Artsy acupuncture needle design on mom's back

Alternative medicine is any healing practice "that does not fall within the realm of conventional medicine." It is based on historical or cultural traditions, rather than on scientific evidence.

A 1998 systematic review of studies assessing its prevalence in 13 countries concluded that about 31% of cancer patients use some form of complementary and alternative medicine. Alternative medicine varies from country to country. Jurisdictions where alternative medical practices are sufficiently widespread may license and regulate them. Edzard Ernst has said that in Austria and Germany complementary and alternative medicine is mainly in the hands of physicians, while some estimates suggest that at least half of American alternative practitioners are physicians. In Germany herbs are tightly regulated: half are prescribed by doctors and covered by health insurance based on their Commission E legislation.

Alternative medicine is frequently grouped with complementary medicine or integrative medicine, which, in general, refers to the same interventions when used in conjunction with mainstream techniques, under the umbrella term complementary and alternative medicine, or CAM. Some researchers in alternative medicine object to this categorization, preferring to emphasize differences of approach, but nevertheless use the term CAM, which has become standard. Critics maintain that the terms “complementary” and “alternative medicine” are deceptive euphemisms meant to give an impression of medical authority.

Alternative medicine methods are diverse in their foundations and methodologies. Methods may incorporate or base themselves on traditional medicine, folk knowledge, spiritual beliefs, or newly conceived approaches to healing. "Although heterogeneous, the major CAM systems have many common characteristics, including a focus on individualizing treatments, treating the whole person, promoting self-care and self-healing, and recognizing the spiritual nature of each individual. In addition, many CAM systems have characteristics commonly found in mainstream healthcare, such as a focus on good nutrition and preventive practices. Unlike mainstream medicine, CAM often lacks or has only limited experimental and clinical study; however, scientific investigation of CAM is beginning to address this knowledge gap. Thus, boundaries between CAM and mainstream medicine, as well as among different CAM systems, are often blurred and are constantly changing."