Dr. Samuel Hahnemann talks of ‘idiosyncrasy’ in § 117, while describing proving of drug substances upon healthy individuals. In the § 116 he tells that

‘Some symptoms are produced by the medicines more frequently – that is to say, in many individuals, others more rarely or in few persons, some only in very few healthy individuals.’

This paragraph continues in § 117, thus

‘To the latter category belong the so called idiosyncrasies, by which are meant peculiar corporeal constitutions which, although otherwise healthy, posses a disposition to be brought into a more or less morbid state by certain things which seem to produce no impression and no change in many other individuals1.

Foot note(1): some few persons are apt to faint from the smell of roses and to fall into many other morbid, and some times dangerous states from partaking mussels, crabs or roe of barbel, from touching the leaves of some kinds of sumach etc.

But this inability to make an impression on every one is only apparent, for as two things are required for the production of these as well as all other morbid alteration in health of man
1. The inherent power of influencing substance

2. Capability of the vital force that animates the organism to be influence by it.
The obvious derangement of health in so called idiosyncrasies cannot be laid to the account of these peculiar constitutions alone, but they must also be ascribed to these things that produce them, in which must lie the power of making the same impression on all human bodies, yet in such manner that but a small number of healthy constitutions have a tendency to allow themselves to be brought into such a obvious morbid condition by them. That these agents do actually make this impression on every healthy body is shown by this, that when employed as remedies they render effectual homoeopathic service2

Foot note (2): Thus the Princess Maria Pophyroghnitha restored her brother, the Emperor Alexius, who suffered from faintings, by sprinkling him with rose water, in the presence of his aunt Eudoxia; and, Horstius saw great benefit from rose vinegar in cases of syncope.

to all sick persons for morbid symptoms similar to those they seem to be only capable of producing in so called idiosyncratic individuals’

MEANING OF THE TERM:
IDIO = self; SYN= with, along with; CRASY = make up, constitution
It is a habit or quality peculiar to any person or an abnormal susceptibility to some drug or protein peculiar to a person.

CONCEPT OF Dr JAMES TYLER KENT
He explains idiosyncrasy as an over sensitiveness to one thing or a few things.

It does not apply to the general susceptibility in feeble constitutions where patients are over susceptible and over impressed by simple annoyances. He compares it with the concept of the old school in which idiosyncrasies relate to certain patients who are known as oversensitive with every doctor. He sites the examples of over sensitiveness to opium and cinchona, due to their abuse in old school of medicine.

He elucidates that a homoeopath recognises wider ranges of susceptibility and classifies idiosyncrasy into

1. Acute idiosyncrasy from an acute miasm
2. Chronic idiosyncrasy from a chronic miasm.

He sites examples of idiosyncrasy – hay fever, rose cold, patient cannot bear smell of flowers, lavender flowers in particular etc.

He tells that if idiosyncrasy to a particular remedy is not present, the patient will not be susceptible enough to be cured. The state in which he becomes sensitive enough to a drug to cure him is very analogous to these idiosyncrasies.

Again classifies idiosyncrasy as
1. Acquired idiosyncrasy
2. In born idiosyncrasy

He tells that, the congenital forms and those coming from poisons are most difficult. Explains about Rhustox poisoning – being cured by c.m. or m.m. potency of same medicine. He tells that Psora is at the bottom of these idiosyncrasies. And patients getting up from typhoid fever have often idiosyncrasies.

There are certain cases where there is sensitiveness only when you go from the nutritive plane to the dynamic plane - example patient with craving for salt- no sensitiveness, when c.m. potency of salt administered there was violent aggravation. We step out of the nutritive plane into the plane of dynamics, the plane of disease cause and cure.

Example of children with calcium deficiency being cured with calcarea carb c.m. potency. Assimilation is improved.

Dr. Kent coins a new term – Homoeopathicity: - it is the relation between the homoeopathic remedy and the patient who has been cured. When the homoeopathic remedy has acted properly, when it has cured the patient, it has demonstrated that it was homoeopathically related to the case; so that the relation, when it was sustained, may be called the homoeopathicity.

