BL-25 (Da Chang Shu) Large Intestine Shu

What does BL-25 Da Chang Shu do?

Da Chang Shu BL-25 is the Back-Shu point of the Large Intestine, and in modern practice it is also one of the two or three most-used points in the whole of low back treatment. Sacred Lotus sources & references record that classification directly. It gives the point a double character that is unusual even among the Back-Shu points: by classification it reaches the large bowel, and by position — level with the fourth lumbar vertebra, in the thick of the lumbar muscles — it is a local point for exactly the segment of spine where most low back pain and most disc herniation occur.

• Regulates the intestines — the defining action, recorded first in our own action record. As with every Back-Shu point, "regulates" is meant literally and in both directions: BL-25 appears in prescriptions for constipation and for diarrhoea alike, and the technique and partner points decide which way the treatment runs.
• Transforms stagnation and alleviates pain — for abdominal distension, borborygmus and the griping, blocked abdominal pain the tradition attributes to stagnation in the bowel.
• Strengthens the lumbar region and legs — the local action, and the one that accounts for most of the point's modern use. It is applied to lumbar pain and stiffness, to sciatic pain running down the leg, and to weakness, numbness and wasting of the lower limb.
• Dispels damp-heat from the lower burner — the reasoning behind its recorded use in dysentery-type diarrhoea and in the hot, urgent, foul-smelling bowel presentations.
• Serves as a diagnostic point — like all Back-Shu points, tenderness, a sunken quality or a temperature change at BL-25 is read as a sign that its organ or its segment is involved. That is not only tradition: infrared thermography in patients with disc-related low back pain found the affected side measurably warmer than the healthy side at BL-25 and at BL-23, and singled out those two points as showing relative specificity (PMID 38621730).

Why the two halves of this point do not contradict each other. Readers sometimes ask how a bowel point ends up being the first choice for a bad back. The classical answer is that the Back-Shu point is where the organ's qi infuses the surface, and the surface it infuses is the lower back; the anatomical answer is that BL-25 sits at the L4 level, over the muscles that fail in lumbar strain and beside the nerve roots that produce sciatic pain. Both readings put the same point in the same place, and the modern literature has followed the local reading much further than the visceral one.

Source: Sacred Lotus sources & references (channel and Back-Shu classification; existing action record); Deadman & Al-Khafaji, A Manual of Acupuncture (p. 286); Chinese Acupuncture & Moxibustion (p. 181); PubMed PMID 38621730; cross-referenced against multiple online sources.

What is BL-25 Da Chang Shu used for?

Da Chang Shu BL-25 is used above all for low back pain and sciatica, and secondarily for the bowel disorders its Back-Shu classification points to — diarrhoea, constipation, abdominal distension and borborygmus. The indications below are those carried in Sacred Lotus sources & references together with those set out in the standard reference literature. They describe traditional use, not proven treatment.

• Low back pain and lumbar stiffness
• Sciatica and pain radiating into the leg
• Pain, numbness and motor impairment of the lower extremities
• Muscular atrophy and weakness of the legs
• Diarrhoea
• Constipation
• Dysentery
• Abdominal distension and abdominal pain
• Borborygmus (rumbling of the intestines)
• Undigested food in the stool
• Difficulty in urination and enuresis, in the wider reference literature
• Intestinal abscess and haemorrhoidal complaints, in the classical record

Constipation and diarrhoea sitting on the same list is not an error. It is how Back-Shu points behave: the point is chosen because the organ is implicated, and the direction of the treatment is set elsewhere.

Source: Sacred Lotus sources & references (existing indication record); Deadman & Al-Khafaji, A Manual of Acupuncture (p. 286); Chinese Acupuncture & Moxibustion (p. 181); cross-referenced against multiple online sources.

Where is BL-25 Da Chang Shu, and how is it used in practice?

Da Chang Shu lies on the lower back, one and a half cun either side of the midline, level with the lower edge of the fourth lumbar vertebra — that is, level with Yao Yang Guan DU-03 on the spine itself. Sacred Lotus sources & references give it in both terms: one and a half cun lateral to DU-03, and one and a half cun lateral to the lower border of the L4 spinous process. It is a bilateral point. A useful landmark is that a line drawn across the back between the highest points of the two iliac crests passes close to the L4 spinous process, which is why BL-25 is one of the easier back points to find reliably on a range of body types.

