Allopathic medicine
Some medical dictionaries define the term Allopathy or Allopathic medicine as the treatment of disease using conventional evidence-based medical therapies, as opposed to the use of alternative medical or non-conventional therapies.
The term allopathic, an adjective, is used in medicine to distinguish one form of medical practice, medical tradition, or medical profession from another. The term was coined by the founder of homeopathic medicine, and was used through the 19th Century as a derogatory term for the practitioners of orthodox medicine.  The meaning and controversy surrounding the term can be traced to its original usage during a heated 19th-century debate between practitioners of homeopathy, and those they derisively referred to as "allopaths."
Today, the term "allopathic medicine" has been revived and its use as a synonym for mainstream medicine has become commmon.  In recent years, many M.D.s accept this designation, i.e. an "allopathic physician."   In the United States, "allopathic" is used by the American Medical Association, the National Residency Matching Program, and the Association of American Medical Colleges. These organizations use the term to distinguish the schools and residency training programs which they govern from the osteopathic medical schools and programs, accredited by the American Osteopathic Association.

# Origin
The term allopathy was coined by the founder of homeopathy, Samuel Hahnemann, to differentiate homeopathic practices from conventional medicine, based on the types of treatments used.
Hahnemann used allopathy to refer to what he saw as a system of medicine that combats disease by using remedies that produce effects in a healthy subject that are different (hence Greek root allo- "different") from the effects produced by the disease to be treated. He claimed that his theory of homeopathy, which attempts to mimic the disease symptoms (hence homeo-, "the same"), was a more effective and humane alternative.

# History
As used by homeopaths, the term allopathy has always referred to a principle of curing disease by administering substances that produce the opposite effect of the disease when given to a healthy human. For example, an allopathic treatment for fever is a drug which reduces the fever.  A homeopathic treatment for fever, by contrast, is one that induces fever in a healthy person.  Hahnemann used this term to distinguish medicine as practiced in his time from his use of infinitesimally small doses of substances to treat the spiritual causes of illness.
William Jarvis claims that "although many modern therapies can be construed to conform to an allopathic rationale (eg, using a laxative to relieve constipation), standard medicine has never paid allegiance to an allopathic principle" and that in the nineteenth century, the label "allopath" was "considered highly derisive by regular medicine."
James C. Whorton also discusses this historical pejorative usage:
One form of verbal warfare used in retaliation by irregulars was the word "allopathy." ....... "Allopathy" and "allopathic" were liberally employed as pejoratives by all irregular physicians of the nineteenth century, and the terms were considered highly offensive by those at whom they were directed. The generally uncomplaining acceptance of "allopathic medicine" by today's MDs is an indication of both a lack of awareness of the term's historical use and the recent thawing of relations between irregulars and allopaths.
The Companion Encyclopedia of the History of Medicine states that "Hahnemann gave an all-embracing name to regular practice, calling it 'allopathy'. This term, however imprecise, was employed by his followers or other unorthodox movements to identify the prevailing methods as constituting nothing more than a competing 'school' of medicine, however dominant in terms of number of practitioner proponents and patients."  In the nineteenth century, some pharmacies labelled their products with the terms allopathic or homeopathic.
Contrary to the present usage, Hahnemann reserved the term of "allopathic" medicine to the practice of treating diseases by means of drugs inducing symptoms unrelated (i.e. neither similar nor opposite) to those of the disease. He called instead "enantiopathic" or "antipathic" the practice of treating diseases by means of drugs producing symptoms opposite to those of the patient (e.g. see Organon, VI edition, paragraphs 54-56). After Hahnemann's death the term "enantiopathy" fell in disuse and the two concepts of allopathy and enantiopathy have been more or less unified. Both, however, indicate what Hahnemann thought about contemporary conventional medicine, rather than the current ideas of his colleagues. Conventional physicians had never assumed that the therapeutic effects of drugs were necessarily related to the symptoms they caused in the healthy: e.g. James Lind in 1747 systematically tested several common substances and foods for their effect on scurvy and discovered that lemon juice was specifically active; he clearly did not select lemon juice because it caused symptoms in the healthy man, either similar or opposite to those of scurvy.
Practitioners of alternative medicine have used the term "allopathic medicine" to refer to the practice of conventional medicine in both Europe and the United States since the 19th century.  In the U.S., this was also referred to as regular medicine  that is, medicine that was practiced by the regulars.  The  practice of "conventional" medicine in both Europe and America during the 19th century is sometimes referred to as the age of 'heroic medicine' (because of the 'heroic' measures such as bleeding and purging).

