What is Homeopathy?

Homeopathy (from the Greek hómoios- ὅμοιος- ("like-") + páthos πάθος ("suffering")) is a form of alternative medicine first expounded by Samuel Hahnemann in 1796, that treats a disease with heavily diluted preparations created from substances that would ordinarily cause effects similar to the disease's symptoms. These substances are serially diluted, with shaking ("succussing") between each step, under the belief that this increases the effect of the treatment. This dilution is usually quite extensive, and often continues until no molecules of the original substance are likely to remain.

As well as the disease itself, homeopaths may use aspects of the patient's physical and psychological state to select between treatments.

Reference books, known as reperatories, which have been created by homeopaths, are then consulted, and a remedy selected based from the index of symptoms. Homeopathic remedies are generally considered safe, with rare exceptions. However, homeopaths have been criticized for putting patients at risk with advice to avoid conventional medicine, such as vaccinations, anti-malarial drugs, and antibiotics. In many countries, the laws that govern the regulation and testing of conventional drugs do not apply to homeopathic remedies.

Claims of homeopathy's efficacy (beyond the placebo effect) are unsupported by the collective weight of scientific and clinical evidence. Specific pharmacological effect with no active molecules is scientifically implausible and violates fundamental principles of science, including the law of mass action. Supporters claim a few high-quality studies support the efficacy of homeopathy; however, the studies they point to are not definitive and have not been replicated, several high-quality studies exist showing no evidence for any effect from homeopathy, and studies of homeopathic remedies have generally been shown to have problems that prevent them from being considered unambiguous evidence for homeopathy's efficacy. The lack of convincing scientific evidence supporting homeopathy's efficacy and its use of remedies lacking active ingredients have caused homeopathy to be described as pseudoscience and quackery.