What a silly question! At least this is what most sceptics would say: if we are not sure that it works, we do not need to spend any thoughts on a potential mechanism!

However, in the realm of acupuncture, the potential mode of action remains a hotly debated and fundamentally relevant issue.

The TCM folks, of course, ‘knew’ all along how acupuncture works: it re-balances the life-forces yin and yang. This is a nice theory – it has but one disadvantage: it has no bearing whatsoever on reality. Vitalistic ideas such as this one have long been proven to be nothing but fantasy.

Meanwhile, several more plausible hypotheses have been developed, and hundreds of papers have been published on the subject. One recent article, for instance, suggests a range of mechanisms including microinjury, increased local blood flow, facilitated healing, and analgesia. Acupuncture may trigger a somatic autonomic reflex, thereby affecting the gastric and cardiovascular functions. Acupuncture may also change the levels of neurotransmitters such as serotonin and dopamine, thereby affecting the emotional state and craving… By affecting other pain-modulating neurotransmitters such as met-enkephalin and substance P along the nociceptive pathway, acupuncture may relieve headache. Acupuncture may affect the hypothalamus pituitary axis and reduce the release of the luteinizing hormone…

Another article states that the Western explanation for acupuncture effectiveness is based upon more than half a century of basic and clinical research, which identified the activation of sensory system and the subsequent activity-dependent regulation of neurotransmitters, neurohormones, and several classes of neuromodulators as plausible mechanism for the acupuncture‘s therapeutic properties. The regulation of neurotrophins’ expression and activity is one of the possible neurophysiological mechanisms underlying acupuncture‘s effects on neuropathic pain, nerve injury, neurodegeneration, and even in the regulation of gonadal functions…

Recently Burnstock proposed that mechanical deformation of the skin by needles and application of heat or electrical current leads to release of large amounts of ATP from keratinocytes, fibroblasts and other cells in skin; the ATP then occupies specific receptor subtypes expressed on sensory nerve endings in the skin and tongue; the sensory nerves send impulses through ganglia to the spinal cord, the brain stem, hypothalamus and higher centres; the brain stem and hypothalamus contain neurons that control autonomic functions, including cardiovascular, gastrointestinal, respiratory, urinogenital and musculo-skeletal activity. Impulses generated in sensory fibres in the skin connect with interneurons to modulate (either inhibition or facilitation) the activities of the motoneurons in the brain stem and hypothalamus to change autonomic functions; specifically activated sensory nerves, via interneurons, also inhibit the neural pathways to the pain centres in the cortex.

A brand-new article in the journal SCIENTIFIC AMERICAN puts the hypothesis in perspective:

…scientists have been studying a roster of potential biological pathways by which needling might relieve pain. The most successful of these efforts has centered on adenosine, a chemical believed to ease pain by reducing inflammation. A 2010 mouse study found that acupuncture needles triggered a release of adenosine from the surrounding cells into the extracellular fluid that diminished the amount of pain the rodents experienced. The mice had been injected with a chemical that made them especially sensitive to heat and touch. The researchers reported a 24-fold increase in adenosine concentration in the blood of the animals after acupuncture, which corresponded to a two-thirds reduction in discomfort, as revealed by how quickly they recoiled from heat and touch. Injecting the mice with compounds similar to adenosine had the same effect as acupuncture needling. And injecting compounds that slowed the removal of adenosine from the body boosted the effects of acupuncture by making more adenosine available to the surrounding tissue for longer periods. Two years later a different group of researchers went on to show that an injection of PAP, an enzyme that breaks other compounds in the body down into adenosine, could relieve pain for an extended chunk of time by increasing the amount of adenosine in the surrounding tissue. They dubbed that experimental procedure “PAPupuncture.”

Both sets of findings have excited researchers—and for good reason. The current options for treating pain are limited and rely mostly on manipulating the body’s natural pain-management system, known as the opioid system. Opioid-based painkillers are problematic for several reasons. Not only does their efficacy tend to wane over time, but they have been linked to an epidemic of addiction and overdose deaths across the U.S.—so much so that the Centers for Disease Control and Prevention has recently advised doctors to seriously restrict their use. The available nonopioid pain treatments are few; many of them require multiple injections or catheterization to work; and they often come with side effects, such as impaired movement. Adenosine offers an entirely new mechanism to exploit for potential treatments—one that may come with fewer side effects and less potential for addiction. What is more, adenosine can be made to circulate in the body for prolonged stretches. Pharmaceutical companies are actively investigating adenosine-related compounds as potential drugs.