# Current usage of term
There are several definitions given for allopathic medicine, with different connotations.

## Modern, regular medicine
Some dictionaries define allopathic medicine as conventional medicine. Stedman's Illustrated Medical Dictionary defines it as "egular medicine, the traditional form of medical practice", contrasting it with "homeopathy". The Oxford English Dictionary presents a similar formulation: "the present prevailing system of medicine", as one of its definitions of the term..
Some authors within the field of alternative medicine suggest the meaning of allopathic medicine is derived from a literal translation of its word parts, from the Greek allo meaning other and pathos meaning suffering.  Homeopaths gave their opponents this label in reference to the "other suffering" or the adverse side effects caused by the drugs their contemporaries prescribed.

## Homeopathy and heteropathy
Steadman's Medical Dictionary calls heteropathy a "therapeutic system in which a disease is treated by producing a second condition that is incompatible with or antagonistic to the first."  Dorland's Illustrated Medical Dictionary also defines it as a "term applied to that system of therapeutics in which diseases are treated by producing a condition incompatible with or antagonistic to the condition to be cured or alleviated. Called also heteropathy," e.g. treating a fever by immersion in cold water. This usage contrasts with the philosophy of homeopathy, which treats disease by prescribing agents that cause symptoms similar to the condition to be cured, e.g. treating a fever by wrapping in warm blankets.  Hence the terms homeopathy, meaning a treatment "similar to the suffering" and heteropathy, meaning a treatment "opposing of the suffering."

## Usage controversy, critiques of modern medicine
Tabor's Cyclopedic Medical Dictionary presents the application of the term allopathy to conventional medicine as incorrect, saying it is "erroneously used for the regular practice of medicine to differentiate it from homeopathy". WA Newman Dorland's American Pocket Medical Dictionary also labelled allopath and allopathist as "incorrect title for a regular practitioner" and described allopathy as an "erroneous name for the regular system of medicine." Many have criticized the use of the pejorative term to describe modern, conventional medicine.  Other terms that have been proposed to describe the conventional Western medical system of practice include: conventional medicine, Western medicine, evidence-based medicine, clinical medicine, scientific medicine, regular medicine, mainstream medicine, standard medicine, orthodox medicine, and authoritarian medicine.  Nevertheless, the usage of allopathic medicine persists, by both critics and practitioners of modern, Western medicine.

## Changing Definitions
HOBLYNS DICTIONARY OF MEDICAL TERMS, 1892
OXFORD ENGLISH DICTIONARY, 1971
DORLANDS ILLUSTRATED MEDICAL DICTIONARY, 1971
STEDMAN'S MEDICAL DICTIONARY, 2007
MERRIAM-WEBSTER'S ONLINE DICTIONARY, 2007

# Regional usage of term

## In the United States
In the United States, the term is used frequently in discussions of either the osteopathic medical profession or alternative medicine.  Some authors have raised concerns that it is misused, or question if it even has a meaning. Norman Gevitz, a medical historian, explains the term as follows.
Although policy makers, social scientists, and others often refer to the MD profession as allopathic, this term is actually an historical artifact that does not reflect any body of beliefs shared by the members of this profession.  For more than 150 years, the American Medical Association has pointedly rejected the adoption of any philosophical belief system governing health and disease and has argued that the profession's approach to medicine is based solely on scientific   evidence.

## In India
In India, the term allopathic is frequently used to distinguish modern, Western, research-based medicine from the many traditional forms of medicine practiced on the Indian subcontinent, especially ayurvedic medicine.

# Variants
- An allopathic physician is one who holds a certain medical degree: the Doctor of Medicine (MD) or the Bachelor of Medicine and Surgery (MBBS, MBChB, MBBChir, etc).
- Allopathic medicine or allopathy, a term for scientific, research-based orthodox medicine.
- Allopath or allopathist, one who practices allopathy.