In practice BL-25 is used far more often as a lumbar point than as a bowel point. That is not a distortion of the tradition so much as a reflection of what walks through a modern clinic door: a data-mining analysis of 537 published studies of acupuncture for lumbar disc herniation, covering 766 distinct prescriptions and 149 different points, found BL-25 to be the third most frequently selected point of all, after BL-40 Wei Zhong and GB-30 Huan Tiao, and identified the BL-40 with BL-25 pairing as the single strongest association rule in the whole dataset (PMID 41804332). The Bladder channel accounted for more than half of all point selections in that analysis.

Which points is BL-25 combined with?

• With ST-25 Tian Shu — the Shu-Mu combination for the Large Intestine: the Back-Shu point behind, the Front-Mu point in front, one organ approached from both faces of the body. This is the oldest structured pairing in the medicine, and it is the pairing that most of the modern laboratory work on BL-25 actually uses.
• With ST-37 Shang Ju Xu — the Lower He-Sea point of the Large Intestine below the knee, completing the classical Shu, Mu and Lower He-Sea approach to one bowel.
• With BL-40 Wei Zhong — the Command point of the back, at the back of the knee. The most frequent pairing in the published low-back literature and the standard local-plus-distal structure for lumbar pain.
• With BL-26 Guan Yuan Shu — the next point down the inner Bladder line at L5. BL-25 and BL-26 together were the obligatory bilateral points in the multicentre sham-controlled sciatica trial described below.
• With GB-30 Huan Tiao and GB-34 Yang Ling Quan — where the pain refers down the outside of the leg; GB-34 is the Hui-Meeting point of the sinews.
• With DU-03 Yao Yang Guan — the Governing Vessel point directly medial at the same level, the natural centre of a local lumbar treatment.
• With BL-23 Shen Shu — one level above at L2, added where the low back complaint is chronic, weak and attributed to Kidney depletion rather than to local strain.
• With the extra points Yao Yan and Shi Qi Zhui Xia — both held in Sacred Lotus sources & references, and both local points of the same lumbar region; Yao Yan sits further out at the same L4 level, Shi Qi Zhui Xia on the midline just below.

Where does BL-25 sit among the Back-Shu points?

The Back-Shu points run down the inner Bladder line, one and a half cun either side of the spine, one for each organ, in roughly the order the organs sit in the trunk. Sacred Lotus sources & references hold the complete set of twelve:

• Fei Shu BL-13 — Lungs
• Jue Yin Shu BL-14 — Pericardium
• Xin Shu BL-15 — Heart
• Gan Shu BL-18 — Liver
• Dan Shu BL-19 — Gallbladder
• Pi Shu BL-20 — Spleen
• Wei Shu BL-21 — Stomach
• San Jiao Shu BL-22 — San Jiao
• Shen Shu BL-23 — Kidneys
• Da Chang Shu BL-25 — Large Intestine
• Xiao Chang Shu BL-27 — Small Intestine
• Pang Guang Shu BL-28 — Bladder

Each Back-Shu point pairs with its organ's Front-Mu point on the front of the trunk, and Sacred Lotus sources & references hold that set of twelve too: LU-01 Zhong Fu for the Lungs, REN-17 Shan Zhong for the Pericardium, REN-14 Ju Que for the Heart, LIV-14 Qi Men for the Liver, GB-24 Ri Yue for the Gall Bladder, LIV-13 Zhang Men for the Spleen, REN-12 Zhong Wan for the Stomach, REN-05 Shi Men for the San Jiao, GB-25 Jing Men for the Kidneys, ST-25 Tian Shu for the Large Intestine, REN-04 Guan Yuan for the Small Intestine and REN-03 Zhong Ji for the Bladder. BL-25's own partner is therefore ST-25, two cun to the side of the navel — a point on the Stomach channel collecting the qi of the Large Intestine, which is the clearest reminder that Front-Mu points are assigned by anatomy rather than by channel.

