Homeopathy

• 1. Introduction

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  Homeopathy was conceived in 1796 by the German physician Samuel Hahnemann, and it is now classed as a pseudoscientific system of alternative medicine. Its remedies are made by diluting a chosen substance again and again. The final product often cannot be told apart from the plain water, sugar or alcohol used to dilute it. Often not even one molecule of the original substance can be expected to remain.

  Practitioners nonetheless say that such preparations, taken by mouth, can treat or cure disease. The scientific and medical communities have gone further than doubt. They have described the practice as quackery and fraud.

  How did a physician come to build a medicine around ever-weaker doses? Why did patients in the 19th century often fare better with homeopaths than with the doctors of their day? And why are governments now withdrawing public money from a practice that once filled dozens of institutions across Europe and the United States?

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• 2. The Bark Experiment

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  Hahnemann was translating a medical treatise by the Scottish physician and chemist William Cullen into German when his doubts began. Cullen claimed that cinchona bark cured malaria because it was bitter. Hahnemann was sceptical, so he swallowed some bark to see what would happen. He developed fever, shivering and joint pain, symptoms like those of malaria itself. From this he concluded that every effective drug causes, in healthy people, symptoms similar to those of the disease it treats.

  He summed up the idea in Latin as similia similibus curentur, or "like cures like". The name homeopathy comes from the Greek hómoios, meaning like, and páthos, meaning suffering. The word first appeared in print in 1807. Hahnemann also coined the expression "allopathic medicine", which was used pejoratively for traditional Western medicine. He had rejected the mainstream medicine of his day as irrational, because it was largely ineffective and often harmful. He favoured single drugs at lower doses, and he promoted an immaterial, vitalistic view of how living organisms function.

  The bark story does not survive testing. In 1861 Oliver Wendell Holmes noted an account of eating cinchona bark that failed to reproduce the symptoms Hahnemann reported. Later science showed that cinchona cures malaria because it contains quinine, which kills the Plasmodium falciparum parasite. That mechanism is unrelated to Hahnemann's ideas, and his law of similars remains unproven.

  Hahnemann next set out to learn what many other substances do to the human body. The procedure became known as homeopathic proving. The first recorded provings appeared in his 1796 Essay on a New Principle. His Fragmenta de Viribus, from 1805, reported 27 provings, and his Materia Medica Pura, from 1810, reported 65.

  Volunteers were often observed for months at a time. They kept extensive journals of their symptoms at set times of day. They were forbidden coffee, tea, spices and wine. Chess was banned too, because Hahnemann considered it too exciting. Beer was allowed, and moderate exercise was encouraged. By the time of James Tyler Kent's Lectures on Homoeopathic Materia Medica in 1905, 217 preparations had undergone provings.

  Defenders say provings helped shape the clinical trial, through early simple control groups, systematic quantitative procedures and some of the first uses of statistics in medicine. Records of homeopathic self-experimentation even hinted that nitroglycerin might help angina, although homeopaths never used it that way at the time. Yet provings differ fundamentally from clinical trials. They are subjective and not blinded. As early as 1842, Holmes had noted that they were impossibly vague and that the supposed effects could not be repeated among different subjects.

  Hahnemann gathered his whole system in The Organon of the Healing Art, published in 1810. Homeopaths still use its sixth edition, which appeared in 1921. He believed large doses of drugs that caused similar symptoms would only aggravate illness, and that fear drove him toward extreme dilution.

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• 3. Dilution Arithmetic

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  A 2C dilution holds one part of the original substance in 10,000 parts of solution, a concentration of 0.01%. That is the gentlest step on a ladder that climbs far beyond anything chemistry can detect. Hahnemann created the centesimal or "C" scale, which dilutes a substance by a factor of 100 at each stage. He favoured it for most of his life. A decimal scale, written "X" or "D", dilutes by a factor of 10 at each stage. In his last ten years he also developed a quintamillesimal "Q" scale, which diluted the drug to 1 part in 50,000.

  By 6C the original substance has been diluted to one part in a trillion. The greatest dilution reasonably likely to contain even one molecule of the original substance is about 12C, or 1 part in 10 to the power of 24. This limit is tied to the Avogadro number. Hahnemann advocated dilutions of 1 part to 10 to the power of 60, which is 30C. Even so, he remarked that "there must be a limit to the matter".

  The methods vary. Serial dilution adds solvent to part of the previous mixture. The "Korsakovian" method, marked K on a label, empties the vessel and refills it with solvent, treating the fluid clinging to the walls as enough for the new batch. Fluxion passes water continuously through the vial. Insoluble solids such as granite, diamond and platinum are ground with lactose in a step called trituration.