But however promising adenosine may be as a treatment, the findings from this research do not prove that acupuncture itself “works.” For one thing, the researchers did not show that the release of adenosine was specific to acupuncture. Acupuncture needles might cause adenosine to flood the surrounding tissue, but so might a hard pinch, or applied pressure, or any number of other physical insults. In fact, both of the studies found that when adenosine was turned on in mouse tissue by other mechanisms, the pain response was equal to or better than the response generated by acupuncture. For another thing, the study results offered no support for the use of acupuncture to treat any of the other conditions for which the procedure is often advertised. A localized adenosine response may mitigate localized pain. That does not mean it can also cure insomnia or infertility.

It may well be that the reams of research scientists have done on acupuncture have lit the path toward improved understanding of—and eventually better treatments for—intractable pain. But it may also be time to take whatever bread crumbs have been laid out by that work and move on.


As we see, there is no shortage of potential explanations as to HOW acupuncture works. The most plausible theory still is that it works largely or even exclusively via a placebo effect.

Due to this type of mechanistic research, acupuncture has gained much credibility. The question is, does it deserve it? In my view, it would be much more fruitful to first make sure THAT acupuncture works (beyond a placebo response) and, if so, for what conditions. The question HOW it works is unquestionably interesting but in the final analysis it probably is secondary.

20 Responses to How does acupuncture work?

    • This article on the same subject in Scientific American is so fresh it’s dated 12 days ahead from today 🙂

      I highly recommend the blog (“SBM” for short) where Dr. Gorski and many more extremely competent writers are active. If you want to delve deeper into the where, when, how and why’s of acupuncture you could do worse than look that keyword up on SBM (The list of SBM posts about acupuncture on this page seems to reach only up to 2013 so for more recent articles put “acupuncture” in the search box).

      I specially recommend the series “Acupuncture Anesthesia”: A Proclamation from Chairman Mao by Kimball Atwood that starts here and also the articles on its history by Ben Kavoussi (See his posts in the list under the link above).

      • How many times have I recommended Bausell’s “Snake Oil Science” when the subject of acupuncture arises? I need a check from his publisher.

        I can’t say I’ve ever read a better layman-accessible book for gaining an understanding the placebo effect and acupuncture.

  • “Vitalistic ideas such as this one (yin-yang theory) have long been proven to be nothing but fantasy.”

    That’s interesting, do you have references for that? How was yin-yang theory proven to be fantasy?

  • How has “yin-yang” theory been proven to be FACT?

    • Yin yang theory is a way of comparing things. I’m curious how somebody proved that things cannot be compared. Whoever told Edzard that it was proven to be fantasy was pulling his leg.

      • Hi JM , cane you prove different if some I would be interested.

      • You are begging the question. I can compare flying pigs and giant, world-eating chickens.

        It does not follow that these things exist.

        • I’m begging the question: which would make a better t-shirt for Edzard’s online store?

          “Vitalistic ideas such as yin-yang theory have long been proven to be nothing but fantasy.”


          “Each branch of alternative practitioners seem to have created their very own diagnoses”

          Maybe there could be a world-eating chicken on the back of the shirt…

          • “Yinyang (yin-yang) is one of the dominant concepts shared by different schools throughout the history of Chinese philosophy…” — Internet Encyclopedia of Philosophy.

            The commentators “jm”, “len”, and others continually scold those of us who do not understanding, and those of us who misunderstand, this ‘theory’.

            Firstly, it isn’t a theory at all; it is simply ancient conjecture, it is not even a testable hypothesis.

            Secondly, some commentators try very hard to distract us from the real issue, which is not *what* the ‘theory’ is about, it is all about *why* is it still being deployed in the 21st Century?

            Those who invoke this ‘theory’ know full well that it provides them with zero explanatory power and explanatory depth in the modern world. Their only recourse is to continue to pretend that they have wisdom and insight far beyond all those who have not yet properly understood ancient wisdom. They have chosen to reject the hard path of seeking the truth in the modern world. They have chosen instead to tread the easy path of pretending to know things that they don’t know, which is a well established method of exploiting vulnerable members of society. Lucrative, yes! Ethical, no!