Two features of the numbering are worth noticing. First, there is a gap: BL-24 Qi Hai Shu sits between BL-23 and BL-25 but is not a Back-Shu point of an organ at all — it is named as the back counterpart of Qi Hai REN-06. The same is true of BL-26 Guan Yuan Shu below. Second, the Large Intestine and Small Intestine Back-Shu points sit low on the back, at L4 and S1, well below the organs they name. Their position follows the classical scheme rather than gross anatomy, and it is one of the places where the Back-Shu arrangement stops being a simple map of the torso.

Source: Sacred Lotus sources & references (BL-25 record; the full twelve-point Back-Shu set and the twelve Front-Mu points queried directly; DU-03, BL-26, BL-40, GB-30, GB-34, ST-25, ST-37, Yao Yan and Shi Qi Zhui Xia records); Deadman & Al-Khafaji, A Manual of Acupuncture (p. 286); Chinese Acupuncture & Moxibustion (p. 181); PubMed PMID 41804332 (PMC12967424); cross-referenced against multiple online sources.

Where is BL-25 located?

• A Manual of Acupuncture (p. 286): 1.5 cun lateral to the lower border of the spinous process of the fourth lumbar vertebra (L4).
• Chinese Acupuncture and Moxibustion (p. 181): 1.5 cun lateral to Yaoyangguan (DU-3), at the level of the lower border of the spinous process of the fourth lumbar vertebra.

How is BL-25 Da Chang Shu needled, and what lies beneath it?

Stated plainly and precisely: BL-25 is a lumbar point at the level of the fourth lumbar vertebra. The kidneys lie retroperitoneally, spanning roughly the twelfth thoracic to the third lumbar vertebral levels — so BL-25 sits at or just below the lower margin of that span, not in the middle of it as BL-23 does at L2. That distinction matters, and this record makes it rather than importing the kidney caution wholesale from the points above. Everything below is recorded as neutral reference data describing what the textbooks and the published studies state. It is not instruction, and this page does not teach technique. Needling is carried out only by a qualified, licensed practitioner.

The angle and depth the texts record

• Sacred Lotus sources & references record perpendicular insertion of 0.8 to 1.2 inch, with moxibustion applicable.
• Deadman & Al-Khafaji (p. 286) and Chinese Acupuncture & Moxibustion (p. 181) record a comparable perpendicular range, with oblique insertion angled medially toward the spine also described, and moxibustion noted as applicable.
• Measured depth in a major trial. The multicentre randomised sham-controlled trial of acupuncture for chronic sciatica from herniated disc published in JAMA Internal Medicine used bilateral BL-25 and BL-26 as its obligatory points and specified insertion at those two points to a depth of approximately 30 to 40 mm, with needles retained for 30 minutes (Tu JF et al., JAMA Intern Med 2024;184(12):1417–1424, PMID 39401008, PMC11581490). This is unusually useful: a figure recorded for BL-25 itself, in a registered protocol, in a trial that reported no serious adverse events across 216 patients and ten sessions each.