  Hahnemann held that more dilute meant more potent. To counter the weakening he formed the view that vigorous striking on an elastic surface was necessary, a process called succussion. Homeopaths cannot agree on how many strikes or how much force are needed. There is no way to test the claimed results.

  Critics reach for analogies to show the scale. A 12C solution is equivalent to a pinch of salt in both the North and South Atlantic Oceans. One-third of a drop of a substance mixed into all the water on Earth would give roughly 13C. The science channel Kurzgesagt calculated that a 30C pill containing a single atom of the target substance would have to stretch from the Earth to the Sun, and would collapse into a black hole under its own gravity. Robert L. Park noted that a 200C dilution of duck liver, sold as Oscillococcinum, would need 10 to the power of 320 universes' worth of molecules to hold one original molecule.

  Modern advocates answer with "water memory", the idea that water remembers substances once mixed in it. It has never been shown to have any detectable effect. Any water has touched millions of substances in its history, and homeopaths cannot explain why the chosen one is singled out. Some point to hormesis, but outside that narrow zone the effect of a dose declines with dilution as normal.

  The 10:23 campaign and James Randi staged a blunt test of the claims. Hundreds of demonstrators in the United Kingdom, Australia, New Zealand, Canada and the United States took large "overdoses". None was injured, and, in the campaigners' words, "no one was cured of anything, either".

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• 4. Miasms and Remedies

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  Hahnemann's theory of chronic disease rested on what he called miasms, described as "infectious principles" and as "peculiar morbid derangements of vital force". He first named three: psora, the itch; syphilis; and sycosis, the fig-wart disease. Psora mattered most. He tied it to itching skin diseases and blamed it for a startling list that included epilepsy, cancer, jaundice, deafness and cataracts. Later homeopaths proposed more miasms, including ones for tuberculosis and cancer.

  The idea holds that suppressing a skin symptom with medicine drives the cause deeper, until it appears in the internal organs. Critics argue that miasms were devised to protect the system from treatment failures. The theory also cannot cover hundreds of sorts of disease, or explain genetics, environment and each patient's own history. It remains disputed even within homeopathy.

  Choosing a remedy begins with a consultation, which may last 10-15 minutes or well over an hour. The patient describes their medical history and their "modalities", meaning whether symptoms shift with the weather and other outside factors. The homeopath also asks about mood, likes and dislikes, and life circumstances. This "symptom picture" is matched against a "drug picture" in a reference book. In classical homeopathy, the aim is a single preparation matching the totality of symptoms. "Clinical homeopathy" combines several preparations according to the illness.

  Two kinds of reference guide the choice. A materia medica collects drug pictures alphabetically, and Hahnemann arranged the first symptomatic one. A repertory is a quick-reference version that indexes symptoms and their remedies. The first was Georg Jahr's Symptomenkodex, published in German in 1835 and translated into English in 1838. More than 118 repertories now exist in English, and the one by James Tyler Kent is among the most used.

  The ingredients come from animals, plants, minerals and synthetic sources, usually under Latin names. Arsenicum album is arsenic oxide. Natrum muriaticum is table salt. Lachesis muta is the venom of the bushmaster snake, and thyroidinum is thyroid hormone. Homeopathic pills are made of an inert base, often lactose, with a drop of liquid preparation allowed to evaporate on it.

  Offshoots stretch the idea further. Isopathy uses nosodes, made from diseased products such as discharges, blood and tissue. Some modern homeopaths use "imponderables", which are said to capture X-rays or sunlight in alcohol or lactose. Electrohomeopathy supposedly extracts electric bio-energy from plants. In 2012 the Allahabad High Court in Uttar Pradesh, India, declared it quackery and stopped recognizing it as a system of medicine. Edward Bach developed the best-known flower preparations, made by exposing flowers in water to sunlight.

  Paper preparations go further still. Names of substances and dilutions are written on paper, then pinned to clothing, tucked in pockets or set under glasses of water. Classical homeopaths themselves have called such practices unfounded and verging upon magic and superstition.

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• 5. Rise and Return

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  Hans Birch Gram, a student of Hahnemann, carried homeopathy to the United States in 1825. The first American homeopathic school opened in 1835, and the American Institute of Homeopathy was established in 1844. By 1900 the country had 22 homeopathic colleges and 15,000 practitioners.

  Part of the appeal was the competition. Treatments of the time, including bloodletting and purging, were often ineffective and harmful. Homeopathic preparations were ineffective too, but they were rarely detrimental, so patients were less likely to be hurt by their own treatment. During 19th-century epidemics such as cholera, death rates in homeopathic hospitals were often lower than in conventional ones. The relative success of homeopathy may have helped push medicine away from bloodletting and purging, toward more effective, science-based care.

