Homeopathic medicine is a system of alternative medicine based on the idea that a substance causing symptoms in a healthy person can, in highly diluted form, treat similar symptoms in a sick person. Founded in the late 1700s by German physician Samuel Hahnemann, it remains widely available in pharmacies and health stores today, though no homeopathic product has been approved by the FDA for any medical use, and large-scale reviews have found no reliable evidence that it works better than a placebo.
The Two Core Principles
Homeopathy rests on two ideas that set it apart from conventional medicine. The first is “like cures like,” sometimes expressed with the Latin phrase similia similibus curantur. Hahnemann arrived at this principle after taking doses of cinchona bark (the source of quinine, used to treat malaria) and noticing it produced mild fever-like symptoms. He concluded that a substance producing certain symptoms in a healthy person could treat those same symptoms in someone who was ill.
The second principle is the “law of infinitesimals,” which holds that the smaller the dose, the more powerful the remedy. This is the opposite of how conventional drugs work, where a larger dose produces a stronger effect. Hahnemann believed that full-strength doses could worsen symptoms, and that progressive dilution, combined with vigorous shaking, would enhance the remedy’s healing properties while eliminating side effects.
How Remedies Are Made
Homeopathic products start with a source material drawn from plants (arnica, red onion, poison ivy, belladonna, stinging nettle), minerals (white arsenic, for example), or animals (such as crushed whole bees). This starting material is then repeatedly diluted and shaken in a process called potentization.
Two dilution scales are commonly used. The “C” (centesimal) scale dilutes the substance by a factor of 100 at each step: one part substance mixed with 99 parts water or alcohol, then shaken vigorously. That mixture is then diluted again at 1:100, and so on. The “X” or “D” (decimal) scale dilutes by a factor of 10 at each step. A product labeled 30C has gone through 30 rounds of 1:100 dilution, an extraordinarily high level of dilution.
At each stage, the mixture is struck against an elastic surface, a step called succussion. Homeopathic theory holds that this shaking transfers the “energy” or “vital force” of the original substance into the liquid, even as the physical material disappears.
The Dilution Problem
The math behind these dilutions creates a fundamental challenge. Based on well-established chemistry, once a remedy is diluted past 12C (or 24X), it becomes statistically unlikely that even a single molecule of the original substance remains in the solution. A common homeopathic potency of 30C far exceeds that threshold. In practical terms, most homeopathic products sold in stores are chemically indistinguishable from plain water or sugar pills.
Homeopathic practitioners argue that the water retains a “memory” of the original substance. No accepted scientific mechanism explains how this would work, and the concept contradicts core principles of chemistry and physics.
What the Evidence Shows
The most comprehensive review of homeopathy’s effectiveness came from Australia’s National Health and Medical Research Council, which examined evidence across dozens of health conditions. The conclusion was stark: there were no health conditions for which reliable evidence showed homeopathy was effective. No well-designed studies with adequate sample sizes found that homeopathic remedies produced greater improvements than a placebo or matched the results of conventional treatments. Of the conditions reviewed, the quality of evidence was rated low to very low for 56 out of 61.
In 2017, NHS England stopped funding homeopathy, citing the lack of evidence for its effectiveness. A High Court ruling in 2018 upheld that decision. These moves reflected a broader pattern among health authorities distancing public healthcare systems from homeopathic treatments.
Who Uses It
Despite the evidence gap, homeopathy has a substantial global following. A systematic review covering surveys in eleven countries found that the median 12-month usage rate among adults was about 3.9%, with a range of 0.7% to 9.8% depending on the country. In the U.S., UK, Australia, and Canada, usage rates ranged from about 1.7% to 4.4% and stayed relatively stable from 1986 through 2012. Switzerland reported the highest use, likely because homeopathy is covered under mandatory health insurance there.
Most adults who use homeopathic products self-prescribe them for colds and musculoskeletal pain, purchasing over-the-counter remedies rather than visiting a homeopathic practitioner.
Regulation in the United States
Under federal law, homeopathic products are technically subject to the same requirements as other drugs, including rules on approval, adulteration, and misbranding. In practice, however, no homeopathic product has been reviewed or approved by the FDA for any use. This means they have not been evaluated for safety, effectiveness, or quality by the standards applied to conventional medications.
In December 2022, the FDA issued guidance outlining a risk-based enforcement approach. Rather than attempting to regulate all homeopathic products equally, the agency said it would prioritize enforcement against products that raise safety concerns, contain potentially dangerous ingredients, claim to treat serious conditions like cancer, are marketed to vulnerable groups (children, pregnant women, the elderly), or are administered through non-standard routes like injection or eye drops.
Safety Risks
Because most homeopathic remedies are diluted to the point of containing no active molecules, they are often physically harmless. The real risks fall into two categories: what’s in the product and what the product replaces.
Quality control failures have led to documented harm. In 2017, the FDA alerted consumers that some homeopathic teething tablets contained excessive amounts of belladonna, a toxic plant compound. Published case studies have also linked homeopathic and traditional remedies to arsenic poisoning. One analysis found that two-thirds of homeopathic medicines sampled contained arsenic levels higher than indicated on their labels. Products made from toxic starting materials can be dangerous if the dilution process is inconsistent or improperly performed.
The other risk is indirect. People who rely on homeopathy for serious or life-threatening conditions may delay or avoid treatments with proven effectiveness. The FDA has specifically warned consumers not to rely on over-the-counter asthma products labeled as homeopathic, since these have not been evaluated for safety or effectiveness. For any condition where effective conventional treatments exist, substituting homeopathy can have real consequences.