Alternative therapies: putting homeopathy under the clinical spotlight
Alternative facts: Little evidence that like cures like
Homeopathic remedies are generally considered safe, with few adverse effects reported by their users. Photograph: iStock
Homeopathy was developed by Samuel Hahnemann in the late 18th and early 19th century. The central idea of this system of alternative medicine is that “like cures like”, ie that fever could be cured by a treatment that would induce fever in a healthy person.
This was not a new concept, as it had been used by the ancient Greeks, but Hahnemann built on it by suggesting that treatments should be diluted to avoid aggravating illness and putting patients in danger. He also proposed that each patient should be studied in depth and the right homeopathic treatment specifically tailored for each individual person and symptoms.
The active drug in homeopathic remedies is serially diluted at one part in 100 parts of water, sugar or alcohol: this process is repeated a number of times, usually between six and 400, to give dilutions that might contain one part of active drug in one decillion (a one followed by 60 zeros).
It is generally considered that at such high dilution, no trace of the original active drug remains in the solution, but homeopaths believe this process actually makes the drug more potent. They believe the act of vigorously mixing the solution to dissolve the drug – known as succussion – activates it.
There is no evidence supporting the theory that a disease can be treated or cured by compounds that replicate its symptoms. Likewise, the idea that a therapy becomes more potent when it is more diluted goes against widely accepted laws of physics and chemistry.
This issue was addressed in the 1980s by Jacques Benveniste, who proposed that the diluted homeopathic remedy altered the structure of water in such a way that it retains the properties of the drug: this theory is commonly known as the memory of water.
However, water molecules are constantly moving and rearranging, making it highly unlikely that a structure would form which would be maintained for long periods of time, particularly once the homeopathic compounds are ingested.
Is it safe?
Homeopathic remedies are generally considered safe, with few adverse effects reported by their users. In a review of 41 trials including 6,055 patients, adverse effects of homeopathic therapy were found to be comparable to those caused by placebo control (a treatment that doesn’t have a therapeutic effect). Even when adverse effects have been reported, these have generally been mild and temporary. However, it cannot be excluded that homeopathic remedies could have adverse effects or interfere with conventional medical therapy, particularly those that haven’t been highly diluted.
What does the evidence say?
Homeopathic remedies have been tested extensively in clinical trials; however, these trials often do not provide reliable results. In a systematic review of clinical trials published in English between 1945 and 1995, less than a third used a placebo control while half of the studies failed to randomly assign patients to different treatment groups, opening the door to questions about how healthier patients were distributed to placebo or treatment arms.
Most studies were also carried out in small numbers of patients at a single site, limiting the estimation of the effects of treatment across the general population.
Flaws in the design or analysis of homeopathic clinical trials appear to be extended: another systematic review showed that only 16 out of 118 trials were found to be of sufficient quality for analysis.
This study also found that studies of high quality were more likely to report that the effects of homeopathic remedies were comparable to placebo than lower quality ones. Similarly, a systematic review of eight clinical trials involving 1,562 children receiving homeopathic treatment for upper respiratory tract infections found that all the studies assessed as high quality showed no beneficial effect of homeopathic treatment, while those assessed as low or uncertain (due to missing information) quality showed beneficial effects.
Systematic reviews of at least two trials of acceptable quality have shown there is not enough evidence of a beneficial effect of homeopathy for induction of labour, prevention and treatment of upper respiratory tract infections, chronic asthma, attention deficit/hyperactivity disorder (ADHD), prevention of influenza and influenza-like illness (using the homeopathic treatment Oscillococcinum), atopic eczema, warts, and hot flushes in women with a history of breast cancer.
Further work has found no beneficial effect of homeopathic treatment in the management of chronic rhinosinusitis, insomnia, anxiety and anxiety disorders, stress and headaches (including migraine).
Some systematic reviews have found possible beneficial effects of homeopathic treatment for certain conditions, although the evidence is not considered sufficient because of the low quality of the clinical trials. These conditions include constipation-predominant irritable bowel syndrome (using asafoetida), treatment of influenza and influenza-like illness (using Oscillococcinum), allergic rhinitis (using Galphimia glauca), fibromyalgia and chronic fatigue syndrome. Of these conditions, irritable bowel syndrome, allergic rhinitis and fibromyalgia are known to respond very well to placebo in conventional medicine clinical trials.
Homeopathic treatments tend to be individualised, designed specifically not just for the disease but also for the patient. Homeopathic consultation is considered a very important part of treatment, but this is hard to evaluate in clinical trials where the treatments that are assessed are standardised. However, one clinical trial performed on rheumatoid arthritis patients analysed the effect of homeopathic treatment with or without consultation and found that the consultation itself rather than the homeopathic remedy had beneficial effects on patients.
The time spent with the patient and the empathy displayed by the person responsible for treatment are of value to patients and could play a big role in the overall effects of homeopathic treatment, something that is difficult to measure in conventional clinical trials.
Overall, there is not enough evidence to establish that homeopathic remedies have an effect that is better than that of placebo in the clinical trials that have been carried up to date. Homeopathic remedies appear to be generally safe and might be of benefit in conditions that respond well to placebo.