Homeopathy is a great example of a parallel medical world with a well-defined origin that predates science-based medicine. It is very popular world-wide and has gained in popularity in the United States. It has become big business. Singh and Ernst report in their book, Trick or Treatment, that sales of homeopathic products in the U.S. in the year 2000 reached $1.5 billion. The combined sales in other countries are much higher.

It began in the late 1700's with a German physician named Samuel Hahnemann. He was well respected and regarded in the fields of medicine and chemistry. During his day, most medical practices were unsupported by science. Indeed, the randomized controlled trial was not a part of medical science yet. Doctors often did more harm than good. The ancient practice of bloodletting was very popular (and in retrospect, very deadly). Hahnemann developed a system of medicine that was actually better than 'mainstream' medicine at the time. His system has become known as 'homeopathy'. He wished to harness the body's 'vital force' to promote self-healing. As he did not actively harm his patients by bleeding or poisoning them, his patients seemed to fare better.

Since his time, much has been learned about chemistry, biology and physics. Hahnemann's ideas contradict our current established scientific knowledge that was not present in his day. Homeopathy should be an interesting footnote in the history of medicine, marking one of the many false starts that will inevitably be present with any branch of science. Instead, it is still practiced today by believers and science denialists in a quasi-reality world supported by cognitive dissonance, confirmation bias, the regressive fallacy, the placebo effect and many more. Its claims are falsifiable, which makes homeopathy eligible for scientific criticism.

The Law of Similars

Hahnemann's idea was that things that could produce the same symptoms of a condition, would cure the condition. This has become known as 'like cures like' or the 'Law of Similars'. For instance, Allium cepa comes from the red onion. Onions are associated with eye irritation and tearing. Pollen allergies can also lead to eye irritation and tearing. Therefore, according to the Law of Similars, Allium cepa should cure pollen-related allergic conjunctivitis.


Finding the right 'cure' for different conditions depended on the symptoms of the condition. They are found and categorized through a process called 'proving'. Here, different substances are supposedly given to healthy subjects to see what symptoms they produce. Those substances then are considered to be possible cures for conditions that present with similar symptoms. With this in mind, one might consider sugar to be a cure for diabetes.

The Law of Infinitesimals

However, Hahnemann did not give the cures directly to patients (one could speculate that doing so would likely increase the very symptoms that Hahnemann wished to cure). The next step in the process involves a series of dilutions and succussions (ritualistic shaking). He felt that a remedy would become more potent the more times it is diluted in water. This is known as the 'Law of Infinitesimals'.

First, the cure is prepared in a water mixture called the 'mother tincture'. Then a small amount is dropped in another container of water and vigorously shaken. This process is repeated over and over, with each container containing a more dilute amount of the original. When finally done, the final, ultra-dilute 'solution' is ready for medicinal use. These solutions can be given to patients directly on the tongue or by putting them on a sugar pill.

Homeopathy In Practice

The practitioner ('homeopath') takes a great deal of time interviewing the patient, learning about all of the symptoms that are causing problems. The symptoms are then 'treated' with the appropriate homeopathic preparation. Sometimes, cures are chosen through other methods, such as dowsing with pendulums. Most of the homeopathic preparations begin with solutions of some form of botanical / plant source. This mistakenly leads people to think that homeopathy is synonymous with 'herbal medicine'. It is not. Herbal medicine does not dilute its products until they are no longer present, as we shall see is essential to the principles of homeopathy.

Today, homeopathy is practiced in offices similar to mainstream doctors' offices. The preparations are often sold directly to patients from the office. Homeopathic sugar pills are also manufactured on a large scale and sold at large chain retail pharmacies.

In Great Britain, there are whole institutions that call themselves homeopathic hospitals. There are four homeopathic hospitals in the UK, based in London, Bristol, Liverpool and Glasgow.

