What’s the science behind acupuncture?

Recent studies offer insights into how the ancient technique works, while newer approaches are bolstering acupuncture with insights from Western medicine.

For more than 35 years in Liaoning Province, China, Min Chen worked to restore her patients’ physical, mental, and emotional health by, as she puts it, “regulating the flow of qi and blood, balancing yin and yang, and harmonizing organ functions through the meridians.” Her treatment of choice was acupuncture, a millennia-old practice and a core component of Traditional Chinese Medicine (TCM).

Recent discoveries have helped acupuncture gain scientific footing, bolstering Western acceptance of the technique and strengthening the case that acupuncture’s benefits are more than just a placebo effect. Image credit: Shutterstock/Andrey_Popov.

Chen moved to the United States two years ago and now brings the same philosophy and techniques to patients in Seattle. But she has noticed differences in how Americans approach her work. “I meet clients who are curious or even a little skeptical about acupuncture, especially if they are trying it for the first time,” she says. “Many people here want to understand the scientific basis, safety, and mechanism before receiving treatment.”

Chen welcomes the probing questions—“How does acupuncture work?” and “Why do the needles help with pain or stress?”—because increasingly, she can offer evidence-based answers. Since Chen first trained in acupuncture, the scientific literature has dramatically expanded, from clinical trials demonstrating benefits for a growing range of conditions to laboratory studies uncovering multiple biological pathways for both the local and holistic effects of acupuncture.

Although the picture remains incomplete, several lines of research are elucidating the biological underpinnings of acupuncture. They include the involvement of endogenous opioids and the role of loose connective tissue—including fascia, a body-wide network of collagen fibers embedded in an extracellular matrix rich in hyaluronic acid and other proteins. This tissue could be the medium that transmits the effects of local needling to distant systems, echoing the TCM concept of meridians.

By giving ancient ideas a modern scientific footing, recent discoveries are bolstering Western acceptance and strengthening the case that acupuncture’s benefits are not just a placebo effect. “Clinical evidence is important,” says Peter Wayne, director of research for the Osher Center for Integrative Health at Harvard Medical School and Brigham and Women’s Hospital, in Boston. “But without plausible mechanisms, community uptake is much slower.”

Western science and technology are also creating opportunities to enhance acupuncture practice with knowledge from the burgeoning field of bioelectronic medicine (1). Still, many researchers and practitioners marvel at the sophistication of the original practice. “How on earth did they understand that a point lateral in the fifth digit of the foot connected to the eye system?” asks Jeremy Pulsifer, an acupuncturist in New York City. “Modern science is finally saying, ‘We don’t know how they knew, but somehow there was an awareness that is far more sophisticated than we’ve ever given them credit for.’”

A Pain-full Start

In 1971, James Reston, a reporter with The New York Times, underwent an emergency appendectomy in China while covering President Richard Nixon’s historic visit. To treat his postsurgical pain, a doctor inserted three long, thin needles into his right elbow and below his knees. “There was a noticeable relaxation of the pressure and distension within an hour and no recurrence of the problem thereafter,” he later reported (2).

Reston’s account sparked American interest in acupuncture. Curiosity grew into momentum in the 1990s and early 2000s as opioid prescriptions—and overdoses—soared. “We got hit so hard with opioid deaths, funding came in to research safer options,” says Arya Nielsen, an acupuncturist and fellowship director at Icahn School of Medicine at Mount Sinai in New York.

But early acupuncture research focused primarily on clinical tests and produced mixed results. Most puzzling, about half of trials suggested that it didn’t matter where needles were placed; comparable improvements were seen among participants receiving various forms of “sham” acupuncture, too (3, 4). A nagging question slowed trust in the practice: Could the benefits be simply attributed to a placebo effect?

Researchers pushed on with studies using stricter blinding and more sophisticated sham controls, including retractable needles that touch but don’t pierce the skin. By the early 2010s, enough clinical data accumulated to demonstrate that active acupuncture was still more effective than sham or standard care—helping people with chronic low-back pain, osteoarthritis, postsurgical pain, and the painful side effects of cancer treatment (5). By allowing cancer patients to stay on medication, acupuncture even appeared to help them live longer, says Helene M. Langevin, former director of the National Center for Complementary and Integrative Health in Bethesda, Maryland.

