According to the University of Arizona's Center for Integrative Medicine:
Integrative Medicine (IM) is healing-oriented medicine that takes account of the whole person, including all aspects of lifestyle. It emphasizes the therapeutic relationship between practitioner and patient, is informed by evidence and makes use of all appropriate therapies.
The Defining Principles of Integrative Medicine
Integrative Medicine Resources
Naturopathic Medicine: What it is, frequently asked questions and how to find a licensed naturopathic doctor
Holistic Primary Care's Quality Counts: A Clinician’s Guide to Supplement Quality (pdf), published in the fall of 2017 by one of the leading integrative medicine journals, is a 24-page resource for clinicians and consumers, covering supplement regulations and enforcement, quality initiatives, delivery systems, probiotics, omega-3s and much more!
Whenever I write about mental health and integrative therapies, I am accused of being prejudiced against pharmaceuticals. So let me be clear - integrative medicine is the judicious application of both conventional and evidence-based natural therapies.
— Andrew Weil, M.D.