Dilution and Avogadro's Number

Let's take a closer look at the dilution process. Remember, the dilution process is key in the world of Homeopathy. First, we should remember from high school chemistry class that Avogadro found that there are (roughly) 6 x 1023 (that is a 6 followed by 23 zeros, or 600,000,000,000,000,000,000,000) atoms of carbon in 12 grams of carbon. Since carbon's atomic number is 12, he used this as a reference quantity called a 'mole'. Thus, there are 6 x 1023 'things' in a 'mole' (just as there are 12 'things' in a 'dozen'). This is a very convenient number for chemists because they can measure substances in grams and then figure out how many moles of that substance are present. This tells them how many atoms or molecules are present. Typically, concentrations of solutions in chemistry are given as 'moles per liter'. As an everyday example, Coca-Cola is approximately a 1 'mole per liter' solution of sugar. Thus, it has about 6 x 1023 molecules of sugar per liter (this is not exact, but workable for our example).

Now, let's look at the system of dilution that homeopaths actually use. It is customary to use dilutions by a factor or 1/10 or 1/100.

A 1/10 dilution means that you take 1 ml of the mother tincture and put it in 9 ml of water (and then shake it up in a ritualistic fashion). If you do this once, then it is called a 1X solution. If you take 1 ml of this and put it in 9 ml of water (again shaking / succussing), then you have a 2X solution. Do this 5 times for a 5X, 10 times for a 10X. Remember, in the world of Homeopathy, the more dilute a solution is, the more potent it becomes as a treatment.

A 1/100 dilution means that you take 1 ml of the mother tincture and add it to 99 cc of water (then shake / succuss). This is called a 1C solution. This is already 10 times more dilute than a 1X solution. Do this twice for a 2C, 10 times for a 10C. Today's homeopathic products often claim dilutions or 50C, 100C or higher!

Now, let's consider Avogadro's number again. Let's also consider (just for fun), making a homeopathic cure for diabetes using the sugar solution of Coca-Cola.

If we start with 100 ml of Coke, we would then take 1 ml and drop it in 99 ml of water (and shake). To make a 15C solution, we would repeat this 15 times. Now, each time we do this, each step essentially gives us a solution that is 100 times as dilute as the previous one. That is, if we start with 6 x 1023 sugar molecules, the first dilution would have about 6 x 1021 molecules. Each dilution would decrease the exponent by 2. After 10 dilutions, we could expect 6 x 103 sugar molecules (or 6000), After 11 dilutions, we could expect 60 molecules. After 12 dilutions, there is only a chance of having even one molecule left. After 15 dilutions (15C), we would expect no molecules at all. The statistical chances of retaining even one molecule of a substance after 13 or 14 dilutions is very small. Our final solution is just water.

An 18th century Russian homeopath named Semen Korsakov came up with a different way to make the preparations. Instead of transferring 1 ml of a solution to another container of water, Korsakov simply emptied the container and then filled it again (followed by shaking). He would repeat this over and over, thereby only needing one container. The idea was that a small amount of the previous solution would adhere to the container walls after emptying, such that filling it again would produce about a 1/100 dilution.

Today, commercial homeopathy is produced this way (supposedly). In fact, once the final 'dilution' is done (sometimes 200C or higher!), the solution is sprayed onto sugar pills. However, because pills must be produced on a commercial scale, only a small amount of pills are initially made this way. These initial pills are used to 'charge' other pills with their 'memory' of the initial substance. A small amount of sprayed pills are added to a large container of 'uncharged' sugar pills, and the container is shaken, thus transferring the energy of the sprayed pills to the others.

A great deal of time is spent commercially preparing mother tinctures from various plants. A video describes the process, but quickly glosses over the part about diluting the water until nothing is left and spraying the water onto sugar pills.

Commercial products that are listed as 20C or more essentially cannot have any trace of the original substance. Any sugar pill sprayed with this water cannot have any of the 'active' ingredient. A common homeopathic product, arnica ('wolf's bane), is said to help with bruising. It is sold at dilutions of 1,000C ! It is the ultimate placebo in that these preparations would have you believe that there are active ingredients, but per their own labels tell you that there is nothing in them.


Homeopaths are often confronted with the fact that their treatments have nothing in them. To account for this, many now state that the water has some kind of memory of the original substance. Thus, the water is 'charged' with this memory and becomes a powerful treatment tool. Some use the appeal to quantum physics logical fallacy to explain how sciency sounding things like quantum states and 'nano-bubbles' are responsible for the water's memory. Others fracture Einstein's E=mc2 to explain it. Technobabble is a hallmark of pseudoscience.

The Evidence for Homeopathy?

Even before randomized controlled trials are considered, the science-based medicine proponent should recognize that the concept has little to no plausibility.

