How Does Acupuncture Work?

The exact mechanisms by which acupuncture might produce effects on the body remain unknown. Weak preliminary evidence from the 1970s hints that acupuncture encourages the release of endorphins (morphine-like compounds that function as the body's internal pain-regulating substances). 2 Support for this theory comes from a study in which use of the drug naloxone, which opposes the effects of endorphins, was found to block pain relief from acupuncture. 3 However, the body releases endorphins in response to any sort of pain, and it may be that it is needle-insertion per se, and not acupuncture, that is responsible for the rise in endorphins. Furthermore, there is some evidence that the placebo effect itself works by means of endorphins—in one study, naloxone blocked the ability of a placebo treatment to reduce pain. 4 It has also been proposed that acupuncture may influence other chemicals in the body that control various physiologic activities. Preliminary studies have shown possible effects of acupuncture on norepinephrine, acetylcholine, and cyclic AMP, all of which are "chemical messengers" that regulate key systems in the body. 5 However, none of this evidence is strong.