described by Hippocrates more than 2,000 years ago that has been used in various medical systems since then in many diverse cultures. "Like cures like", the "Law of similars", and related maxims are common in anthropological literature.

Historical origins
The early Greek physician Hippocrates of Cos (c. 450 BCE - 380 BCE) was a prolific medical historian who is considered to be the "father of medicine". He wrote about many healing practices, one of which relied upon the use of similars, that is, the use of "like to cure like." In the 15th century, the alchemist, physician and astrologer Paracelsus asserted the healing power of "signatures," that is, whatever a substance in nature looked like by its color and its shape, represented the types of diseases for which it was effective in treating. This led him, for example, to teach that the pricking of thistles cures internal inflammation, and is sometimes cited as an early form of the "principle of similars". But it was not until the late 18th century and early 19th century when German physician, Christian Friedrich Samuel Hahnemann (1755-1843) developed the experimental method of "provings" (studies in human toxicology) that provided greater specificity and detail to determining what a substance causes. While translating into German the Treatise on Materia Medica (1789) by the Edinburgh physician William Cullen, Hahnemann described that a specific medicine, Cinchona officinalis (Peruvian bark, a medicinal substance that contains quinine) causes symptoms similar to malaria, which he then asserted was the reason that Peruvian bark and quinine was effective in treating this disease.

After 1783, disillusioned with the medicine of the time and the many toxic effects of its treatments, Hahnemann gave up his medical practice and devoted himself to translating medical books (he spoke nine languages). In his lifetime, Hahnemann translated more than 9,000 pages, including many of the leading medical and chemistry textbooks of the day. In one of these, William Cullen, the best known physician of his time, had written that cinchona bark (which contains quinine) was effective in the treatment of malaria because of its bitter and astringent properties. Hahnemann questioned these assertions because he knew that other substances were as bitter and astringent, but had no therapeutic value in this deadly disease.

Being an avid experimenter, Hahnemann took cinchona bark himself and saw that the symptoms that it caused were similar to the symptoms of the diseases for which it was prescribed. Hahnemann then experimented with other substances and found that the symptoms that they caused were also similar to the symptoms of the diseases for which they were prescribed. These experiments led him to formulate the "Principle of Similars", expressed by him as similia similibus curentur or "let likes cure likes". He used this principle to develop a new system of health care, which, instead of the often toxic and ineffective drugs offered by conventional physicians, employed more gentle alternatives at low doses. He believed that diseases were caused by "spirit-like derangements of the spirit-like power that animates the human body", and that effective healing called for medicines that would stimulate this vital force.

Hahnemann named his system of health care "homeopathy" (meaning "like disease") and coined the term "allopathy" ("different than disease") to refer to the conventional medicine of the day, because its drugs were sometimes "similar," sometimes "opposite," but usually simply "different" to the symptoms of the sick person. .

For the first two decades of Hahnemann's use of the principle of similars, he used crude doses or just slightly potential doses of various medicinal substances. Hahnemann 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. To his surprise, it seemed that reducing the dose did not diminish the effectiveness of his treatments. Indeed, he concluded that his remedies worked better and better the more he diluted them as long as he “potentized” them between each stage of dilution by vigorous shaking (succussion). Homeopathy became inextricably linked with this process of ultradilution – dilution of substances by succussion. Although Hahnemann was an avid experimenter, he did not offer a specific model as to how or why these potentized medicines might have therapeutic benefits. The full formulation of the molecular concentration 'law', however, did not come until 1865, well after Hahnemann's work.

Homeopathy was introduced into the U.S.A. in 1825 by Hans Burch Gram, a Boston-born doctor who had studied homeopathy in Europe. In 1830, the first homeopathic schools opened (the first homeopathic medical college in the U.S.A. opened in 1835, in Allentown, Pennsylvania), and throughout the 19th century dozens of homeopathic institutions appeared in Europe and the U.S.A. Apart from his ventures into homeopathy, Hahnemann had been a prominent and respected public health reformer, and the Medical Society of the Country of New York had given him honorary membership. However, a few years later the society rescinded this when they realized the "ideological and financial threat" that homeopathic medicine 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 all American medical practitioners were homeopaths, and there were 20 homeopathic medical colleges (including Boston University, New York Medical College, University of Michigan, University of Minnesota, Ohio State University, and University of Iowa) and more than 100 homeopathic hospitals in the U.S.A. One reason for the growing popularity of homeopathy was its relative success in treating people suffering from the infectious disease epidemics that raged at the time. Cholera, scarlet fever, typhoid fever, and yellow fever were rampant and killed many people. But death rates in homeopathic hospitals were often much lower than in the conventional hospitals (the death rates in conventional medical hospitals were typically between two to eight times higher by percent of patients with these infectious diseases compared with those in homeopathic hospitals), whose cures – purging, blood-letting and mercury treatments, were often worse than the diseases themselves, and did nothing to combat them.

