A little background on homeopathy. The following is not a rant. It is an outline of useful facts, most of which are cited and all of which are verifiable.
What is homeopathy?
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Classical homeopathy originated in the 19th century with Samuel Hahnemann (1755-1843) as an alternative to the standard medical practices of the day, such as phlebotomy or bloodletting. Hahnemann's theories were based on metaphysical energies rather than on biology, anatomy, chemistry, etc.
Classical homeopathy is generally defined as a system of medical treatment based on the use of infinitesimal amounts of substances that in larger doses produce effects similar to those of the disease being treated. For example, the homeopathic remedy for sleeplessness is a highly diluted dose of caffeine. Hahnemann believed that very small doses of a substance could have very powerful reverse healing effects because their potency could be affected by vigorous and methodical shaking (succussion).
So in other words, if you put a tiny amount of some ingredient in water, then shake it, then dilute it, then shake it more, then dilute it more, eventually you'll have an effective medicine.
Homeopathic dilutions
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Homeopathic dilutions are indicated by letters like X or C. "X" means dilute 10 to 1. So a dilution of 6X means do a 1 in 10 dilution six times. Or, in other words, 1 part ingredient, 1,000,000 parts water (six zeros). "C" means dilute 100 times. So a 6C dilution means 1 part ingredient, 1,000,000,000,000 parts water. You can find many homeopathic remedies available with 30C dilutions - you do the math. And the totally ridiculous bit of advertising - the bigger the dilution, the "stronger" the medication.
Here is a useful table of homeopathic "potentencies" and their dilution rates (0.1ml of original ingredient):
6C = 4 Olympic class swimming-pools.
13C = 3/4 of all Earth's oceans.
16C = Sphere of water the size of Earth.
19C= 10 Spheres with same diameter as our Solar System
22C = 1 cubic light-year
26C = 1 Sphere with same diameter as the Milky Way
Another example, the very popular homeopathic remedy Oscillococcinum 200C is made with a 1 in 100 dilution performed 200 times. That's 1 part ingredient in 1 followed by 400 zeros parts water, then sprinkled on a sugar pill. Now, physics will tell you that there is not a single molecule of duck liver on your sugar pill.
In summary, the homeopaths are water or a sugar pill on which water has been sprinkled.
Hahnemann came up with his ideas before we knew what molecules were. So when molecular theory came along and proved that many homeopathic remedies didn't have even a single molecule of the original substance, homeopathy proponents like Jacques Benveniste tried to prove that water "remembered" the original ingredient. (1) They never explained how the water "remembered" the homeopathic ingredient but didn't "remember" the copper pipes, glass jars, or fish poop from the lake it came from. (2) Benveniste was completely discredited when it turned out his lab technicians were altering data so that their boss would have positive results.
http://br.geocities.com/criticandokardec/benveniste02.pdf
Here is a very handy, professional video on homeopathy:
http://www.youtube.com/watch?v=jYqQ_n2vOOI
Do Homeopathic Remedies work?
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Because it has marketing appeal, "Homeopathic" is used as a label on many things, including soothing creams and herbal remedies that are NOT classic homeopathic dilutions. An herbal remedy may work just fine, but it is just like any drug, and should come with all the same testing and warnings as any drug. However, the classic homeopathic dilution liquids and pills do NOT work better than water or sugar pills.
1) Large scale, well-designed studies of homeopathic dilutions find they work no better than placebo. (But don't underestimate the power of a well-delivered placebo to cure somebody's complaint. People who "believe" they feel better usually DO feel better. Just don't try to use a placebo for cancer or malaria or AIDS, etc.)
2) There is a million dollar prize available from JREF for anyone who can show, under reasonable scientific controls, that homeopathic dilutions work better than placebo. The prize has been available for over a decade, and nobody has claimed it. Here is an example of a failed attempt: http://www.abc.net.au/catalyst/stories/s827502.htm
3) No homeopathic practitioner (or anyone else) can tell the difference between a vial of homeopathic dilution and plain water.
http://www.bbc.co.uk/science/horizon/2002/homeopathy.shtml
4) James ***** regularly demonstrates homeopathic remedies do nothing by taking an entire bottle of Calms Forte - a homeopathic sleep aid. Even though the box says "warning, don't exceed recommended dosage", the entire bottle of pills has no effect on ***** or on anyone else.
http://video.google.com/videoplay?docid=2785985155605802136
And on Jan 30, 2010, 400 people intentionally took overdoses of homeopathic medicines to prove they are worthless. The protesters suffered no ill effects other than a rush from sugar pills.
http://www.1023.org.uk/the-1023-overdose-event.php
5) A comprehensive British government study just concluded that homeopathy is nothing but sugar pills and water, and that the National Health Service should stop paying for it.
http://www.publications.parliament.uk/pa/cm200910/cmselect/cmsctech/45/4504.htm#a18
6) The US National Center for Complimentary and Alternative medicine has stopped funding any research on homeopathy. Even the NCCAM, which happily funds research on other dubious treatments, has determined that homeopathy is a waste of research dollars.
In short, homeopathic pills/dilutions don't work any better than sugar pills.
Why does the FDA allow ineffective "medicines" to be sold?
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Homeopathy websites will talk about homeopathy's great safety record. That's true - water and sugar are pretty safe. But are they effective?
Because of their long use in the United States, the U.S. Congress passed a law in 1938 declaring that homeopathic remedies are to be regulated by the FDA in the same manner as nonprescription, over-the-counter (OTC) drugs, which means that they can be purchased without a physician's prescription. Today, although conventional prescription drugs and new OTC drugs must undergo thorough testing and review by the FDA for safety and effectiveness before they can be sold, this requirement does not apply to homeopathic remedies. In other words, the FDA gave anything with the words "homeopathic" an exemption from the requirement to demonstrate that they're effective.
http://www.homeowatch.org/history/reghx.html
This is important: as long as something appears in the "Homeopathic Pharmacopeia of the United States", the FDA does not require proof that it is effective.
Most people know that the herbal remedy St. Johns Wort can reduce the effectiveness of birth control pills. However, unlike herbal remedies, there are no "drug interaction" warnings for homeopathic remedies. Why are there no drug interaction warnings? Because homeopathic remedies don't do anything.
Conclusion:
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If you can be cured by placebo, then by all means, give money to the imaginative people who dream up all the different homeopathic remedies. But you should look at the price on the box and ask yourself: Is this a lot to pay for sugar pills and water?