Homeopathy

Homeopathy is a system of treatment devised in the 1790s by Samuel Hahnemann, and it remains one of the most widely used alternative therapies in Britain. It rests on three claims, and it is worth setting them out accurately before examining them, because they are frequently described in ways that make them sound like something else.

What it actually claims

Like cures like. A substance that produces a set of symptoms in a healthy person will, prepared in a particular way, treat those same symptoms in an ill person. The remedy is chosen to match the symptoms rather than the disease, which is why two people with the same diagnosis may be given different remedies.

The minimum dose. The substance is diluted repeatedly, with vigorous shaking at each step. The dilutions are extreme: a preparation labelled 30C has been diluted one part in a hundred, thirty times over, which is one part in ten followed by sixty zeros. At that dilution a preparation is very unlikely to contain even a single molecule of the original substance. Practitioners hold that the water retains some imprint of it. There is no known physical mechanism by which that could happen.

The single remedy. One carefully chosen preparation at a time, rather than several medicines for several symptoms.

It is also worth saying what homeopathy is not, because the confusion is extremely common. Homeopathy is not herbal medicine, and the two are not interchangeable terms for natural remedies. A herbal preparation contains pharmacologically active plant material in quantities that can have real effects, both wanted and unwanted, and can interact dangerously with prescribed medicines. A homeopathic preparation at typical dilutions contains, in material terms, nothing. Describing homeopathic remedies as "totally natural" treats the two as the same family, and they are not.

The analogy that does not hold

Writing on homeopathy very often defends the first principle by pointing at vaccination and at allergy injections: both involve giving a small amount of the thing that causes the problem, so the principle must be respectable.

The comparison fails on both counts.

Vaccines and allergen immunotherapy contain measurable, weighable quantities of the relevant substance — small compared with an ordinary exposure, not small compared with the limits of detection. The dose is there, it can be assayed, and the immune response it provokes can be measured in the blood afterwards. A 30C dilution contains no detectable quantity of anything.

And the principle is different. Vaccination teaches the immune system to recognise a specific pathogen by showing it part of that same pathogen; allergen immunotherapy gradually desensitises the immune system to the specific allergen. Neither works by matching symptoms, and neither involves giving a substance that mimics an unrelated illness. The mechanisms are described, measurable and specific.

One factual correction while on the subject: an injected flu vaccine does not contain live influenza virus, so it cannot be described as receiving "a small amount of the flu".

What the evidence says

Homeopathy has been studied a great deal, which is unusual for an alternative therapy and makes a clear answer possible.

The most thorough assessment remains the Australian national health research council's review, which examined fifty-seven systematic reviews covering sixty-eight conditions. Its conclusion was that the evidence "fails to demonstrate that homeopathy is an effective treatment for any of the reported clinical conditions in humans." A later NHS England review of the trials published since found that they did not change that conclusion.

The pattern within the evidence is the informative part. Pooled analyses of homeopathy trials do sometimes produce a small positive result — and the trials driving it are almost all at unclear or high risk of bias, while the trials conducted most rigorously find no effect. Publication bias is present, meaning negative trials are less likely to have been published. That combination is the signature of an ineffective treatment rather than a subtly effective one.

On specifics: the homeopathic influenza preparation sold widely in pharmacies has no good evidence for treating or preventing flu, and none at all for prevention. Homeopathic arnica after knee surgery showed no benefit. For headache and migraine it was no better than placebo. The House of Commons Science and Technology Committee, reviewing the field in 2010, concluded that homeopathic products perform no better than placebo.

NICE has not recommended homeopathy for any condition, and advises against it specifically for glue ear, for inducing labour, and for urinary symptoms in men. NHS England lists homeopathic remedies among the items that should not routinely be prescribed in primary care. It is not available on the NHS.

One point about the packaging. Homeopathic products in the UK can carry a registration from the medicines regulator, and that registration scheme does not require any evidence that the product works. It covers quality and safety and the acceptability of the claims made on the label. A registration number on a box is not a statement of effectiveness, though it reasonably looks like one.

