Several theories have been presented as to exactly how acupuncture works. One theory suggests that pain impulses are blocked from reaching the spinal cord or brain at various “gates” to these areas. Since a majority of acupuncture points are either connected to (or are located near) neural structures, this suggests that acupuncture stimulates the nervous system.
Another theory suggests that acupuncture stimulates the body to produce narcotic-like substances called endorphins, which reduce pain. Other studies have found that other pain-relieving substances called opiods may be released into the body during acupuncture treatment.