Although the medical doctrine of Homeopathy dates back to Hippocrates (462-377 B.C.), its basic principles, still recognized, are due to the German physician Hahnemann (1755-1843). In Homeopathy, pathological states are treated with remedies that in a healthy person would produce symptoms similar to those found in the pathological state. This is the main difference between Homeopathy and Conventional Medicine. The latter tends to follow the Law of Opposites by administering drugs that counteract the action triggered by the body, such as antipyretics for fever. Homeopathy instead follows the Law of Similars, for which the homeopathic remedy promotes the action triggered by the body while respecting and facilitating the mechanisms of physiological reaction. Instead of fighting directly the pathological state, homeopathic remedies stimulate the body to combat it. This action is compared to vaccination, in use in Conventional Medicine, fairly superficial, because homeopathic remedies are highly diluted and especially individualized on the person in relation to his specific symptoms and particular pathophysiological characteristics. Homeopathy is practiced in Europe, Asia and North America since the second half of the nineteenth century. This therapeutic method has been integrated into the National Health System in many States such as India, Mexico, Pakistan, Sri Lanka and United Kingdom.