What’s more, the effects persisted. At one year, those who had received acupuncture lost only an average of 15% of the benefit in a key 2018 meta-analysis of data on more than 20,000 patients (6). “I don’t know that anyone has produced that result for NSAIDs,” Nielsen says, referring to nonsteroidal anti-inflammatory drugs. She coauthored a study published in September 2025 that found acupuncture eased lower back pain in older adults more effectively than standard care and with lasting benefits at 12 months (7). Still, these kinds of studies didn’t shed any further light on why acupuncture works.

The dispersed tattoo ink shows the continuity of the interstitium within and between organs—here, the colon—suggesting a body-wide communication network of fluid-filled spaces. Acupuncture’s meridian channels might correspond to this interstitium. Image credit: Reprinted from ref. 24, which is licensed under CC BY 4.0.

Tracing Multiple Pathways

A parallel line of research since the 1970s has sought to dispel doubts by deciphering the mechanisms behind acupuncture’s analgesic properties. Researchers have built a strong case that acupuncture targeting pain stimulates the release of the body’s own opioid-like chemicals, including endorphins, which bind to pain-regulating receptors (8). The theory solidified when studies found that naloxone, which blocks opioid receptors, hindered this effect (9).

Acupuncture works via nonopioid mechanisms, too, including adenosine released at the site of needling (10). Researchers also traced sensory signals from nerve endings near acupuncture needles as they traveled up the spinal cord to the brainstem. There, key brainstem centers appear to switch on descending pathways that release serotonin, norepinephrine, and opioids back into the spinal cord, blunting subsequent pain signals before they reach the brain (11, 12).

“It’s not only a local phenomenon,” says Moritz Hempen, a Munich-based physician trained in both Western medicine and TCM. “It now seems more important that the central nervous system is activated, creating a top-down effect.”

Evidence further suggests that acupuncture engages placebo-related networks in the brain that translate expectations into physiological changes (13). Even needling sham points can activate these circuits, sometimes with great benefit. Because sham acupuncture can also trigger genuine analgesic and other biological pathways, however, it is not a true placebo. Both factors may help explain some earlier confusing results, according to Nielsen. She authored another paper in September that argued a failure to account for the very real effects of sham controls led to widespread underestimation of acupuncture’s efficacy, noting that funders now prefer comparisons to standard care (4).

While some of the quick relief with acupuncture may come from endogenous opioids, adenosine, and expectations, longer-lasting benefits seem to involve other mechanisms, from immune system modulation to connective-tissue remodeling. Brain-imaging studies even suggest that regular acupuncture sessions may help the brain process pain differently over time by reshaping how the somatosensory cortex communicates with other regions that regulate pain, emotion, and stress (14).

Pain research has significantly outpaced studies of acupuncture’s other uses, but scientists are also making progress toward documenting broader clinical effects and their mechanisms. Hempen recently reviewed the literature and found strong support for benefits in conditions ranging from female infertility and menopausal symptoms to cancer-related fatigue and postoperative nausea and vomiting (15). Many more indications, including heart disease, are promising but understudied, he says.

As seen with pain, acupuncture most likely taps into multiple pathways to produce benefits. In asthma, there are clues that it may dial down inflammation in the immune system (16). In irritable bowel syndrome, it may improve communication between the gut and the brain (17). Some of the most intriguing new work is also beginning to reveal how needling a particular point on the body could trigger these distant responses.

Secret Superhighway

In TCM, acupuncture meridians are described as channels linking the body surface to internal organ systems. But this concept is less about using direct connections to treat a specific symptom, such as lower back pain, Chen says, and more about treating a person’s entire “pattern of imbalance.” As her training taught her, acupoints and meridians serve as both a “precise map for clinical practice and a holistic framework for treating the whole person—physically, mentally, and emotionally.” Each acupoint is “like a gateway that can influence local areas as well as the broader system,” she says.

Uniting all these portals may be highways of fascia and other connective tissues, which form a continuous network containing fluid-filled interstitial spaces, known as the interstitium. Those mysterious meridian channels, scientists say, may correspond to real pathways within the body.

A pioneer in this area, Langevin had her curiosity piqued when she noticed a tugging sensation in the skin as she withdrew acupuncture needles from patients. “There’s this interesting response that you can feel with your hands,” she says. That resistance, she discovered, came from collagen winding around the needle. It’s also the source of the dull aching feeling known in Chinese as “deqi” that patients often experience during treatment. Research by Langevin and others shows that when an acupuncture needle grasps onto collagen, the resulting stress ripples through the connective tissue, activating fibroblasts, releasing cytokines, and triggering immune responses that promote healing (18).

