“Do you know how your refrigerator works?”
This is the question my mentor, Dr. Stephen Messer, would ask any time a student challenged homeopathy because the mechanism of action couldn’t be described.
The answer was invariably, “I don’t know,” with a look of bewilderment. What does a refrigerator have to do with homeopathy?
“Do you know that it works, though?” Dr. Messer would follow up.
The answer would always be something along the lines of, “Because I put food in it and it gets cold.”
“Ah, I see,” Dr. Messer would reply. If you’ve listened to our podcast episode interviewing him, you can probably hear the calm tone he used when confronting a mental barrier. Those of us who had witnessed this before recognized that tone—it was the sound of him gently guiding someone toward curiosity rather than resistance.
Applying the Scientific Method in Homeopathy
“So,” he would continue, “you put food inside and something changes. You don’t know how the refrigerator works, but you see that when you use it, something changes, right?”
“Sure,” the student would reply, seeing where this was going.
“Well, we don’t know exactly how homeopathy works, but we know that if we give a remedy, nothing in the environment changes, and no other medicine is given, yet things change for the patient. Right?”
Depending on how far along the student was in clinical training, the answer would vary—but most would say yes.
“So, we use the scientific method, just as Samuel Hahnemann did, and we see that application of the law of similars leads to changes in the body. What we have to do is focus on how to use this law so that we, as clinicians, can achieve consistent results.”
Nanoparticles and New Research on the Mechanism of Action
Once I was a practicing clinician, I shifted how I answered this question with clients. Between the time I first heard Dr. Messer’s refrigerator analogy and when I graduated, new research on homeopathy emerged that brought us closer to understanding its mechanism of action.
This research identified the presence of nanoparticles in homeopathic remedies, once believed to be too dilute to contain any of the original substance. Additional studies showed these nanoparticles bind at the cellular level, producing adaptive physiological changes.
A recently published study titled Mapping the Theories and Models on the Mode of Action of Homeopathy: A Scoping Review found fourteen different proposed mechanisms of action, ranging from properties of water to concepts in quantum physics.
If you’d like to explore these studies, visit the Homeopathic Research Institute (HRI) website. (Be sure to sign up for their newsletter for updates.) We also had the pleasure of interviewing Rachel Roberts, HRI’s Chief Executive, on our podcast—an excellent introduction to the world of rigorous homeopathic research.
Revisiting Hahnemann’s Explanation: The Primary and Secondary Action
Over time, my own explanation of how homeopathy works has evolved. While I value modern research, I still lean on Hahnemann’s wisdom in The Organon of Medicine.
In it, he argues that physicians should focus on helping people heal rather than obsessing over mechanisms they cannot yet explain. Still, he offers a theory: all substances have a primary and secondary action.
For example, caffeine’s primary action is stimulating—it increases alertness, restlessness, and heart rate. But the secondary action belongs to the body itself: once the stimulation fades, we feel tired or experience the “caffeine crash.”
Homeopathy works by harnessing these secondary effects. When we give something similar to the symptoms being experienced, the body’s secondary action produces the opposite effect—healing. The ultra-dilute preparations minimize the primary effect, allowing the secondary healing response to dominate.
Simple Principles, Evolving Understanding
This explanation, though simple, matches what we observe in practice. Hahnemann was writing about caffeine and bacteria long before either was chemically identified. And even today, modern medicine doesn’t fully understand how common drugs like Tylenol or lithium work.
So while my curiosity as a scientist pushes me to keep learning about the mechanism of action in homeopathy, I still find that Hahnemann’s principle—the law of similars and the secondary action of substances—remains both elegant and practical.