He talks of poisons that take the nutritive plane and dynamic plane. A poison upon the nutritive plane is not usually very deep, while the poison taken upon the dynamic plane may last a life time. The miasms are of such a character. Substances that are inert and that are used as food in nutritive plane may become poisonous upon the dynamic plane. So that there is no substance that may not be a poison in higher and highest potencies.

We can say that, if there were no state of susceptibility no such condition as idiosyncrasy and no homoeopathy.

Observation 8 :(prognosis after observing the action of the remedy)

Patient inclined to by hysterical, overwrought and oversensitive to all things, prove every remedy they get. Such patients are said to be idiosyncratic. They are often incurable. You administer a dose of high potency and the patient goes on proving that remedy. Some of them are born with this sensitivity and they die with it. These individuals are very useful to the homoeopathic physicians.

CONCEPT OF STUART CLOSE
The explanation given by Dr. Stuart Close depicts ‘idiosyncrasy’ as a habit or quality of the organism peculiar to the individual. It is a peculiarity of the constitution, inherited or acquired, which makes the individual morbidly susceptible to some agent or influence which would not so affect others.

To the average physician idiosyncrasy is hypersensitiveness to the drugs ex – opium, quinine etc

Some patients manifest morbid susceptibility to agents and influences not classified as medicinal. For example some persons cannot eat apples, peaches, strawberries, fish, shell fish, onions, potatoes, milk, fats or butter. Idiosyncrasies of smell – to violets, lavender etc. sites example of a patient getting hay fever if she rides behind a horse, another patient developing violent trembling when coming near a cat. These cases are distinct from that of hysteria.

“The fundamental cause of every idiosyncrasy in morphological unbalance; that is, an organic state in which, through excess and defect in development there results excess and defect in function, with a corresponding degree of hyper-excitability or non-excitability.” (Rice)

For a homoeopathic prescriber, idiosyncrasy can often be the key to a difficult case. They can be viewed as modalities or even ranked as generals expressing the peculiarity of patients, example – aggravation from onions.

Idiosyncrasies can be inherited and acquired. Drug idiosyncrasies, both inherited and acquired, appear sometimes due to previous abuse of the drug. Some idiosyncrasy have their origin in Psoric constitution. Many persons who have been poisoned by a drug, after ward become hypersensitive towards that drug even in minute quantities – example Rhus or ivy poisoning.

In such persons disappearance of the original external manifestations is followed by setting up a constitutional susceptibility which renders then peculiarly vulnerable, not only to the particular drug concerned, but to the diseases to which that drug corresponds homeopathically. This view is based on direct observation, and is sustained by analogy with the well known serious results of the accidental or incidental disappearance or repercussion of external symptoms in acute in the acute eruptive diseases, such as measles and scarlet fever.

Where the initial attack is perfectly cured homoeopathically by internal medicines such results never follow. Investigation shows that some cases of inherited idiosyncrasy and morbid susceptibility to drugs are traceable to the abuse of those drugs by parents or ancestors. Especially in Mercury and Sulphur this phenomenon is observed.

CONCEPT OF J.H. ALLEN
He starts his lecture stating that we may have either a physical, mental or moral idiosyncrasy and it may enter into the desires, hopes, fears, cravings, longings, moods, and manners of life, or in any expression of life. It may show itself in any or one of the faculties of the brain. Examples – caution, oversensitiveness to smell of flowers, perfumes, gases, to light, noises, colours, animals, birds etc.

Often these peculiarities may be only temporary, as one witnesses it during pregnancy, puberty or in earlier child hood. Some patients are born with these diseases and shows them during certain sickness, such as prolonged fevers, gastro-intestinal disorders or others. Example craving of salt in tubercular constitutions or in patients with latent syphilitic taint

Idiosyncrasy is caused by certain kinds of food or drink – example urticaria from eating certain kind of sea food, shell fish or from eating certain vegetables or fruits, straw berries, asparagus, oatmeal. Honey frequently disturbs the kidneys and urinary tract. Nausea and vertigo while travelling, affected by atmospheric changes – storm, change in pressure etc.