However, in the early 20th century, the "Flexner Report," sponsored by the Carnegie Foundation with significant support from the American Medical Association, triggered major changes in American medical education. As a result, most homeopathic medical schools were closed down, while others converted to become conventional medical schools (including 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.

Homeopathic "provings"
Homeopathic practitioners derive their remedies from provings, in which volunteers are given substances (usually in single-blind or double-blind trials), the effects of which are recorded in textbooks, called Materia Medica and Repertory, or nowadays in expert system software. Homeopathic provings provide an experimental 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 subsequently used to compare with a patient's physical and psychological symptoms in order to select, as the appropriate remedy, the substance whose effects are closest to the patient's symptoms—the "similimum".

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, although having never been listed in the HPUS puts the homeopathic drug in a different standard of regulation than conventional drugs and medical devices. A summary describes the principles: FDA regulates homeopathic drugs in several significantly different ways from other drugs. The Manufacturers of homeopathic drugs are deferred from submitting new drug applications to FDA. 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 Senator Royal Copeland, a homeopathic physician, gave the FDA the power to regulate drugs, and gave 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; simple listing in a reference is not sufficient. Today, homeopaths use about 3,000 different remedies, from animal, plant, mineral, or synthetic sources.

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, pharmacologic designation or biological nomenclature, is preferred, such as Natrum muriaticum rather than sodium chloride. Most remedies used in homeopathy are derived from flowering plants, but some conifers and ferns are used, as well as fungi, including lichens, and brown and red algae. Other remedies are derived from the mineral and animal kingdoms.

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 some 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 (over-the-counter).

Preparation of homeopathic remedies
The most characteristic &mdash; and controversial &mdash; principle of homeopathy is that the efficacy of a remedy can be enhanced and its side-effects reduced by a process known as 'dynamization' or 'potentization', whereby liquids are diluted (with water or ethanol) and shaken by ten hard strikes against an elastic body ('succussion'), to get the next, succeeding 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 serial dilutions by Hahnemann used a 1 part in 100 (centesimal; $$'C'$$ potencies), or 1 part in 50,000 ( Quintamillesimal; $$'LM' or  'L'$$ potencies). James Tyler Kent 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). The number of molecules in a given weight of a substance can be calculated by Avogadro's number (see below), and it is extremely unlikely that even one molecule of the original substance would still be present in a $$30C$$ dilution. Thus, homeopathic remedies of a high 'potency' contain just water, but water that, according to homeopaths, retains some essential property of one of the substances that it has contacted in the past.

Similia similibus curentur : the law of similars
Similia similibus curentur or 'let likes cure likes', is the assertion that a disease/problem can be cured by remedies that (in macroscopic, milligram doses) produce the same symptoms as those of the disease. This assertion, known as "the law of similars", is a guiding principle in homeopathy.

Homeopaths consider that two conventional concepts, vaccination, and hormesis, can be considered as analagous to homeopathy's law of similars and the use of small doses.

Vaccination
Emil Adolph von Behring (1854-1917), who won the first 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 principle 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 active ingedients, there are important differences. First, the doses used in homeopathic remedies are always very much lower than used in vaccines. Second, vaccines produce a measurable immune response (e.g., immunoglobulin production). Homeopathic remedies do not routinely produce a measurable immune response.

Thus conventional treatments involve application of measurable doses of substances, at levels known to activate mechanisms of cellular response. In contrast, homeopathic preparations above the $$24X$$ ($$12C$$) potencies do not contain enough molecules to activate any known metabolic or signalling pathway.

Mithridatization and hormesis
Mithridatization (which is not a term used in contemporary science or medicine) may be a better metaphor than vaccination, for homeopathic treatment. Mithridatization is the chronic administration of subtoxic doses of a toxin, in an attempt to develop resistance (or "tolerance") to large doses of the toxin. It is alleged that Mithridates VI, King of Pontus (132-63 BC) used this technique to protect himself from his enemies.

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 indeed become tolerant to them. A beekeeper, however, may become hypersensitive to the venom and, after receiving a sting, go into anaphylaxis. This type of response to small, not necessarily precisely measured, doses is not predictable on an individual basis. 'Allergic desensitization' is a technique 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 (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.