Homeopathy would require fundamental changes to the laws of physics and chemistry in order to be true. It would require changes to all that we know about disease. For instance it would require that things that make you sneeze can cure allergies, and then it would require that giving water without a trace of the substances would work (the less the better).

Remember Baye's Theorem:

P(H/D) = P(D/H) x P(H)


where P(H/D) is the probability of a hypothesis being true in light of the most current data,

P(H) is the "prior probability" of the hypothesis being true given what we knew about it prior to new data,

And P(D/H) is the probability of data being true given the hypothesis (the "strength" of the new data).

In other words, before a new experiment is done, the probability is P(H). After an experiment is done, the probability is P(H/D).

If the P(H) is very low, it would take an extraordinary amount of new data from high quality studies to overcome the low prior probability. Extraordinary claims require extraordinary evidence.

From a Bayesian perspective, the prior probability for Homeopathy approaches zero. Therefore, for almost any strength of new data from clinical trials, the probability that homeopathy works, would still be close to zero. It would take mountains of consistent and unambiguously positive studies to bring homeopathy's probability up to reasonable.

Science-based medicine (SBM) proponents call for a Bayesian approach to medical science. Our system seems to be dominated by proponents of evidence-based medicine (EBM), which is good, but undervalues prior probabilities. EBM seems to focus on new data, despite prior probabilities. In EBM, data from clinical trials and meta-analysis seem to trump basic science, even when the new data is relatively weak and the basic science is strong. SBM can dismiss Homeopathy from a Bayesian perspective by recognizing that its prior probability is zero. But, let's consider Homeopathy just in light of clinical trials (EBM).

So, what does the clinical science have to say? There have been many studies to evaluate the effectiveness of specific homeopathic treatments for specific problems. Cochrane has several systematic reviews and meta-analysis of these studies. Below are some examples.

For Attention Deficit Disorder, Cochrane states, "Overall the results of this review found no evidence of effectiveness for homeopathy for the global symptoms, core symptoms or related outcomes of attention deficit/hyperactivity disorder."

For chronic asthma, Cochrane states, "...no strong evidence existed that usual forms of homeopathy for asthma are effective." And that, "Until stronger evidence exists for the use of homeopathy in the treatment of asthma, we are unable to make recommendations about homeopathic treatment."

For dementia, Cochrane states, "The researchers did not find any good quality trials and so cannot say whether it is or is not effective for treating this condition. As no information is available on how much homeopathy is used for dementia, it is difficult to say whether it is important to conduct more trials."

For insomnia, Sleep Medicine Reviews concludes, "The limited evidence available does not demonstrate a statistically significant effect of homeopathic medicines for insomnia treatment."

For 'fibromyalgia', Clinical Rheumatology concludes, "...the effectiveness of homeoopathy as a symptomatic treatment for FM remains unproven."

The product 'oscillococcinum' is sold commercially in major pharmacy chains. It is literally made from nothing and then diluted! Clearly, the prior plausibility approaches zero, yet it has been studied. Cochrane reviewed it, but then withdrew the review. It stated, "Though promising, the data were not strong enough to make a general recommendation to use Oscillococcinum for first-line treatment of influenza and influenza-like syndromes. Further research is warranted but the required sample sizes are large. Current evidence does not support a preventative effect of Oscillococcinum-like homeopathic medicines in influenza and influenza-like syndromes."

The above clearly demonstrates the difference between EBM and SBM. Near zero plausibility claims are tested anyway with low-quality studies and the near null results are given a flavor of legitimacy. As is common in such cases, more studies are called for. When higher quality studies show no effect, the topics are still left as 'inconclusive' (see The Face on Mars Effect).

Many seek homeopathic care for anxiety and depression. Very few studies have been done that were properly controlled. Thus, even the journal, Homeopathy concludes, "On the basis of this review it is not possible to draw firm conclusions on the efficacy or effectiveness of homeopathy for anxiety." For anxiety, the conclusion was, "A comprehensive search for published and unpublished studies has demonstrated that the evidence for the effectiveness of homeopathy in depression is limited due to lack of clinical trials of high quality."