            Yinyang (yin-yang) ‘theory’ was developed for the sole purpose of explaining — with an air of authority — the inexplicable to the uninformed. It’s alt-med jargon for: I don’t know what the eff I’m talking about, but I’m gonna make damn sure that my clients don’t cotton on to the fact that I’m bullshitting them.

          • Pete

            “Those who invoke this ‘theory’ know full well that it provides them with zero explanatory power and explanatory depth in the modern world.”

            That’s not true at all. I compare things all the time, and this is a useful model. And it’s not a model for explanatory depth. It’s broad and general and quite relative.

            “ Their only recourse is to continue to pretend that they have wisdom and insight far beyond all those who have not yet properly understood ancient wisdom.”

            Also not true. The concept is as simple as simple can be – I’m not sure it qualifies as “ancient wisdom”. And no wisdom or insight is needed to understand that if you have a sunny side of a hill…you also have a shady side. And they are in the process of changing.

            “They have chosen to reject the hard path of seeking the truth in the modern world.”

            Given the topic…that’s quite funny. I hope you can see the humor.

          • Jm wrote: “I compare things all the time, and this is a useful model.”

            Here’s a reminder of the last time you invoked yin-yang to compare things:

            Don’t forget to read the replies to these asinine statements that you made:
            Here’s how yin yang theory would be used in relation to the following:
            A gas turbine engine – off, yin. On, yang. Same with a television system. The internet, yang, an intranet, yin. The Hubble Space Telescope, yang. My binoculars, yin. The human body…yin compared to a mountain. Yang compared to a mole hill.

          • Pete

            The quote was answering your question in the comment directly above. You asked how yin/yang applied to those specific things (“…a gas turbine engine; a television system; the Internet; the Hubble Space Telescope; the human body), and how to repair them. You actually think I was the asinine one in that exchange?

            Edzard said “Vitalistic ideas such as this one (yin-yang theory) have long been proven to be nothing but fantasy.” Yin yang theory isn’t a vitalistic idea. I’m not sure where he got that from.

  • A good article but complicated, a simple statement is that there are energy lines within the mental/emotional body and yes we do have 3 bodies, These energy lines connect to every organ within the body and when a blockage occurs within a meridian then that blockage has to be identified and cleared, you then ask if the blockage is within a meridian and the meridian is in the mental/emotional body who can it be found so it can be cleared, not an easy question to answer as to many people do not believe that there is a bio-field in and around the physical but it does exist.
    When a female has a caesarean operation performed to facilitate a Birth up to 5 meridians are cut but the surgeon will deny that they do not exist as they cannot be seen but it happened. The woman does not recognise that problems exist because throughout the pregnancy hormones have been injected into the body from the peturity gland to allow for her to carry and allow the fetus to develop, so after the birth she does not recognise any problems. For the last 5 years I have worked with numerous women who have had that problem and rectified the problem

  • Well done Len.
    We await publication of your work and outcomes with interest.
    As a start, perhaps you could identify yourself, or I will be in danger of indulging in fantasy.
    Thank you.

  • Pretty sure I read an article in a magazine similar to Scientific American about how it *could* be mechanical stimulation, like there might be some kind of connective tissue network that transmit the forces. (Don’t remember which magazine. Sorry!) I might hypothesize that maybe if hypothesis-driven research hasn’t found the mechanism, perhaps more exploratory research or case reports could give a better hypothesis to test? In Chinese medicine, two people with the exact same condition could be treated very differently, so when it comes to RCTs aggregating all the data together, that might be a reason why it hasn’t shown an effect. In addition, many of these studies are poorly designed.

    With skepticism, I decided to try this myself after my PhD research supervisor (a prominent scientist and a full-on anti-alternative medicine person) tried acupuncture for once just so he could get off narcotics for pretty severe pain. He said he was very skeptical and because he didn’t believe it, it couldn’t have been placebo effect, yet he found that it worked immediately for him. So far, I’ve seen great results from acupuncture treatments, and I observe some physiological improvements like HRV pre- and post- treatment measurements, general pain levels, and anxiety. I don’t know if someone could will their HRV number to improve through placebo effects. Just a personal anecdote.

    • “Just a personal anecdote.” And if you read further on this blog you’ll easily run into somebody saying, as I’m now going to: the plural of anecdote is anecdotes, not data.

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