Both mithridatization and homeopathy might be considered as instances of hormesis, which describes the phenomenon that some chemicals at high concentrations have opposite biological effects to those at low concentrations.

Professional homeopaths: who are they?
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 certify "professional homeopaths" who have attended homeopathic schools and who then pass independent examinations that grant "certification" as homeopaths. In the U.S.A., MDs and DOs are eligible for this certification. 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).

In Europe, homeopathy is practiced by many conventional physicians, including 30-40% of French doctors and 20% of German doctors. Some homeopathic treatment is covered by some European public health services, including in France and Denmark. In the U.K., five homeopathic hospitals are funded by the NHS and homeopathic remedies are sold over the counter, and there, homeopathy is one of the most popular alternative and complementary treatment modalities. Two countries which formerly offered homeopathy under their public health services no longer do so: from 2004, homeopathic remedies, with some exceptions, were no longer covered by the German public health service, and in 2005, the Swiss Government withdrew homeopathy and four other complementary treatments, stating that they did not meet efficacy and cost-effectiveness criteria.

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.

In India, homeopathy is formally recognised by the Government as one of the Indian 'National Systems of Medicine', under the Department of AYUSH (Ayurveda, Yoga & 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.

A typical homeopathic visit
Homeopathic remedies can be prescribed by pure homeopaths, naturopaths, acupuncturists, chiropractors, and mainstream physicians with additional homeopathic training and certification, and how these decide what remedies to prescribe will differ accordingly. Classical homeopaths place emphasis on the patient's symptoms as well as the person's psychological state, and they gather this information from an interview with the patient, typically lasting from 15 minutes to two hours, with one or more follow-up consultations of five to 45 minutes. They place more emphasis on the way the patient experiences their disease rather than diagnosing the disease - i.e. they give priority to the syndrome of symptoms rather than to the results of conventional medical tests alone. A diagnosis will also be used to rule out treatment with unnecessary remedies. This differs strongly from the conventional medical approach, which is to try to identify the causes of the disease.

When considering the person's symptoms, some categories of change are identified as important: "(1) emotions; (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; and (19) recall of past experiences."

After the interview, the homeopath consults the references described above". Some homeopaths make quick prescriptions based on "keynotes" -the highlights of the best known characteristics of a remedy, but the real challenge of homeopathic practice is to find the remedy that best matches the patient's symptoms - the "similimum". A fundamental reasons for conflict between conventional medicine and homeopathy is that homeopathy rejects the concept of treatments that target common mechanisms of disease, but seeks individualised treatment.
 * A physician qualified in both homeopathy and conventional medicine, after diagnosing a chronic condition that does not have consistently effective conventional treatments, may prescribe a homeopathic remedy which he feels may be more effective and is likely to have fewer side effects than conventional drugs.
 * Homeopaths recognize that trauma can be a surgical emergency, but may use homeopathic remedies adjunctively.
 * Homeopaths disagree with conventional medicine about the role of immunization and chemoprophylaxis for infectious diseases.
 * Homeopathic practitioners prescribe remedies for many conditions. For some conditions, like asthma and acute bronchitis, homeopathic remedies are often prescribed not only to alleviate chronic symptoms, but also to treat acute attacks. Homeopathic remedies might also be used after an asthmatic episode with the intent to prevent recurrences.
 * An adequately trained homeopath is expected to recognize symptoms that indicate an acute and potentially fatal condition. The practitioner is expected to have emergency medical training and equipment appropriate to his or her level of medical training in the place of practice (e.g., dressings and basic airway management tools for an individual with training at the Emergency Medical Technician (EMT) of Basic or higher level, and preferably an automatic external defibrillator and advanced cardiac life support resources generally accepted as appropriate for an office. Potentially serious acute ailments may require medical supervision, but homeopaths sometimes prescribe remedies either for adjunctive use or as alternatives to conventional treatment.

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

The Claims for homeopathy
Homeopaths view illness as a "holistic disturbance in the homeostasis of the total being" and accordingly, are willing to offer treatment to almost any patient, regardless of their underlying disease. "The physician must remember that he is treating a patient who has some disorder; he is not prescribing for a disease entity." .

