The term homeopathy is derived from the Greek words homeo (similar) and pathos (suffering from disease). ⁽¹⁾  The first basic principles of homeopathy were formulated by the German physician Samuel Hahnemann in the late 1700s. Curious about why quinine could cure malaria, Hahnemann ingested quinine bark and experienced alternating bouts of chills, fever, and weakness, the classic symptoms of malaria. From this experience he derived the principle of similars, or "like cures like": that is, a substance that can cause certain symptoms when given to a healthy person can cure those same symptoms in someone who is sick.

Hahnemann spent the rest of his life extensively testing, or "proving," many common herbal and medicinal substances to find out what symptoms they could cause. He also began treating sick people, prescribing the medicine that most closely matched the symptoms of their illness. The information from this experimentation has been carefully recorded and makes up the homeopathic materia medica, a listing of medicines and their indications for use. According to the Homeopathic Pharmacopoeia of the United States, homeopathic medicines, or remedies, are made from naturally occurring plant, animal, and mineral substances.

By the end of the 19th century, homeopathy was widely practiced in the United States, when there were 22 homeopathic medical schools, more than 100 homeopathic hospitals, and an estimated 15 percent of physicians practicing homeopathy. The practice of homeopathy (along with other types of alternative medicine) declined dramatically in the United States following the publication of the Flexner Report in 1910, which established guidelines for the funding of medical schools. These guidelines favored AMA-approved institutions and virtually crippled competing schools of medicine. In the past 15 years, however, there has been a resurgence of interest in homeopathy in this country. It is estimated that approximately 3,000 physicians and other health care practitioners currently use homeopathy, and a recent survey showed that 1 percent of the general population, or approximately 2.5 million people, had sought help from a homeopathic doctor in 1990 (Eisenberg et al., 1993).

Those who are licensed to practice homeopathy in the United States vary according to state-by-state "scope of practice" guidelines, but they include M.D.s, D.O.s, dentists, naturopaths (N.D.s), chiropractors, veterinarians, acupuncturists, nurse practitioners, and physician assistants. Three states now have specific licensing boards for homeopathic physicians: Arizona, Connecticut, and Nevada. Specialty certification diplomas for those prescribing homeopathic drugs are established through national boards of examination for M.D.s/D.O.s and N.D.s. Self-help as well as professional training courses in homeopathy are offered through the National Center for Homeopathy (NCH) in Alexandria, Virginia. NCH serves as an umbrella organization for consumer support of homeopathy as well as a focus for coordination among an increasing number of organizations and specialty societies offering lay and professional training programs in homeopathy.

Homeopathic medicine also is currently widely practiced worldwide, especially in Europe, Latin America, and Asia. In France, 32 percent of family physicians use homeopathy, while 42 percent of British physicians refer patients to homeopaths (Bouchayer, 1990; Wharton and Lewith, 1986). In India, homeopathy is practiced in the national health service, and there are more than 100 homeopathic medical colleges and more than 100,000 homeopathic physicians (Kishore, 1983).

In the United States today, the homeopathic drug market has grown to become a multimillion-dollar industry; a significant increase has occurred in the importation and domestic marketing of homeopathic drugs. Homeopathic remedies are recognized and regulated by the FDA and are manufactured by established pharmaceutical companies under strict guidelines established by the Homeopathic Pharmacopoeia of the United States. Products that are offered for the treatment of serious conditions must be dispensed under the care of a licensed practitioner. Other products offered for the use of self-limiting conditions such as colds and allergies may be marketed as over-the-counter drugs.

Homeopathy is used to treat both acute and chronic health problems as well as for health prevention and promotion in healthy people. Homeopathic medicines are prescribed on the basis of a wide constellation of physical, emotional, and mental symptoms. The one remedy that most closely fits all of the symptoms of a given individual is called the similimum for that person. Thus, homeopathic treatment is individualized, and two or more people with the same diagnosis may be given different medicines, depending on the specific symptoms of illness in each person. A person with a sore throat, for instance, may need one of six or seven common remedies for sore throats, depending on whether the pain is worse on the right or left side, what time of day it is worse, what the person's mood is, and his or her body temperature, thirst, and appetite (Jouanny, 1980).

Hahnemann also discovered that if the homeopathic remedies were "potentized" by diluting them in a water-alcohol solution and then shaking, side effects could be diminished. He found that after the medicines were potentized to high dilutions, there was still a medicinal effect, and side effects were minimal. Some homeopathic medicines are diluted to concentrations as low as 10^-30 to 10^-20,000. This particular aspect of homeopathic theory and practice has caused many modern scientists to reject homeopathic medicine outright. Critics of homeopathy contend that such extreme dilutions of the medicines are beyond the point at which any molecules of the medicine can theoretically still be found in the solution (When to believe..., 1988).

On the other hand, scientists who accept the validity of homeopathic theory suggest several theories to explain how highly diluted homeopathic medicines may act. Using recent developments in quantum physics, they have proposed that electromagnetic energy may exist in the medicines and interact with the body on some level (Delinick, 1991). Researchers in physical chemistry have proposed the "memory of water" theory, whereby the structure of the water-alcohol solution is altered by the medicine during the process of dilution and retains this structure even after none of the actual substance remains (Davenas et al., 1988).