  Criticism arrived early. In 1843 Sir John Forbes, physician to Queen Victoria, called the tiny doses an "outrage to human reason". James Young Simpson wrote in 1853 of "No poison, however strong or powerful, the billionth or decillionth of which would in the least degree affect a man or harm a fly." Holmes published an essay in 1842 titled Homœopathy and Its Kindred Delusions. In 1867 the French Homeopathic Society observed that some leading European homeopaths were abandoning infinitesimal doses and no longer defending them. The last American school teaching only homeopathy closed in 1920.

  The decline did not last. By the 1950s the United States had only 75 solely homeopathic practitioners. By the mid to late 1970s, sales at some homeopathic companies had grown tenfold. Some homeopaths credit the Greek homeopath George Vithoulkas, who researched and refined the practice in that decade. Edzard Ernst and Simon Singh link the revival to the rise of the New Age movement. Bruce Hood suggests that long consultations and a taste for "natural" products also played a part.

  Politics helped in the United States. The Food, Drug, and Cosmetic Act of 1938 recognized homeopathic preparations as drugs. Its sponsor was Royal Copeland, a New York senator and homeopathic physician. Academics and Ernst report that the Nazi regime in Germany favoured homeopathy and spent large sums researching how it might work, without a positive result. Late in the century, William T. Jarvis of the National Council Against Health Fraud called homeopathy "a fraud perpetrated on the public with the government's blessing, thanks to the abuse of political power of Sen. Royal S. Copeland."

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• 6. Testing the Claims

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  In 1988 the French immunologist Jacques Benveniste, working at INSERM, published a paper in the journal Nature. It claimed that basophils released histamine when exposed to a homeopathic dilution of anti-immunoglobulin E antibody. Nature assembled an independent investigative team. The team found the experiments "statistically ill-controlled" and said interpretation was "clouded by the exclusion of measurements in conflict with the claim". It added: "We believe that experimental data have been uncritically assessed and their imperfections inadequately reported."

  Madeleine Ennis later reported, in studies from 2001 and 2004, that dilutions of histamine affected basophil activity. A Horizon programme had British scientists try to repeat the first of these, and they could not. A 2007 systematic review of high-dilution experiments found that none of the positive results could be reproduced by all investigators.

  Broader reviews point the same way. A 1998 medical review called homeopathy "placebo therapy at best and quackery at worst". A 2002 review of reviews found that higher-quality trials tended to give less positive results. A 2005 meta-analysis in The Lancet reached the same conclusion. A 2010 review of the best evidence by the Cochrane Collaboration found it "fails to demonstrate that homeopathic medicines have effects beyond placebo." The UK House of Commons Science and Technology Committee found no compelling evidence of any effect other than placebo.

  Australia's National Health and Medical Research Council completed a comprehensive review in 2015. It found "no health conditions for which there was reliable evidence that homeopathy was effective." The European Academies' Science Advisory Council reported in 2017 and raised concerns about quality control. A 2017 systematic review and meta-analysis found that the most reliable evidence did not support non-individualized homeopathy.

  One book pointed the other way. A 2011 volume, purportedly financed by the Swiss government, concluded that homeopathy was effective and cost efficient. It was found to be scientifically, logically and ethically flawed, and most of its authors had conflicts of interest. The Swiss Federal Office of Public Health later said it was published without the government's consent.

  Publication bias clouds the record. In alternative medicine journals, just 5% of articles in the year 2000 reported null results. Several officials have spoken bluntly. Dame Sally Davies, Chief Medical Officer for England, called homeopathic preparations "rubbish". In 2013 Mark Walport, the UK Government Chief Scientific Adviser, said "homeopathy is nonsense, it is non-science." Michael Baum and Edzard Ernst called it "among the worst examples of faith-based medicine".

  Why, then, do people report feeling better? The explanations include the placebo effect and the care shown in a long consultation. Many illnesses clear up on their own with time. Symptoms often cycle, and people seek help at their worst, so they would improve anyway, a pattern called regression towards the mean. Some patients also receive standard medical care at the same time. Others stop an unpleasant conventional treatment on a homeopath's advice and feel better, even though the underlying disease remains untreated and still dangerous.

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• 7. Harm and Ethics

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  In 2016 the American Food and Drug Administration issued a safety alert about homeopathic teething gels and tablets. An earlier investigation had found them improperly diluted, with "unsafe levels of belladonna". Reports of serious adverse events in children were "consistent with belladonna toxicity". Belladonna, arsenic and poison ivy are among the poisons used in some preparations. In rare cases the original ingredients are present at detectable levels, through improper preparation or deliberately low dilution. Instances of arsenic poisoning have occurred. In 2009 the agency advised people to stop using three discontinued Zicam cold remedies, which could permanently damage the sense of smell.