Homeopathic doctors claim that their remedies are useful for a wide range of minor ailments, from cuts and bruises to coughs and colds. Patients often come to homeopaths with long-term problems which have not responded to conventional medicine, and homeopaths are willing to offer remedies for these conditions; thus they often treat patients with conditions such as eczema, chronic fatigue syndrome, asthma, migraine, irritable bowel syndrome, allergy, arthritis, fibromyalgia, hypertension, crohn's disease, premenstrual syndrome, chronic rhinitis, anxiety and depression, and dental conditions including abscess, gum swelling, reversible pulpitis, toothache with decay, and pericoronitis. They also treat patients with the most serious diseases, including mutiple sclerosis, cancer and AIDS

Homeopaths claim that there is objective evidence that some of their treatments are beneficial (see Tests of the efficacy of homeopathy). .

Conflict with conventional medicine
The theory underlying homeopathy is not considered to be plausible by most scientists working in academic institutions in Europe and the U.S.A., and in key respects, the treatment advice offered by homeopaths is in disagreement with conventional medicine. The conventional view is that homeopathic treatments, insofar as they have any effect at all, exploit the placebo effect - i.e. that the only benefits are those induced by the power of suggestion, by arousing hope, and by alleviating anxiety. Conventional medical opinion does not deny the efficacy of placebo treatments in many cases, and placebos have played a large part in conventional medicine since their first deliberate use by William Cullen in the 18th century. Modern physicians, however, are constrained by ethical codes of practice that forbid them from deliberately misleading their patients; rather than prescribing placebos themselves, some therefore prefer to refer patients to regulated practitioners of alternative medicine.

There is however concern among conventional medical practitioners that some patients may seek homeopathic treatment as a first resort, even for conditions where there are effective conventional treatments. For example, asthma and other respiratory disorders with a seemingly mild initial presentation can be a life-threatening condition, and acute attacks, if not treated effectively, can lead to sudden death. According to conventional opinion, prescribing homeopathic remedies in these cases may delay the delivery of effective conventional treatment, with potentially serious consequences. Medical organisations advise that there is no evidence that homeopathic remedies are effective in these circumstances, and recommend that they should only ever be used in conjunction with conventional treatment.

Homeopaths also assert that corticosteroids are immunosuppressant drugs that may provide temporary relief of asthma symptoms but may lead to more serious chronic disease and to increased chances of death. Medical opinion is that this assertion is uninformed scare-mongering. The medical use of corticosteroids is not for symptom relief but to prevent inflammation that itself can have serious consequences. Inhaled corticosteroids, which do not spread through the body and cause widespread effects, but stay on the breathing passages and prevent inflammation, are medically preferred to systemic corticosteroid therapy.

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 seek to avoid conventional treatments that suppress symptoms. Mainstream physicians accept that some disease is indeed a disturbance in normal function, whether due to external, genetic, or internal reasons. However, they consider that most disease can be attributed to 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), all of which homeopaths consider to be co-factors to disease, not causes of them. Conventional physicians often use drugs simply to suppress the symptoms of a disease (to alleviate the pain, injury, and distress that they cause). However, the main goal of medical treatment is to eliminate the causes of the disease with the help of 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. Although the AMA did not enforce many of its ethical guidelines, the "consultation clause" was one of the few that it did. 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. ".

Conflict on individualization
Another area of conflict is the insistence that only homeopaths provide remedies tailored to the individual. Classical homeopathy frowns on the use of multiple concurrent remedies; a major repertory contained approximately 3,000 remedies, presumably used singly. In comparison, the The U.S. Food and Drug Administration Approved Drug Products with Therapeutic Equivalence Evaluations 26th Edition Electronic Orange Book (EOB)4 lists 11,706 approved prescription drugs (RX) with therapeutic equivalence evaluations, [and] 390 approved over-the-counter (OTC) drugs. They contain 1323 chemically distinct ingredients in measurable quantities, not infrequently used in combination.

As an indication that medicine constantly reevaluates and rejects things with undue risk and inadequate benefit, the Orange book also contains 8820 approved products that have been discontinued.

As far as defining individualized remedies, the field of pharmacogenetics individualizes, but based on reproducible criteria from the patient's genome. A 2007 study created a network of connections of FDA approved drugs and their active ingredients with known human gene targets. This resulted in 1052 drugs targeting 485 proteins, the proteins identifiable from genomic data rather than subjective assessments of symptoms.

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.

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 indeed effective. This conflicts with an approach that believes that treatments must be individually tailored to each patient. In reality, some homeopathic trials do use some standardization, but not always to an extent which would make the trials statistically robust.

Scientific basis of homeopathy
See articles on solitons, clathrates, nanobubbles and The memory of water.

Homeopathy was developed at a time when many of the 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. Although the hypothesis of atoms can be traced back to the ancient Greeks, their size was not calculated until 1865 (by Josef Loschmidt).

