Alternative (Natural) medicine is any practice that is put forward as having the healing effects of medicine,but does not originate from evidence gathered using the scientific method.

Alternative medical systems can be based on common belief systems that are not consistent with facts of science, such as in naturopathy or homeopathy.

Alternative medical systems may be based on traditional medicine practices, such as traditional Chinese medicine, Ayurveda in India, or practices of other cultures around the World.

"Alternative medicine" is a loosely defined set of products, practices, and theories that are believed or perceived by their users to have the healing effects of medicine.

A United States government agency, the National Center on Complementary and Integrative Health (NCCIH), has created its own classification system for branches of complementary and alternative medicine.

"CAM", meaning "complementary and alternative medicine", is not as well researched as conventional medicine which undergoes intense research before being released to the public.

A research methods expert and author of "Snake Oil Science", R. Barker Bausell, has stated that "it's become politically correct to investigate nonsense.

Complementary and alternative medicine (CAM) has been described as a broad domain of healing resources that encompasses all health systems.

Alternative therapies lack the requisite scientific validation, and their effectiveness is either unproved or disproved. 

Some commentators have said that special consideration must be given to the issue of conflicts of interest in alternative medicine. 

Many of the claims regarding the safety and efficacy of alternative medicine are controversial. Some alternative treatments have been associated with unexpected side effects, which can be fatal.

Funding for research into effectiveness of alternative treatments comes from a variety of public and private sources.

Physicians who practice complementary medicine usually discuss and advise patients as to available complementary therapies.