Basic science research in homeopathy has primarily involved investigations into the chemical and biological activity of highly diluted substances. The most thought-provoking research has involved observation of the physiological responses of living systems to homeopathically potentized solutions. For example, in the 1920s a German researcher conducted a series of studies spanning 12 years in which he showed periodic variations in the growth patterns of plants that had been exposed to a series of homeopathic dilutions of metallic salts (Kolisko, 1932). With the focus of modern biological laboratory research on cellular and organ function, homeopathic studies have more recently been conducted in this area. Such laboratory studies have shown positive effects of homeopathically prepared microdoses. (Davenas et al., 1987), (Cazin et al., 1987), (Doutremepuich et al., 1987), (Davenas et al., 1988; Poitevin et al., 1988).

Furthermore, recent clinical trials in Europe have suggested a positive effect of homeopathic medicines on such conditions as allergic rhinitis (Reilly et al., 1986), fibrositis (Fisher et al., 1989), and influenza (Ferley et al., 1989), while an earlier study showed no apparent effect in the treatment of osteoarthritis by a homeopathic medicine (Shipley et al., 1983). The British Medical Journal published a meta-analysis in 1992 of homeopathic clinical trials, which found that 15 of 22 well-designed studies showed positive results. This study concluded that more methodologically rigorous trials should be done to address the question of efficacy of homeopathic treatment (Kleijnen et al., 1991). A recent double-blind study comparing homeopathic treatment with placebo in the treatment of acute childhood diarrhea found a statistically significant improvement in the group receiving the homeopathic treatment (Jacobs et al., 1993).

Homeopathic research study design has used different methodologies depending on the question being asked. One of the earliest studies of homeopathy in a peer-reviewed conventional medical journal asked the question, "Is the homeopathic medical system taken as a whole more effective or less detrimental than another treatment or placebo in the condition studied?" In this study, which focused on rheumatoid arthritis, 195 patients who had previously been treated with nonsteroidal anti-inflammatory drugs were allocated to placebo treatment or active treatment. The active-treatment population then was divided between aspirin and a homeopathic medication. The homeopathic doctors were allowed to prescribe any medication at whatever interval, frequency, or potency they considered appropriate.

The trial was conducted for a year, and by the end of the year almost 43 percent of the homeopathic treatment group had stopped other treatments and were judged to have improved since the beginning of the study. Another 24 percent of the homeopathic group improved, but they continued on their conventional medications. In contrast, only 15 percent of the aspirin group were maintained and improved on the treatment. The entire placebo group had dropped out within 6 weeks.

This study, however, was criticized on some methodological grounds -- principally that the homeopathic prescribers were more committed to the treatment and the patients were easily able to determine who was in the placebo group (Gibson et al., 1978). Subsequently, the same researchers conducted another trial of this type, in which a specific disease was subjected to homeopathic treatment by any one of a number of clinically indicated homeopathic medications. This time, a placebo-controlled, double-blind study showed that the improvements among the homeopathically treated patients were statistically more significant than those of the placebo group (Gibson et al., 1980).

A second type of homeopathic study has been used to ask a more specific question, namely, Is a particular homeopathic medication more effective than another treatment or placebo for a particular disease? Fisher and colleagues (1989) asked this question in a study of primary fibromyalgia, a type of inflammation; patients who met recognized diagnostic criteria for fibromyalgia were further stratified as patients for whom a particular homeopathic medicine, rhus toxicodendron 6C, was homeopathically indicated. Patients with the active treatment were better on all variables, and a number of their tender points were reduced by 25 percent at the end of 4 weeks of active treatment in comparison with controls.

In a similar study, Reilly and colleagues (1986) used homeopathic medications with hay fever patients to address the issue of whether homeopathic medications are in fact placebos. The researchers directly treated matched groups of approximately 70 patients with a homeopathic medication made from mixed grass pollens at the dilution of one part in 10⁶⁰. This was done to address the assertion that a potency lacking in any of the original substances could act as more than a placebo. Patients took one tablet twice daily of either placebo or the test drug and were free to use a standard antihistamine at any time during the 5-week study. Only the homeopathically treated group showed a clear reduction in symptoms, and in comparison with the placebo-treated group, twice as many of the homeopathically treated patients had discontinued their antihistamines. This study also demonstrated that even a simple study design requires careful analysis of potential confounding variables, including the clinical observations that some homeopathically treated patients experience temporary aggravation of their symptoms before achieving a sustained improvement.

A third type of study simply looks at comparative utilization figures for homeopathic practitioners in a health care system with or without attention to the comparative clinical outcomes. For example, in France, research on cost-effectiveness has shown that the annual cost to the social security system for a homeopathic physician is 54 percent lower than the cost for a conventional physician. Moreover, the same study found that the price of the average homeopathic medicine is one-third that of standard drugs (CNAM, 1991).

Recent surveys in the United States found that most homeopathic patients seek care for chronic illnesses (Jacobs and Crothers, 1991) and that homeopathic physicians spend twice as much time with their patients, order half as many laboratory tests and procedures, and prescribe fewer drugs (Jacobs, 1992). Since treatment of chronic illness accounts for a large proportion of health care expenditures in the United States, the cost-effectiveness of homeopathic medicine should be investigated by comparing homeopathy with conventional treatments for specific chronic illnesses such as recurrent childhood ear infections, allergies, arthritis, headaches, depression, and asthma. Clinical outcomes should be measured as well as such factors as utilization of health services, number of missed days of work or school, patient satisfaction, and overall cost of health care. This research will help determine whether incorporating homeopathy into the national health care scheme would significantly reduce health care costs.

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Poitevin, B., E. Davenas, and J. Benveniste. 1988. In vitro immunological degranulation of human basophils is modulated by lung histamine and apis mellifica. Br. J. Clin. Pharmacol. 25:439-444.

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