We now know that, for example, a teaspoon of seawater (5 ml) contains about 160 mg of NaCl. The molecular weight of NaCl is 58.4, so by Avogadro's number, (or, in German-speaking countries, Loschmidt's number), 58.4 g of NaCl (one mole) contains 6.02×1023 molecules. We can thus calculate that our teaspoon contains about 2×1021 molecules of NaCl. A 12C dilution of seawater will have about one molecule of NaCl per litre.

Thus homeopathic 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 essential healing power of their preparations is not to be found in the chemical action of molecules, but perhaps in the arrangement of the water molecules, giving rise to the expression 'the memory of water'.

Water is not simply a collection of molecules of H2O, it contains several molecular species including ortho and para water molecules, and water molecules with different isotopic compositions such as HDO and H218O. In addition, even double-distilled and deionized water always contains trace amounts of contaminating ions. There is some support for the notion that water can have properties that depend on how it has previously been processed (i.e. that water has, in some sense, a kind of "memory"). The evidence indicates that the "memory" is due primarily to solute and surface changes occurring during this processing. In particular, water, as a result of repeated vigorous shaking, might include redox molecules produced from water, dissolved atmospheric gases and airborne contaminants, silicates - tiny glass "chips", nanobubbles and their material surfaces, dissolved ions, including from the glassware, apart from the original medicinal substance it was diluting. It is theorized that each substance that is placed in the double-distilled water will interact with the silicate fragments in differing ways, thereby changing the structure of the water. There might also be some effects of successive shaking on water structure - "clustering" of water molecules.

These mechanisms are not mechanisms of memory in any cognitive sense; the term memory here is used as a metaphor, implying only that the past history has a discernible influence on the present properties, but homeopaths believe that, through these or other mechanisms, water can form and retain some "memory" of the original medicinal substance. Many homeopathic remedies are however available as solid preparations -"pillules" of lactose and/or sucrose, intended as inert cores which are transformed into homeopathic drugs by impregnating them with a dilution of homeopathic stock

In brief, for homeopathy to receive serious scientific consideration, there needs to be plausible explanations for the following:
 * how the process of manufacturing a homeopathic remedy could yield a biologically active substance or solution
 * 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

and


 * clear and irrefutable evidence for the effectiveness of homeopathic remedies, evidence that cannot be explained in conventional terms.

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

Some materials scientists, physicists, and other scientists have investigated how homeopathic medicines might work including some reports of the alteration of water by homeopathic preparations, but there are no generally accepted theories about how these occur or about how those altered properties would affect biological systems.

Tests of the efficacy of homeopathic remedies
Some studies of homeopathy have been funded by the U.S. National Center for Complementary and Alternative Medicine (NCCAM). In NCCAM's taxonomy of complementary and alternative medicine, homeopathy is a "whole system" that is an alternative to the entire medical mode, although it can be complementary to conventional care. The funded studies include:


 * A study on fibromyalgia, which showed clinical benefits from individually chosen homeopathic remedies as well as objective differences in EEG readings in homeopathic and placebo subjects.


 * A study on homeopathy for mild traumatic brain injury. This pilot study indicate a significant benefit from the homeopathic treatment but requires large-scale, independent replication.

Cochrane Reviews did a meta-analysis of seven randomized controlled trials, three prevention trials (number of participants, $$N = 2265$$) and four treatment trials, $$(N = 1194)$$. The authors considered only two were statistically adequate, but data from the prevention trials showed no effect. Data from the treatment trials showed enough efficacy that further trials were recommended, but that the remedy could not be recommended for first-line therapy. Homeopaths often consider large trials invalid because they do not reflect the individualized nature of homeopathic treatment.

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 most homeopathic products because of the extremely small dosages. The F.D.A. has deemed that the vast majority of homeopathic medicines are over-the-counter drugs (OTC), that is, 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&thinsp;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 effective, conventional medical treatment.

Probably every modern pharmacologist would agree with Hahnemann that the drugs prescribed by conventional physicians of 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 is that some homeopaths discourage the use of vaccines. Many homeopaths think that vaccination for common diseases, such as measles and chicken-pox, is unneccessary, and some believe that vaccines can even be damaging to health, in part because of the mercury and aluminum in them, in part because the bacterium or virus in the vaccine may neither be dead nor weak enough, and in part because some childhood infectious diseases may strengthen immune responsiveness. Such advice is generally considered irresponsible by public health professionals. 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 [[neuralgia|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. Childhood immunization against chickenpox prevents herpes zoster.