In two studies of tissue from mice, Langevin and her team found that this fibroblast activation peaked with two rotations of the acupuncture needle and extended several centimeters throughout the tissue (19). Fibroblast responses even differed by the direction in which the needles were rotated, whether back and forth or all in one direction (20). “We’re seeing very interesting stuff,” Langevin says. “The link from that to why people feel better still needs to be patched together.”

Hints are emerging that these local responses trigger signals that travel further afield through the interstitium. “This connective tissue is everywhere in the body—connecting every organ, every blood vessel, every nerve,” she says.

In another study, Langevin and colleagues mapped acupuncture points onto serial gross anatomical sections of the human arm and found an 80% overlap with connective tissue planes (21). And in separate research, Andrew Ahn, director of high-tech/soft-touch integration at the Osher Center in Boston, and his team injected a dye called fluorescein into the Pericardium 6 acupoint on the inner forearm and watched it slowly migrate deep into the tissue, through interstitial spaces, and then reappear at the Pericardium 3 acupoint on the inside of the elbow (22). Ahn says he was surprised, and amazed: “Whatever path this fluorescent dye migrated through closely corresponded with the described acupuncture point–meridian network.”

Ahn believes the dye traveled via interstitial fluid pathways within connective tissue. What propelled it—and specifically between the two acupoints—remains unknown; unlike blood vessels, the interstitium has no pumps or valves. He speculates that an electrical force may be at play.

The stiff fibrous network of collagen in the fascia might convert mechanical forces into electrical signals, says Neil Theise, a pathologist at the New York University Grossman School of Medicine, who coauthored papers in 2018 and 2021 detailing the anatomy of the interstitium for the first time (23, 24). The highly charged hyaluronic acid in the interstitial spaces might preferentially guide the movement of certain molecules and cells, he adds. “So, the fascia and its interstitium probably generate their own electrical currents independent of the nervous system,” Theise says, calling the prospect “tantalizing.”

Even as researchers explore how local needling could broadcast benefits over long distances via connective tissue and other pathways, more work is needed to understand what is going on at an acupuncture point that makes it a gateway.

EunMee Yang, an acupuncturist and postdoctoral research fellow at the Osher Center in Boston, is focused on that question. When treating a patient, she and other acupuncturists—Chen included—will gently palpate the skin to find tenderness, tension, or nodules in the tissues. Yang’s research indicates that needling these sensitive spots may be more effective than other skin areas in treating disease (25). And these spots, she says, “happen to correspond with acupoints.” Many traditional acupoints also fall in the seams between muscles, where connective tissue is especially dense, suggesting that they might provide efficient on-ramps to this communication highway. “A lot more needs to be done” to answer fundamental questions like, “’What is an acupuncture point?’ and ‘Can it be optimized?’,” she says.

A new project could help further connect those dots. The Topological Atlas and Repository for Acupoint research (TARA), funded by the NIH, aims to bridge TCM theory with modern anatomy and physiology through a searchable 3D human body atlas and database (26). To create the atlas portion of TARA, acupuncturists have labeled acupoints on volunteers with an adhesive marker that shows up bright on an MRI. The resulting images reveal the location of each point relative to underlying structures, including nerves and connective tissue.

TARA will incorporate existing databases of published clinical trials and basic science data. It will also link with other projects, such as the NIH’s Stimulating Peripheral Activity to Relieve Conditions (SPARC) program. This effort seeks to understand and harness the autonomic nervous system to treat disease, including through targeted electrical stimulation (27). “We think of this as almost creating a Rosetta Stone,” Langevin says. It is a merging of traditional millennia-old acupuncture knowledge, an expanding inventory of scientific data, and the expertise of acupuncturists, she says.

Once all the pieces of TARA are online within the next few years, artificial intelligence integrated with large-language models will allow users to click on any acupoint to see its 3D location, underlying anatomy, and related research on mechanisms and clinical outcomes. Or they could do the reverse—seek out acupoints most often used to lower blood pressure, for example.

“We still don’t know a lot about acupoints. The concept of meridians is more philosophical than physiological, and there are all kinds of theories about what they are.”