  The larger danger is delay. Patients who choose homeopathy over evidence-based medicine risk missing timely diagnosis and effective treatment for serious conditions such as cancer. In 2009 the World Health Organization official Mario Raviglione criticized the use of homeopathy to treat tuberculosis. The organization warned against it for depression, HIV and malaria. The Russian Commission on Pseudoscience said patients "spend significant amounts of money, buying medicines that do not work and disregard already known effective treatment."

  The idea of "suppression" feeds this risk. In 1978 Anthony Campbell, a consultant physician at the Royal London Homeopathic Hospital, criticized George Vithoulkas for claiming that antibiotic treatment would drive syphilis deeper into the body. Studies show that penicillin cures syphilis completely in more than 90% of cases.

  Vaccination is the most contested ground. Homeoprophylaxis, the use of homeopathy to prevent serious infectious disease, is especially controversial. Some homeopaths, particularly non-physicians, advise patients against immunization, and others suggest replacing vaccines with "nosodes". Hahnemann himself opposed such preparations. In December 2014 an Australian homeopathy supplier was found to have acted deceptively in promoting alternatives to vaccines. In 2015 the Federal Court of Australia imposed penalties on a homeopathic company that had made misleading claims about the whooping cough vaccine. In 2019 an investigation by the Telegraph found practitioners actively discouraging patients from vaccinating their children.

  Ethics have drawn sharp words. Michael Baum called homeopathy a "cruel deception". Edzard Ernst, the first professor of complementary medicine in the United Kingdom and a former homeopathic practitioner, objected to pharmacists withholding "necessary and relevant information" from customers. In 2013 the UK Advertising Standards Authority concluded that the Society of Homeopaths targeted vulnerable ill people and discouraged essential medical treatment. A 2006 review urged pharmacy colleges to require a course on the ethical dilemmas of recommending products that lack proven safety and efficacy data.

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• 8. Regulation and Markets

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  A 2019 report from the World Health Organization found that 100 of the 133 member states surveyed in 2012 acknowledged that their populations used homeopathy. Of those, 22 said the practice was regulated and 13 provided health insurance coverage. Rules vary widely. Homeopaths in the United Kingdom are under no legal regulation, so anyone can use the title. In Slovenia, a doctor who practices homeopathy risks losing the medical licence. In Germany, becoming a homeopathic physician requires a three-year training program.

  India recognizes homeopathy as a national system of medicine and lets remedies be sold with medical claims. The Central Council of Homoeopathy was established in 1973, and the National Institute of Homoeopathy followed in 1975. A national health survey in 2014 found that about 3% of the population used it.

  In Europe, public support is shrinking. The English National Health Service stopped funding homeopathic remedies in 2017. In 2018, prescriptions worth £55,000, less than 0.001% of the total prescribing budget, were still issued against its guidance. France phased out social security reimbursement in 2021, even though Boiron, the world's biggest maker of alternative medicine drugs, is based there. In 2016 the University of Barcelona cancelled its master's degree in Homeopathy, citing a lack of scientific basis, and the University of Valencia soon followed. In 2018 the Medical University of Vienna stopped teaching it. In January 2024 German health minister Karl Lauterbach announced plans to end statutory insurance coverage for homeopathic treatments.

  Switzerland shows how unsettled the question can be. The government withdrew coverage of homeopathy and four other treatments in 2005. After a referendum in 2009, the five were reinstated for a further six-year trial period.

  The money involved is large. Germany's homeopathic drug market is worth about €650 million, and a 2014 survey found 60% of Germans had tried it. France spent more than US$408 million on homeopathic products in 2008. The American market is worth about US$3 billion a year. A 2011 national survey estimated that 5 million American adults and 1 million children used homeopathy, mostly on their own for colds and muscle and joint pain. Walmart, CVS and Walgreens sell products packaged to resemble conventional medicines.

  That packaging led to lawsuits. The Center for Inquiry sued CVS in 2018 and Walmart in 2019 for consumer fraud. In 2019 the FDA removed an enforcement policy that had permitted unapproved homeopathics to be sold, and no homeopathic product is approved by the agency. In 2015 the Canadian Broadcasting Corporation applied for a licence for a made-up children's drug and received a government-approved one.

  Animals are not spared. A 2016 review by scientists from the University of Kassel found too little evidence to support homeopathy for infectious disease in livestock. Animals do not respond to consultation or expectation, so any apparent benefit loses its usual explanation. The Australian Veterinary Association lists homeopathy among its "ineffective therapies", and the British Veterinary Association says it "cannot endorse" it.

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