In the simplest sense, homoeopathic remedies are unscientific because there is no evidence from well designed, controlled clinical trials that homoeopathic remedies perform better than placebo. They cannot thus be regarded as evidence-based treatments.
Moreover, homoeopathic remedies are unscientific because the supposedly chemical and physiological principles of homoeopathy have no grounding in science.
In other words, homoeopathic remedies not only don’t work, but as far as current state of scientific knowledge goes, cannot work. There is no recognised scientific mechanism that could explain their working.
Homoeopathy is an alternative therapy based on the principle of “like treats like”. This means that a substance that in greater concentrations would cause particular symptoms in healthy people is used, diluted, to treat the same symptoms in a sick person.
There is no evidence whatsoever for this principle to be true. The same symptom can be caused by multiple causes, for example vomiting can be caused by chemical poisoning, bacterial or parasitic infection, motion sickness, pregnancy hormones or stress. Anti-emetic drug might alleviate the symptom, but the only way to actually remove it is to deal with the underlying cause.
But the “like-with-like” principle is only the beginning. Homoeopathic remedies are prepared by a serial dilution of the active ingredient. This is because the original creator of homoeopathy, Hahnemann, found that administering the active ingredient undiluted caused the symptoms to worsen rather then improve. Homoeopathic dilutions are huge, to the degree that the final remedy is extremely unlikely to contain even a single molecule of the active ingredient. Homoeopathic remedies are marked by their “potency”, or dilution factor. The most commonly used scale is a C scale, in which the substance is diluted by the factor of 100 at each stage. Thus, 1C dilution would have one part of active substance in 100 parts of the medium (water). 3C dilution will have 1 part of the active substance in a million parts of the medium.
To make it more clear, a 12C solution will equal dissolving one pinch of salt in the whole of the Atlantic Oceans, while 13C solution would mean diluting less than a drop of the active substance in all the water that is present on Earth.
The dilution most commonly advised by Hahnemann is 60C: 60 dilutions, each by a factor of 100, resulting in a final dilution by a factor of 10 to the power of -60. Many modern homoeopathic remedies are of 30C potency. 1 ml of a solution which has gone through a 30C dilution can be thought to be equivalent to 1ml (one fifth of the teaspoon) of the active substance diluted into a cube of water measuring over 100 light years per side.
Most homoeopathic remedies are extremely unlikely to contain a single molecule of the original active ingredients.
A key stage in the production of homoeopathic remedies is “succussion” which constitutes of shaking, or rather forcefully striking a container with the dilution on a hard surface (a horse-hair filled bench). This is supposed to increases the strength of the remedy and is thus called “potentization”. Homoeopaths believe that more diluted remedies are more potent. This flies against all scientific ideas and means that remedies containing no active ingredients whatsoever are considered to be the strongest.
In Hahnemann’s time, the molecular nature of substances was unknown and thus belief in the possibility of almost infinite dilutions which still retained some of the active ingredient was not unreasonable. Development of modern, scientific chemistry caused a major problem for the homoeopaths, who needed to come up with some mechanism that explained how an entirely inert substance with not a single molecule of the original active ingredient could possibly have any therapeutic effect.
The explanation favoured currently is one that relies on so called “molecular memory” of water. According to homoeopaths, the dilutant (water) retains some form of “memory” of substances that were once dissolved in it. The concept itself is considered pseudo-scientific, and it is now recognised that water essentially loses any kind of memory of diluted substances within time shorter than a millionth of a second within fifty millionths of a nanosecond. A minute’s thought will show how absurd the concept is: all water present on earth has been through the whole water cycle (including bodies of many animals) several times, and if a permanent molecular memory was real, all water would carry memory of hundreds or thousands substances that had been once dissolved in it!
Homoeopaths claim that the “succussion” (shaking energetically, or rather striking against that horse-hair filled bench) is necessary for the water memory to occur: but there is no evidence that it has any effect.
Homoeopathy is based on unscientific principles, dating to 18th century theories about “miasmas” and “vital forces”. There is no scientific evidence as to homoeopathic treatments being clinically more effective than placebo, and its supposed mechanism is unscientific too. Homoeopathy does not work and it has no right to work in the light of our current understanding of how the natural world works.
Source of examples: http://en.wikipedia.org/wiki/Homeopathic_dilutions