The examples can go on, but one starts to get the picture. In 2010, Edzard Ernst conducted a review of all of the systematic reviews of homeopathy in the Cochrane database. His conclusion was, "The findings of currently available Cochrane reviews of studies of homeopathy do not show that homeopathic medicines have effects beyond placebo."

In 2015, the largest ever systematic review of systematic reviews of homeopathy was published by Australia's National Health and Medical Research Council. 57 systematic reviews were identified that contained 176 individual studies. Over 1,800 studies were considered, most of which were very poor in quality due to lack of controls or other violations of scientific procedure. The conclusion of the review states:

"Based on the assessment of the evidence of effectiveness of homeopathy, NHMRC concludes that there are no health conditions for which there is reliable evidence that homeopathy is effective. Homeopathy should not be used to treat health conditions that are chronic, serious, or could become serious. People who choose homeopathy may put their health at risk if they reject or delay treatments for which there is good evidence for safety and effectiveness. "

Trying to Have it Both Ways

There have been a handful of small, mostly flawed studies that claim an effect over placebo. However, when study design is improved and the controls are tightened, the effect always shrinks and vanishes. Remember, in order to overcome the huge hurdle of implausibility, studies should be overwhelmingly positive in order for us to consider the claim. Defenders of homeopathy proudly point to these earlier, small studies to prop up their claim that homeopathy works. It would appear that they place at least some value on science. However, when the science is negative, proponents then reject science as unreliable or not applicable to their field (see Special Pleading and You Can't Have it Both Ways).

In 2005, a BBC News article reported on the lack of scientific support for Homeopathy.

"A spokeswoman from the Society of Homoeopaths said: "Many previous studies have demonstrated that homeopathy has an effect over and above placebo."

"It has been established beyond doubt and accepted by many researchers, that the placebo-controlled randomised controlled trial is not a fitting research tool with which to test homeopathy."

Remember the thesis.

** It is logically contradictory - and therefore forbidden - to embrace science and logic when they support an idea, but then to reject them when they do not.

What's the Harm?

Although no direct harm can come from ingesting small amounts of water or sugar pills, a great deal of harm can result from favoring sugar pills over potentially life-saving treatment. Patients with AIDS and cancer may put their trust in water and sugar pills instead of anti-retrovirals, surgery or chemotherapy. Homeopathic malaria prophylaxis cannot protect people from malaria. And of course, vaccine refusal in favor of homeopathic preventative measures can have tragic results.

Lesson to be Learned?

There is a good lesson for skeptical doctors to learn. Research has shown that the perceived benefits from encounters with homeopaths correlate with the intimate quality of the consultations, not with the labels on the bottle of water that are sold. The consultation visit times are typically much longer than mainstream doctor's office visits. Homeopaths typically probe deeply into patients' intimate, personal histories; their likes, dislikes, feelings about family, work and themselves, etc. Talking about personal feelings with someone who appears to care can be very rewarding. Homeopaths tell their patients that they individualize treatment plans just for them. Coupled with a self-selected patient population with a baseline belief in homeopathy, the personal encounter with a homeopath can make a patient feel better. It does not, however, appear to cure disease.

When one is deeply invested in a pseudoscience such as homeopathy, one cannot see the world as science presents it. Just as Neo could not see the 'Matrix' for what it was just by being told, neither can anyone in the homeopathic world see the real world just by being told. Homeopaths and their defenders took the blue pill.

And there was nothing in it.

John Byrne, M.D.

(back to Pseudoscience in Healthcare)

References and Links

"Trick or Treatment: The Undeniable Facts about Alternative ..."


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"Samuel Hahnemann - Wikipedia, the free encyclopedia." 2003.


"Semen Korsakov - Wikipedia, the free encyclopedia." 2008.


Heirs, M. "Homeopathy for ADHD | Cochrane Summaries." 2009.


McCarney, RW. "Homeopathy for chronic asthma | Cochrane Summaries." 2008.


McCarney, RW. "No evidence that homeopathy is effective in treating dementia ..." 2009.


Pilkington, Karen et al. "Homeopathy for depression: a systematic review of the research evidence."

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Pilkington, Karen et al. "Homeopathy for anxiety and anxiety disorders: a systematic review of the research."

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Perry, Rachel, Rohini Terry, and Edzard Ernst. "A systematic review of homoeopathy for the treatment of fibromyalgia."

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