Alternative medicine is defined as "any of various systems of healing or treating disease (as chiropractic, homeopathy, or faith healing) not included in the traditional medical curricula taught in the United States and Britain". Complementary medicine is defined as "any of the practices (as acupuncture) of alternative medicine accepted and utilized by mainstream medical practitioners". The term complementary and alternative medicine (CAM) is an umbrella term for both branches. CAM includes practices that incorporate spiritual, metaphysical, or religious underpinnings; non-evidence based practices, non-European medical traditions, or newly developed approaches to healing.
The list of therapies included under CAM changes gradually. If and when an approach regarded as "unproven therapy" is proven to be safe and effective, it may be adopted into conventional health care and over time may cease to be considered "alternative".