—Vitaly Napadow

“We still don’t know a lot about acupoints. The concept of meridians is more philosophical than physiological, and there are all kinds of theories about what they are,” says Vitaly Napadow, a radiologist and acupuncture researcher at Mass General Research Institute in Boston and a TARA principal investigator. “We’re trying to provide a product so people can go and test these concepts.”

Acupuncture needle rotations cause a connective tissue “whorl,” shown here in rat subcutaneous connective tissue. Numbers 0–7 indicate the number of acupuncture needle revolutions, indicating a growing whorl as the rotations increase. Image credit: Reprinted from ref. 21.

Adding a Spark

For one recent patient with constipation and joint inflammation, Chen placed a needle at the Stomach 36 acupoint below the kneecap and another at Spleen 9 below the inner knee. She then attached electrodes and set the current to between 2 and 4 hertz for 20 minutes. “It is gentle but effective in promoting energy flow and balancing organ function,” she says. Chen says she turns to electroacupuncture when stronger or more consistent stimulation is needed, such as with digestive dysfunction and chronic pain. A few studies suggest that electroacupuncture can be more effective than manual acupuncture, especially for certain types of pain. Different points, depths, frequencies, intensities, durations, and stimulation patterns can all produce different effects (28). For example, the analgesic effect of low-frequency 2-hertz electroacupuncture builds gradually, Pulsifer says. In Chinese hospitals, patients may receive 30 minutes of such stimulation before anesthesia, after which the pain relief can last for hours.

High-frequency electroacupuncture works in another way. “It’s immediate and unbelievably potent,” Pulsifer says. “The drawback: it’s temporary.” An ideal recipe for both immediate and lasting pain relief, he says, may be to alternate between low and high frequencies—for example, 2 hertz and 100 hertz every few seconds.

The science is also zeroing in on how electroacupuncture might regulate inflammation and stress responses. In one 2021 paper, researchers pinpointed a subset of sensory neurons that need to be present for acupuncture to trigger an anti-inflammatory response. They mapped a reflex pathway from these neurons through the vagus nerve to the adrenal gland, linking peripheral stimulation to systemic immune regulation (29).

Given the growing areas of overlap, Napadow urges acupuncture researchers to partner with scientists in bioelectronic medicine, where the vagus nerve is a central target (30). This long nerve connects the brain to organs, such as the heart, lungs, pancreas, and intestines, and helps regulate functions like breathing and heart rate. Implanted or external devices that stimulate a branch of the vagus nerve at the ear or neck have shown promise in easing symptoms of rheumatoid arthritis, heart disease, inflammatory bowel disease, and other conditions—leading some to view them as a modern form of acupuncture.

Ear acupoints, for instance, also engage the vagus nerve. “People have been doing acupuncture on the ear forever,” Langevin says. It’s an easy and cost-efficient delivery method, allowing a practitioner to treat groups of people simultaneously. Since the 1970s, various programs have brought this simplified acupuncture treatment to detox programs, homeless populations, disaster relief, and prisons for stress, trauma, and addiction treatment (31, 32). The US Army, too, uses ear acupuncture to help deployed soldiers manage pain, migraines, anxiety, and stress (33).

With big data and artificial intelligence rapidly advancing, Napadow says that machine-learning models could be trained to determine which acupoints are most effective for specific conditions, and wearable sensors could track responses over time to speed research and improve clinical practice. He laments that the field has been slow to translate new scientific insights. “Basic scientists need to connect what they do with clinical research. The other way, too.”

Government funding for acupuncture research is still largely confined to pain, Napadow adds, limiting progress in other areas. “We need more clinical trials in other disorders, but those studies are not as readily supported.”

Chen cautions that while modern medical explanations of acupuncture mechanisms have significantly enhanced public understanding and trust, the science may never tell the whole story. “This isn’t necessarily spiritual or mystical,” she says. “Rather, current biomedical tools don’t yet capture the full complexity of what happens in the body during acupuncture.”

That gap reflects different ways of approaching the body; the West favors reducing it to its parts, and the East views it as an integrated whole. As Theise puts it, “We now have an anatomy that allows us to make sense of acupuncture in Western terms.” Traditional practitioners don’t need that framework, he says, “but they want to communicate with us, just as we want to figure out if they’re making this up.” The convergence, he suggests, could expand both ways of seeing.