Health: When the poison is the cure

Homoeopathy relies on the `like-cures-like' principle and uses remedies so dilute that not a molecule may remain. Science finds it suspect, but many patients seem to benefit. Professor Edzard Ernst continues his series on complementary medicine

Homoeopathy: what is it? About 200 years ago a German physician, Samuel Hahnemann, began to conduct a series of experiments on himself, on family and on friends. These tests led him to develop a system of medicine which he later called "homoeopathy".

Homoeopathy is based essentially on two main assumptions. The first is the often quoted "law of similars" or "like-cures-like principle". It is based on a simple idea: if a healthy individual takes a given medication and experiences a symptom or side effect from it (say, a headache) this very medication is effective in curing the headache in patients who suffer from it. There are many examples to suggest that the "law of similars" does occasionally apply - most profanely perhaps, a hangover after a heavy night can be alleviated by a drink in the morning. Homoeopaths, however go far beyond this: they claim that the "law of similars" applies universally. Critics insist that this is not true.

The second assumption states that by repeatedly diluting and shaking a remedy (homoeopaths call this process succession and potentisation), it does not become less powerful, as one would expect, but more effective. Thus remedies that do not contain a single molecule of the original substance are seen as potent treatments.

Scientists point out that where there is no molecule, there can be no effect. Homoeopaths counter that their remedies do not rely on pharmacological action in the traditional sense but that information or "energy" is somehow passed on from the original material to the dilutent. This represents the active principle even in the absence of molecules - a theory that is often referred to as the "memory of water".

Hahnemann was adamant that his form of homoeopathy is the only permissible way of practising medicine. But soon, all sorts of variations of the common homoeopathic theme emerged, and today we are confronted with a confusing array of homoeopathic practices. In the UK there are two kinds of homoeopaths - physicians who have first studied conventional medicine and later take up homoeopathy, and non-medically qualified homoeopaths who usually (but not always) have studied the principles of homoeopathy for several years. The latter by far outnumber the former, and altogether about 2,000 homoeopaths are registered in Britain.

To see a homoeopath would cost between pounds 30 and pounds 50. Normally, several repeat visits are recommended. The remedies prescribed are relatively inexpensive.

What happens during a homoeopathic consultation?

Homoeopaths assess their patients in great detail to find the remedy that fits optimally. This entails lengthy history-taking with all sorts of unusual questions. Homoeopaths are less interested in their patient's medical diagnosis than regular physicians. They also place much less emphasis on physical examinations or laboratory tests.

Treatment normally consists of tiny little pills, which have to be taken according to a prescribed, sometimes hourly, schedule. Many, but not all, homoeopathic remedies are plant-based; several medicines are derived from highly poisonous substances, but are given in such dilute form that no toxic reactions would occur. Some homoeopaths only prescribe single remedies (as taught by Hahnemann); others combine medications. Some ask patients to avoid certain foodstuffs (eg coffee) and conventional medications (eg cortisone). Others are more liberal on this point.

What is homoeopathy for?

Homoeopaths claim that they don't treat diseases, but individuals. Thus any condition might be attended homoeopathically. In practice, homoeopaths tend to treat mild to moderately severe, often (but not always) chronic ailments: headaches, eczema, asthma and night cramps are examples which are thought to respond well. Many patients swear by homoeopathy, and they feel that they are helped by it.

About 100 rigorous clinical trials of homoeopathy have been published. Lumped together, their results seem to imply that homoeopathic remedies are more than purely placebos. However, it is debatable whether it makes sense analysing these highly diverse studies in this global fashion. More focused assessments (systematic reviews) have shown no convincing evidence that highly dilute homoeopathic remedies prescribed according to the "law of similars" are more than placebos; that any defined medical condition responds better to homoeopathic remedies than to placebo; or that widely used remedies (eg arnica) have clinical effects that differ from those of placebo.

What are the potential risks?

Most people assume that homoeopathy is entirely risk-free. This may not be quite true. With highly dilute remedies one would not expect any toxic reactions. But less dilute remedies can, of course, cause side effects. Allergies, for instance, have been observed repeatedly.

Provided that the optimal remedy has been prescribed, homoeopaths would expect an aggravation of the symptoms in about one-quarter of their patients. This can result, according to homoeopathic beliefs, in a dramatic worsening of the condition. For a homoeopath such an event is interpreted as a sign that the right remedy has been identified and that the healing process has begun. The patient, however, is likely to perceive it as an adverse event.

Those homoeopaths who strictly adhere to the teachings of Hahnemann view homoeopathy as a true alternative to orthodox medicine. They might advise against taking mainstream treatments.

Patients are put at risk when their condition requires conventional therapy and they are prevented from receiving it. An example is the advice of many (if not most) non-medically qualified homoeopaths against immunisation of children. In the UK, such advice is currently the most frequent reason for not adhering to immunisation campaigns. This puts at risk not only those who follow such recommendations, but it also endangers the immunity of whole populations.

Even though it is not entirely free of risks, many patients are undoubtedly helped by homoeopathy. Currently we don't know to what extent this is due to the empathetic therapeutic encounter during a lengthy homoeopathic consultation or due to the specific therapeutic effects of homoeopathic remedies.

Where to go for help

The Homoeopathic Trust,

15 Clerkenwell Close,

London EC1R 0AA

Society of Homoeopaths

2 Artizan Road

Northampton NN1 4HU

Useful reading :

Homoeopathy: A Critical Appraisal, Ernst E, ed Hahn EG (Oxford, Butterworth Heinemann, 1998)

People are Pets, Hunter F, Kayne S (Br Horn Ass 1997)

Why patients may find homoeopathy helpful

The therapeutic encounter is helpful - the time spent with the practitioner can be beneficial on account of his/her understanding and empathy.

The expectation of the patient (or the practitioner) results in a markedly symptomatic improvement.

Symptoms disappear after some time, even though this is as likely to occur without intervention (in analogy, this also applies to other complementary therapies).