Allen says that “often what are known as aggravations and ameliorations are due to idiosyncrasies. Patients suffering from idiosyncrasy cannot be said to be healthy human beings. They need anti miasmatic treatment; they need the similia that in their particular case removes or separates psora or tubercular element, or what ever may lie behind idiosyncrasy.

According to him idiosyncrasy is, in a sense, a bad habit of the organism or the mind. We see these mental or physical peculiarities cropping up in child hood or adolescence. Example craving for indigestible things – deficiency of calcium due to non assimiliation.

In pregnancy states, wishes and peculiar longings for salt pickles, sweets, stratches, acids, raw or uncooked food and grains, such as wheat, barely, rice, indigestibles like chalk, coal, earth and the limes etc. They long for travel, sight seeing, prefers solitude etc – their likes and dislikes seems to be magnified, all looming up to the latent miasm.

He further tells that idiosyncrasy and predisposition are so closely allied that we can scarcely separate them. To be predisposed to one thing is to have a weakness in that direction before-hand. Those patients who are so sensitively predisposed to every disease that comes along, that is, of a contagious nature, are usually of the tubercular type, or the miasm Psora, and syphilis (latent) is firmly implanted in that organism.

Occasionally we see patients who is not predisposed to natural disease states, but who is extremely sensitive and predisposed to artificial diseases, such as plant poisons which the rhus family is an example. So the author tells that an idiosyncrasy is behind the predisposition which intensifies the action of the poison. He strongly asserts that these constitutions have deep psoric taint or other miasmatic influences that make them sick. They are not healthy individuals.

He tells that ‘ an idiosyncrasy or a predisposition is then, as we have seen, a bad habit, and inhibitual condition formed in a life force, that has been under the promptings of some subversive force for years, yea, often through generations, of miasmatic action and the changes that are common to its subversion.

This phase of physiological perversion may be carried into moral sphere, as we see manifested in the desire to steal, to the use of alcoholic and other stimulants, tobacco etc. They may be born with just the right kind of toxic element in their system that will prompt the mind and propel everything in that direction.

CONCEPT OF J.N. KANJILAL
Idiosyncrasy means a peculiar blend of corporeal constitution which is otherwise completely healthy (functioning with balanced harmony) but is remarkably and sometimes harmfully hypersusceptible to some particular stimulus (environmental dietetic or medicinal) which are innocuous or even congenial to most others.

In drug proving we find that there are particular materials which are innocuous or even congenial to almost all organisms, but occasionally produce some peculiar form of derangement in sensation and function or structure of a particular organism, which is otherwise quite healthy. This inherent tendency in particular organism is generally found to be spontaneous, congenital and often even hereditary. So this tendency may be taken as belonging to the genetic sphere. This peculiar tendency manifested by very few healthy organisms on rare occasions is called idiosyncrasy,

The terms susceptibility and idiosyncrasy must also be clearly differentiated from hypersensitivity. Sensitivity is the basic and universal property of all living matter. When there occurs any excess of this faculty, irrespective to the nature of the stimuli or any definite and specific form of reaction, it is called hypersensitivity.

He differentiates idiosyncrasy from susceptibility

SUSCEPTIBILITY
1. Universal in all living organisms in various specific forms, which provide us with modalities and individualizing peculiarities of the case
2. May be hereditary or congenital or acquired as a result of some disease – natural or iatrogenic
3. May present various manifestations of deranged health
4. More easily reversible by appropriate treatment 1. Manifested by only few organisms with respect to a definitely specific exciting factor, with specific type of manifestations

IDIOSYNCRASY
2. Genetic in origin
3. May not present any other manifestation of deranged health
4. Not so easily amenable to treatment

References:
1. Organon of Medicine – Samuel Hahnemann translated by R.E.Dudgeon
2. Lectures on Homoeopathic Philosophy – J.T.Kent
3. Genius of Homoeopathy – Stuart Close
4. Writings on homoeopathy – J.N. Kanjilal
5. Notes on Miasm – J.H.Allen