Alternative medicine is any practice that aims to achieve the healing effects of medicine despite lacking biological plausibility, testability, repeatability, or evidence from clinical trials. Complementary medicine (CM), complementary and alternative medicine (CAM), integrated medicine or integrative medicine (IM), and holistic medicine attempt to combine alternative practices with those of mainstream medicine. Alternative therapies share in common that they reside outside of medical science and instead rely on pseudoscience. Traditional practices become "alternative" when used outside their original settings and without proper scientific explanation and evidence. Frequently used derogatory terms for relevant practices are new age or pseudo- medicine, with little distinction from quackery. Some alternative practices are based on theories that contradict the established science of how the human body works; others resort to the supernatural or superstitious to explain their effect or lack thereof. In others, the practice has plausibility but lacks a positive risk–benefit outcome probability. Alternative medicine is distinct from scientific medicine, which employs the scientific method to test plausible therapies by way of responsible and ethical clinical trials, producing repeatable evidence of either effect or of no effect. Research into alternative therapies often fails to follow proper research protocols (such as placebo-controlled trials, blind experiments and calculation of prior probability), providing invalid results. Much of the perceived effect of an alternative practice arises from a belief that it will be effective (the placebo effect), or from the treated condition resolving on its own (the natural course of disease). This is further exacerbated by the tendency to turn to alternative therapies upon the failure of medicine, at which point the condition will be at its worst and most likely to spontaneously improve. In the absence of this bias, especially for diseases that are not expected to get better by themselves such as cancer or HIV infection, multiple studies have shown significantly worse outcomes if patients turn to alternative therapies. While this may be because these patients avoid effective treatment, some alternative therapies are actively harmful (e.g. cyanide poisoning from amygdalin, or the intentional ingestion of hydrogen peroxide) or actively interfere with effective treatments. The alternative medicine sector is a highly profitable industry with a strong lobby, and faces far less regulation over the use and marketing of unproven treatments. Its marketing often advertises the treatments as being "natural" or "holistic", in comparison to those offered by medical science. Billions of dollars have been spent studying alternative