Acupuncture: does it work and, if so, how?

This article is intended to assist physicians in giving advice to their patients about acupuncture. Despite 20 years of research, the efficacy of acupuncture in general is not established. One of the difficulties with drawing conclusions from the existing literature is that the term acupuncture is used to describe a variety of treatments that differ in many important aspects, both theoretical and technical. This article critically reviews the existing evidence supporting the various effects that have been proposed to result from acupuncture treatments. The evidence is classified according to level of effect (eg, local, segmental, generalized) and type of acupuncture treatment (eg, manual v electrical acupuncture).