What actually lies deep to this point

• The tissue in order. At L4, one and a half cun from the midline, a perpendicular needle passes through skin and the thoracolumbar fascia into the erector spinae muscle mass, and deeper still toward quadratus lumborum and the transverse process region. This is the thickest paraspinal muscle territory on the trunk, which is why the reference depth at BL-25 is greater than at most points on the body.
• Where the kidneys are, and are not. The kidneys are retroperitoneal, lying against the posterior abdominal wall in front of the lumbar muscles, at roughly T12 to L3, with the right kidney sitting slightly lower than the left because of the liver above it. BL-25 at L4 is therefore below the usual renal span. The honest qualification is that this is a statement about the average body: the lower pole of the right kidney reaches lowest, normal variation extends further down, and a ptotic or congenitally low-lying kidney sits lower again. So the accurate framing at BL-25 is that the standard renal caution attached to BL-21, BL-22 and BL-23 applies here with less force than it does there — not that the region beneath is muscle all the way down.
• The measured evidence, and whose point it measured. An MRI study of 61 healthy subjects measured both the "dangerous depth" and the effective safe depth of perpendicular and oblique needling at the acupoints of the kidney region — Wei Shu BL-21, San Jiao Shu BL-22, Shen Shu BL-23, Wei Cang BL-50, Huang Men BL-51 and Zhi Shi BL-52. Dangerous and safe depths were significantly greater in overweight subjects than in moderate-weight ones, and greater again than in underweight subjects, where the authors concluded that direction and depth must be restricted to avoid accident (Chen GT et al., Zhongguo Zhen Jiu 2022;42(9):1006–1010, PMID 36075596). That study did not measure BL-25. Its points sit higher in the lumbar region. We cite it because it is the best-quantified evidence that safe depth in the lumbar region is a function of the individual body rather than a fixed number — not as a measurement of this point.
• What the case literature documents for the region. Injury to retroperitoneal structures following acupuncture appears in the published case literature, including a retroperitoneal haematoma from rupture of a pseudoaneurysm caused by acupuncture (J Urol 1998;159(6):2087, PMID 9598531) and a retroperitoneal abscess complicating acupuncture (J Korean Med Sci 2003;18(5):756–757, PMID 14555834). Systematic reviews of acupuncture adverse events list traumatic organ injury among the small number of genuinely serious events on record and conclude that these overwhelmingly followed improper technique rather than acupuncture as such (Zhang et al., Bull World Health Organ 2010;88(12):915–921C, PMID 21124716, PMC2995190; Am J Chin Med 2024, PMID 39460372).
• Honest limit of what we can source. We could not locate a published case report naming BL-25 specifically in connection with an organ injury. Rather than assert one or drop the subject, what is recorded here is what is documented: a bounded depth in the reference texts, a measured 30–40 mm protocol depth in a large registered trial at this exact point, the anatomical position of BL-25 relative to the renal span, and a published record of retroperitoneal injury from deep needling in this general region.

The proportion of the risk

A meta-analysis of prospective clinical studies estimated serious adverse events in acupuncture at approximately 1 per 10,000 patients and around 8 per million treatments (Bäumler P et al., BMJ Open 2021;11:e045961, PMID 34489268). Against that background it is worth recording that the sciatica trial above — 216 patients, ten sessions each, BL-25 needled bilaterally at 30–40 mm every time — reported no serious adverse events (PMID 39401008). The bounded depth exists to keep it that way.

Source: Sacred Lotus sources & references (existing needling record); Deadman & Al-Khafaji, A Manual of Acupuncture (p. 286); Chinese Acupuncture & Moxibustion (p. 181); PMID 39401008 (PMC11581490); PMID 36075596; PMID 9598531; PMID 14555834; PMID 21124716 (PMC2995190); PMID 39460372; PMID 34489268 — each verified resolvable and checked for retraction status before citation.

What does the name Da Chang Shu mean?

Da Chang Shu means "Large Intestine Shu" — da chang, the large intestine, and shu, a transport point. The character shu carries the sense of conveying or transporting, and the Back-Shu points are named for exactly that: the places on the back where each organ's qi is said to be transported to the body surface. Sacred Lotus sources & references translate the name as Large Intestine Shu and classify the point as the Back-Shu of the Large Intestine. Like the other eleven, the name is a plain description of function rather than a metaphor, which is why the Back-Shu points are the easiest set of names in acupuncture to learn.

Why does the Back-Shu classification matter at BL-25?

The Back-Shu points are the tradition's most direct route to an internal organ. Each is understood as the place where that organ's qi infuses the back, which gives them two roles: they are used to treat the organ, particularly in chronic conditions, and they are palpated in diagnosis, since tenderness or a change in the tissue at a Back-Shu point is read as a sign that its organ is involved. Pairing a Back-Shu point with the matching Front-Mu point is the classical Shu-Mu combination, and at BL-25 that partner is ST-25 Tian Shu.

BL-25 is nonetheless an instructive case of a point whose modern life has outgrown its classification. The classical rationale for using it is that it reaches the large bowel. The reason most practitioners actually reach for it is that it sits at L4, in the middle of the segment where lumbar disc herniation and lumbar strain occur, beside the nerve roots that generate sciatic pain. Both are legitimate, and a reader should know that the two are different arguments.

Is there research on BL-25 Da Chang Shu?

BL-25 is one of the better-evidenced points on the back, because it was an obligatory point in a large, well-conducted, sham-controlled trial published in a major general medical journal. That is rare in acupuncture research and worth separating carefully from the weaker material around it.

