Hormesis is the idea that some substances may have opposite effects, based on the dosage. While a large dose of a certain product may be harmful, a low dose may actually be beneficial.

Professor Edward Calabrese, toxicology expert at the University of Massachusetts, describes hormesis as “a dose-response relationship phenomenon characterized by low-dose stimulation and high-dose inhibition”.[1]

Vitamins are a very good example of hormetic substances. Small doses of vitamins are not just beneficial, they are vital to a good health and to life. Many people think that this means that swallowing more (mega-doses) will be even better. They turn out to be sorely mistaken and high doses are demonstrated to be indeed toxic, to the point of killing the patient in some cases.

Dr Peter Fisher, Director of the Royal London Homeopathic Hospital and homoeopath to the British royal family, is often heard proposing hormesis as an explanation of the like-cures-like principle of homoeopathy. This is blatantly wrong and it is rather embarrassing that he even proposes it.

This position is an over-extrapolation of hormesis: it is not because the effect is real in some cases, that it will be like this in all cases.

The hormesis hypothesis is further invalidated by the fact that it does not make much sense that a highly diluted product would cause certain symptoms in healthy people while actually removing those same symptoms in sick people. This is actually demonstrably wrong. For example, a lack of vitamin C can cause bleeding gums and can make teeth fall out. Administering vitamin C will solve these problems, but it will most definitely not cause these very problems in healthy people.

Hormesis can also be easily dismissed as an explanation for the homoeopathic like-cures-like principle in the most evident of cases. It is hard to accept that insomnia caused by coffee would be solved by administering highly diluted coffee. Yet, according to the like-cures-like principle, this should work perfectly, since the symptoms being addressed are not just similar, but rather identical to the ones being caused by coffee.

It could be argued by homoeopaths that this is not an example of homoeopathy however, but rather an example of isopathy. They would be correct, and Samuel Hahnemann -the founder of homoeopathy- would probably turn around in his grave when he reads this. Not that it matters much in practice. Homoeopathy doesn’t work anyway.

And then of course, there is the most devastating reason of all: 30C, the standard (but not only) dilution in homoeopathy, is such that -as a rule- not a single molecule of the substance is still present in the product. For hormesis to be responsible for the efficacy of homoeopathy, one molecule at least should still be present in the product.