Getting worse before getting better

Homeopathic theory holds that symptoms may intensify before they improve — an "aggravation", taken as a sign that the remedy is working.

Two things are worth knowing about that. The first is that the evidence for aggravations happening at all is not strong enough to confirm them, which puts the doctrine in an odd position: the thing it predicts does not reliably occur.

The second is what the doctrine does. It converts the most obvious evidence that a treatment is failing — the patient getting worse — into evidence that it is succeeding. That makes the system impossible to disprove from the inside, and it is the mechanism by which a person with something progressive carries on with an inert treatment past the point where they should have stopped.

Safety, honestly

The preparations themselves are, at typical dilutions, inert, and trials find side effects at much the same rate as placebo. The direct physical risk from a homeopathic pill is close to nil, and it would be dishonest to imply otherwise.

The risks are elsewhere.

Substitution and delay. This is the serious one, and it is the one the Australian review warned about explicitly: homeopathy should not be relied on for chronic or serious conditions, because people may put off treatment that would have worked. The harm is not the pill; it is the weeks that pass.

Specific situations where this has killed people. Homeopathic preparations have been sold for malaria prevention, which does not work and is lethal in a falciparum area — the real measures are under malaria and travel. The same applies to homeopathic alternatives to vaccination, and some practitioners do discourage vaccination, which is a reason to ask any practitioner directly what they advise.

Products that are not actually dilute. Preparations sold as homeopathic have occasionally contained material quantities of active substance through manufacturing failure, and children have been harmed. "It contains nothing, so it cannot hurt" relies on the dilution having been done properly.

The claim that it can be taken alongside anything without interaction. True of the preparation itself, and misleading in effect, because it is the sentence that makes stopping something else feel safe.

One further thing not to accept: the idea that fever and coughing are the body's way of expelling disease and should not be suppressed. Fever and cough are symptoms; treating them for comfort does not prolong an illness, and in the situations where a fever does need attention, what it needs is assessment.

Why people find it helps

Any honest account has to deal with the fact that a great many people report real benefit, and they are not fools or liars. Three things explain it without the remedies doing anything.

The consultation. A homeopathic appointment is typically long, unhurried and attentive, taking a full account of the person's life, sleep, mood, work and worries. That is a genuinely therapeutic experience, and it is precisely what people often do not get in a ten-minute appointment with a rushed clinician who does not look up. If homeopathy has an active ingredient, this is it.

Natural history. Most of what homeopathy is used for — colds, aches, skin complaints, low mood, digestive trouble, children's recurring illnesses — fluctuates and frequently resolves on its own. Anything taken during the bad patch gets the credit for the good patch that follows.

Placebo effects are real, particularly on symptoms like pain, nausea and fatigue. They do not shrink a tumour or clear an infection, but they genuinely change how people feel, and feeling better matters.

Which leads to the practical conclusion. The parts of a homeopathic consultation worth having — being listened to properly, being taken seriously, having the whole of one's life considered rather than one symptom — are worth asking for from anybody. The pill is not where they come from.

If someone is going to use it anyway

That is their decision to make, and it is a reasonable one for a self-limiting complaint where the alternative is also doing nothing much. In that case:

• Do not stop or reduce a prescribed medicine, and tell the GP what is being taken.
• Do not use it in place of vaccination, or in place of malaria prevention.
• Do not use it for anything serious, progressive, or not yet diagnosed. Get the diagnosis first.
• Take a child's or a baby's illness, and anything in pregnancy, to a doctor rather than a practitioner.
• Treat worsening symptoms as worsening symptoms, not as a sign of progress.
• Ask a practitioner outright what they think about vaccines, and what they would say if symptoms got worse. The answers are informative.

And for anyone who went to a homeopath because conventional care had not listened: that is a real problem with a real cause, and it is worth saying to the GP directly. It is a better complaint than most people realise.