There are a number of hypothesis that explain why acupuncture consistently works and also lessens pain, although no one definitive answer has been adopted by the medical community. Among frequently cited explanations are:
"Augmentation of Immunity" - this is a theory points to the fact that Acupuncture has been clinically shown to raise white blood counts, overall anti-body levels and levels of specific hormones which act together to boost the immune system.
In Chinese medicine, there is the saying, "Where there is pain, there is stagnation. Whether that stagnation is caused by blood (as in a bruise), chi , cold, heat, or moisture (such as edema in the extremities), or any combination thereof, by inducing movement in the body Acupuncture works to reduce the pain that accompanies stagnation.
“Circulatory theory” states that acupuncture has the effect of constricting or dilating blood vessels thus improving circulation. This may be caused by the body's release of vasodilators (such as Histamine), in response to acupuncture.