The delineation of what is medicine and what is not is a source of debate.

The major innovations introduced by Western medicine from the nineteenth century (anesthesia and antisepsis and vaccination and antibiotics in the nineteenth century), its successes and its dissemination throughout the world particularly through the colonization by the West will encourage them to ask in the first half of the twentieth century, Western scientific medicine as a unique model of medicine worldwide. The establishment of an international conventional medicine explains the use of the term still used "unconventional medicine" to refer to other medicines.

This implies the rejection by institutions outside the medical definition of old western medicines, including medicine dealt with medieval obscurantist, and non-Western traditional medicine, including the most structured of all the Chinese medicine.

However, in the late twentieth century, certain limitations faced by medicine (resistance to antibiotics as a result of misuse, adverse chemicals, failure to meet certain viruses, etc..) led to reconsider the alternatives of medicine.

This shift has resulted in the development in the West, scaled the face of modern scientific medicine, medicine alternatives, "soft", traditional or foreign, such as the homeopathy, the herbal medicine, the acupuncture, etc..

Also, always at the end of the twentieth century, including the effects of globalization, traditional medicines or non-Western, have seen their recognized place in the world medicine: in 2002, the World Health has set up its first global strategy on traditional medicine.

Some researchers even rehabilitate some of the aspects of medicine medieval West. As the medical historian Roger Dachez highlighting the preventative and holistic view of medicine had the Middle Ages Android app