Like energy medicine, homeopathy may be one of the most difficult areas for the Western allopathic physician to comprehend. Homeopathy includes several tenants and theories that are antithetical to Western thought. Homeopathy is derived from the Greek words homoios, which means similar, and pathos, which means suffering. The German physician Samuel Hanneman, for whom the US medical school is named, developed homeopathy.

In the United States homeopathic medicines are recognized and regulated by the Food and Drug Administration due to their long history of use in this country. In fact, the first United States Pharmacopoeia of Homeopathic Medicine was published in 1897. Like many things in science, Dr. Hanneman discovered homeopathy by serendipity. He was studying the bark of the cinchona tree known for its ability to treat malaria. Dr. Hanneman did not have malaria at the time that he was experimenting with this bark. He ingested some and noted that it caused symptoms very similar to malaria. He theorized that a curative substance, when given to a healthy person, might cause symptoms of the disease being treated. He then experimented over the next several years with hundreds of other compounds and found similar findings. He formulated the three major laws of homeopathy which are:

1. Like cures like, known as the law of similars
2. The greater the dilution the greater its potency, known as the law of infinitesimal dose
3. An illness is specific to the individual.

Looking more closely at "like cures like", Dr. Hanneman said, "Each individual case of a disease is most surely, radically, rapidly, and permanently annihilated and removed only by a medicine capable of producing (in the human system) the most similar and complete manner of totality of the symptoms." It is interesting to note that Hypocrites articulated this "law of similars" in the 4th century BC after his long study of the treatment of disease with herbs. It was also the basic theory used by Edward Jenner, Jonas Salk and Louis Pasteur during the development of the theories of immunization.

One example of "like cures like" is the treatment of allergies. In an individual allergic to cat dander, small amounts of cat dander are injected into the patient which over time causes resolution of symptoms. The most controversial aspect of homeopathy is the second law, the "law of infinitesimal dose". It is felt in homeopathic circles that the more dilute a remedy, the greater its potency. In some cases, homeopathic remedies are diluted to such a point that it is unlikely that any active ingredient remains in the remedy. This of course has been the main criticism of homeopathy. Recently, however, research by the German biophysicist, Dr. Wolfgang Ludwig, has shown that the hydrogen bonding angles of the solvents used in preparation of homeopathic substances is different than native water. He theorizes that homeopathic substances may carry some electromagnetic signal or other information carrying capacity.

The third law in homeopathy is that "an illness is specific to the individual". In other words, a cold is not a cold. Each cold is unique to the individual who has the cold. It is those unique symptoms that should be exploited through the "law of similars" in order to most completely eradicate that cold. The Homeopathic Materia Medica, is a book that lists not only remedies, but also exhaustive lists of symptoms associated with those remedies. The goal of homeopathy is to carefully match a person's global symptoms complex with a specific medicine. The closer the match, the greater the likelihood of a successful outcome. Dilutions are chosen by the degree of match. The poorer the match of symptoms, the lower the dilution. In other words, the more medication is given. The more precise the match, the higher the dilution, the less substance is actually given.

Another important aspect of homeopathy is what has come to be known as Herring's law. Dr. Constantine Herring is felt to be the father of American homeopathy. It was his observation that the healing process progresses from the deepest part of the body to the extremities, from the emotional and mental aspects to the physical, and from the upper part of the body to the lower part of the body. Healing also progresses in a reverse chronological order, from the most recent maladies to the oldest. By understanding Herring's law, homeopaths are able to determine if their patients are indeed improving or if they are developing new illness patterns.