Current scientific research indicates that traditional forms of acupuncture are more effective than placebos in the relief of certain types of pain and post-operative nausea. Other reviews have concluded that positive results reported for acupuncture are too small to be of clinical relevance and may be the result of inadequate experimental blinding, or can be explained by placebo effects and publication bias.

Acupuncture's use for certain conditions has been endorsed by the United States National Institutes of Health, the National Health Service of the United Kingdom, the World Health Organization, and the National Center for Complementary and Alternative Medicine. Some scientists have criticized these endorsements as being unduly credulous and not including objections to or criticisms of the research used to support acupuncture's effectiveness.

There is general agreement that acupuncture is safe when administered by well-trained practitioners using sterile needles and carries a very low risk of serious adverse effects.

The general theory of acupuncture is based on the premise that bodily functions are regulated by an energy called qi which flows through the body; disruptions of this flow are believed to be responsible for disease. Acupuncture describes a family of procedures aiming to correct imbalances in the flow of qi by stimulation of anatomical locations on or under the skin (usually called acupuncture points or acupoints), by a variety of techniques. The most common mechanism of stimulation of acupuncture points employs penetration of the skin by thin metal needles, which are manipulated manually or by electrical stimulation.