The following is from a study by the World Health Organization:

The situation in the use of traditional and complementary/alternative medicine:
Traditional and complementary/alternative medicine is widely used in the prevention,
diagnosis, and treatment of an extensive range of ailments. There are numerous
factors that have led to the widespread and increasing appeal of traditional and
complementary/alternative medicine throughout the world, particularly in the past 20
years. In some regions, traditional and complementary/alternative medicine is more
accessible. In fact, one-third of the world’s population and over half of the populations
of the poorest parts of Asia and Africa do not have regular access to essential drugs.
However, the most commonly reported reasons for using traditional and
complementary/alternative medicine are that it is more affordable, more closely
corresponds to the patient’s ideology, and is less paternalistic than allopathic
medicine. Regardless of why an individual uses it, traditional and complementary/alternative
medicine provides an important health care service to persons both
with and without geographic or financial access to allopathic medicine.

Traditional and complementary/alternative medicine has demonstrated efficacy in
areas such as mental health, disease prevention, treatment of non-communicable
diseases, and improvement of the quality of life for persons living with chronic
diseases as well as for the ageing population. Although further research, clinical trials,
and evaluations are needed, traditional and complementary/alternative medicine has
shown great potential to meet a broad spectrum of health care needs.

legal Status of Traditional Medicine and Complementary / Alternative Medicine: A Worldwide Review (2001)  page 3