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Other common name(s): homeopathic medicine

Scientific/medical name(s): none


Homeopathy is based on the idea that if large doses of a substance cause a symptom, very small doses of that same substance will cure it. Homeopathic remedies are water-based or alcohol-based solutions containing tiny amounts of naturally occurring plants, minerals, animal products, or chemicals. The term “homeopathy” comes from the Greek words homoios (meaning similar) and pathos (meaning suffering).


While homeopathy appears to be safe, available published studies do not show that homeopathic remedies are effective in treating cancer. A few studies in humans suggest that they might help with some of the side effects of cancer or its treatment, but other studies show little or no effect.

How is it promoted for use?

Homeopathy is most often promoted for use in treating chronic or self-limiting problems such as arthritis, asthma, colds, flu, and allergies. However, some supporters believe that homeopathy can be used to treat and cure cancer.

Some practitioners claim homeopathy can help cancer patients by reducing pain, improving vitality and well-being, stopping the spread of cancer, and strengthening the immune system. Some claim it can lessen certain symptoms and side effects from radiation therapy, chemotherapy, and hormone therapy, such as infections, nausea, vomiting, mouth sores, hot flashes, hair loss, depression, weakness, and ascites (collection of fluid in the abdomen).

Proponents claim that homeopathic solutions, even though they may contain only small quantities (or none) of the original ingredient, contain a “memory” of the substance that somehow interacts with the body to cure illness. It is also believed that shaking or diluting a homeopathic solution releases the essence, or healing life force, of the material.

Some practitioners compare homeopathy to the beliefs of ayurvedic and traditional Chinese medicine, which claim a need to bring the body into balance in order to restore health and wellness (see Ayurveda and Chinese Herbal Medicine). Many supporters of homeopathy admit that they do not know how the treatments work, but insist that future research will unlock the mystery.

What does it involve?

Homeopathy is based largely on the “law of similars,” or the notion that “like cures like.” In other words, a substance that causes symptoms of illness in a healthy person can relieve those same symptoms in a sick person when given in very small amounts. For example, a patient complaining of vomiting and diarrhea might receive a solution containing tiny amounts of thorn apple, since larger amounts of that herb cause those symptoms.

The second important tenet of homeopathy is the “law of infinitesimals,” which states that the more a homeopathic solution is diluted, the more powerful it becomes.

When a patient complains of certain symptoms, the homeopath consults a reference guide that lists thousands of individual symptoms, and searches for an entry that matches the patient's description. The remedy, which is determined by the person's health history and symptoms, is called the “simillium.” The practitioner then takes this simillium – an extract of the plant, mineral, animal product, or chemical remedy that matches the patient's symptoms – and repeatedly dilutes it, usually in water.

In the terminology of homeopathy, adding 1 part of the extract to 9 parts water yields a 1X solution (X is the Roman numeral for 10), while adding 1 part of the extract to 99 parts water yields a 1C solution (C is the Roman numeral for 100). (The 1X and 1C homeopathic dilutions are called 1:10 and 1:100 dilutions, respectively, in conventional chemistry.) The solution is mixed vigorously, and 1 part of it is diluted again in 9 (or 99) parts water, yielding a 2X (or 2C) solution, and so on. A 6X dilution, for example, would result in 1 part extract per 1 million parts water.

Each solution may go through the dilution process as many as 30 to 50 times, to the point where it may be very unlikely that even a single molecule of the original extract remains in a dose of the remedy. Homeopaths believe that even if this is the case, the remaining water retains some type of “memory” of the extract. After the dilution process is complete, the patient is given the remedy in liquid or pill form, which may be swallowed, placed under the tongue, or sometimes be placed on the skin.

Though homeopathy began with providers making and prescribing the remedies for individual patients, they are increasingly manufactured and sold directly to the consumer. Homeopathic remedies in the US are now mainly sold over the counter, in health food stores, or via internet sources.

What is the history behind it?

Some of the ideas that form the basis of homeopathy go back to the ancient Greeks, but the more recent version is credited to the German physician Samuel Hahnemann. He developed homeopathy in the early 1800s as a more civilized alternative to some of the harsh medical practices of the time, such as bloodletting and purging. Dr. Hahnemann believed a substance that caused specific symptoms in a healthy person could cure those same symptoms in a sick person.

To determine the specific effects of each material, Dr. Hahnemann and his assistants conducted “provings,” during which healthy people ingested plants, minerals, and other materials, then noted what symptoms resulted. From these experiments, Hahnemann compiled a reference book containing descriptions of the effects of various materials and recommended homeopathic remedies.

Hahnemann further believed that dilution made remedies more potent, so he gave his patients diluted doses of the substances that caused symptoms. According to one doctor (Ernst, 2007), Hahnemann also set forth the theory that all diseases originate from the “itch,” from gonorrhea, or from syphilis.

In the 1800s, homeopathy may have been better for people than mainstream medicine in some instances, if for no other reason than it did less harm than some of the harsh and ineffective practices used at the time. Homeopathy remained popular through the beginning of the 20th century, when a better understanding of what caused many diseases and how they could be treated emerged.

The 1938 Food, Drug, and Cosmetic Act required that all drugs be tested for safety before being approved by the U.S. Food and Drug Administration (FDA) and sold to the public. This act also allowed any homeopathic remedy that was included in a certain US reference book to be considered a legal drug. But unlike standard drugs, homeopathic remedies do not have to submit proof to the FDA that they are safe and effective before they are sold

Along with the general growth of complementary and alternative methods in recent years, homeopathy has become a more popular alternative form of therapy in the United States.

What is the evidence?

The assumptions upon which homeopathy are based, such as on the “law of similars” and the “law of infinitesimals” are not based on modern scientific principles. According to a 2009 article, “These axioms are not only out of line with scientific facts but also directly opposed to them. If homeopathy is correct, much of physics, chemistry, and pharmacology must be incorrect.”

Few laboratory studies of homeopathic remedies have been published, and results are sometimes conflicting. In two 2006 studies researchers found that homeopathic solutions had no effect on breast or prostate cancer cells growing in laboratory cultures, but it appeared that similar solutions slowed the growth of prostate cancer cells that were introduced into rats. Based on available published evidence in the medical literature as of early 2013, this success has not been reproduced.

There is no reliable evidence showing that homeopathic remedies can treat cancer in humans. The basic premises of homeopathy, developed more than 200 years ago, are not in agreement with modern scientific principles. Some researchers suggest, however, that homeopathy may result in helpful effects for patients who believe the treatment is working--a phenomenon known as the placebo effect or expectation effect. One study on the increased use of complementary therapies by people with cancer showed that while certain complementary therapies had no actual anti-tumor effect, patients reported psychological improvement including increased hope and optimism. The complementary therapies studied included homeopathy.

Some small clinical studies have hinted that homeopathic solutions may have some benefit in reducing certain side effects of cancer or its treatment. But the number of patients in the studies that reported benefits is typically small, the studies are not rigorously controlled, and few of them have been done. Higher-quality and better-controlled studies have found homeopathic solutions to be no better than a placebo. A 2006 review of published studies concluded that, “… analysis of published literature on homeopathy found insufficient evidence to support clinical efficacy of homeopathic therapy in cancer care.” An expert researcher later concluded that “there is no evidence at all that homeopathic remedies can change the natural history of any cancer,” and adds that there is no convincing evidence of benefit even for supportive cancer care. Further research would be needed before homeopathy could be considered likely to be useful for any aspect of cancer care.

Are there any possible problems or complications?

This product as sold as a homeopathic remedy in the United States. If sold without a prescription, a homeopathic remedy must be intended for self-limiting illnesses (such as a cold or muscle strain) rather than serious illness. These products are regulated as a special category of over-the-counter (OTC) drugs. A big difference between standard OTC drugs (such as aspirin or antibiotic ointments) and OTC homeopathic remedies is that detailed documents showing scientific proof of safety and effectiveness must be provided to the US Food and Drug Administration (FDA) before conventional standard OTC drugs are sold, but OTC homeopathic remedies aren't required to do this.

Although some homeopathic solutions contain toxic chemicals, they are typically thought to be present in amounts too small to present any danger. A 2012 review that surveyed the international medical literature found that there were some unexpectedly significant problems with certain homeopathic remedies. Apparently not all of these remedies were diluted enough to prevent problems due to allergic reactions, asthma, disturbed heart rhythms, drug interactions, ingesting heavy metals, and more. A number of these bad outcomes resulted in hospitalization, and even a few deaths.

Relying on this type of treatment alone, and avoiding or delaying conventional medical care for cancer, may have serious health consequences.

To learn more

More information from your American Cancer Society

The following information on complementary and alternative therapies may also be helpful to you. These materials may be found on our Web site (www.cancer.org) or ordered from our toll-free number (1-800-227-2345).

Dietary Supplements: What Is Safe?

The ACS Operational Statement on Complementary and Alternative Methods of Cancer Management

Complementary and Alternative Methods and Cancer

Placebo Effect

Learning About New Ways to Treat Cancer

Learning About New Ways to Prevent Cancer


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Note: This information may not cover all possible claims, uses, actions, precautions, side effects or interactions. It is not intended as medical advice, and should not be relied upon as a substitute for consultation with your doctor, who is familiar with your medical situation.

Last Medical Review: 02/12/2013
Last Revised: 02/12/2013