• Multicentre randomised sham-controlled trial, BL-25 as an obligatory point. 216 patients with chronic sciatica from herniated disc were recruited across six tertiary hospitals in China and randomised to ten sessions of acupuncture or sham acupuncture over four weeks, with participants, outcome assessors and statisticians blinded. Bilateral BL-25 Da Chang Shu and BL-26 Guan Yuan Shu were the obligatory points in every treatment, with five further points chosen from a fixed list according to whether the pain ran down the back or the outside of the leg. Leg pain on a visual analogue scale fell by 30.8 mm with acupuncture against 14.9 mm with sham (mean difference −16.0 mm), and the Oswestry Disability Index fell by 13.0 against 4.9 points (mean difference −8.1); the separation appeared from week 2 and persisted to week 52. No serious adverse events occurred (Tu JF et al., JAMA Intern Med 2024;184(12):1417–1424, PMID 39401008, PMC11581490). Two honest qualifications: BL-25 was one of seven points used in each session, so this is evidence for a protocol built on BL-25 rather than for BL-25 in isolation; and sham acupuncture in trials of this kind is not an inert placebo.
• Secondary analysis of the same trial. Splitting the 216 patients by body mass index found acupuncture superior to sham in both the normal-weight and the overweight/obese subgroups, with no interaction between body mass index and treatment effect (Zhongguo Zhen Jiu 2026;46(4):559–564, PMID 41987443). Useful mainly because it confirms the protocol — bilateral Dachangshu BL-25 and Guanyuanshu BL-26 as main points — and because body size is otherwise the variable that most affects needling at this depth.
• Point specificity, measured. Infrared thermography in 50 patients with low back pain from lumbar disc herniation and 45 healthy controls measured surface temperature at BL-22 through BL-28. Left-right temperature differences at BL-23, BL-24, BL-25, BL-26 and BL-27 were greater in the patients than in the controls, and within the patient group the affected side was warmer than the healthy side at the lumbosacral region and at BL-23 and BL-25 specifically — the authors concluded that those two points showed relative specificity (Zhongguo Zhen Jiu 2024;44(4):423–427, PMID 38621730). This is evidence that the point behaves differently under pathological conditions, not evidence of treatment effect.
• Point-selection evidence. A data-mining analysis of 537 studies of acupuncture for lumbar disc herniation, comprising 766 prescriptions and 149 distinct points, found thirteen core points accounting for 74.65% of all usage, with BL-40 Wei Zhong (9.68%), GB-30 Huan Tiao (8.47%) and BL-25 Da Chang Shu (8.30%) the three most frequently used; the BL-40 with BL-25 pair was the strongest association rule found, with 42.43% support (J Pain Res 2026;19:576514, PMID 41804332, PMC12967424). That is evidence about what practitioners and trialists choose, not about what the point achieves.
• Laboratory work on the bowel side. The visceral literature on BL-25 is animal work, and it almost always uses the Shu-Mu pair rather than BL-25 alone. Electroacupuncture at ST-25 and BL-25 reduced visceral hypersensitivity in rats with post-inflammatory irritable bowel syndrome, with transcriptome sequencing pointing to chemokine-pathway genes including CXCL10, CCL20 and CXCR4 (Zhongguo Zhen Jiu 2026;46(6):970–978, PMID 42343522); electroacupuncture at the same Front-Mu and Back-Shu pair improved intestinal transit in a rat model of slow-transit constipation, with effects attributed to reduced excessive autophagy of the interstitial cells of Cajal (Zhongguo Zhen Jiu 2026;46(7):1136–1145, PMID 42443084). Both are rat studies of a two-point protocol.
• A retraction, recorded openly. A 2022 paper in Evidence-Based Complementary and Alternative Medicine on the efficacy of BL-25 and ST-25 in childhood functional constipation was retracted by the journal in 2023 (retraction notice: Evid Based Complement Alternat Med 2023;2023:9876529, PMID 37808143, retracting DOI 10.1155/2022/5315927). It still circulates in search results and is excluded here. The same paper was excluded from our ST-25 record for the same reason.

What is missing should be said plainly: there is no trial of BL-25 as a single point against a credible control, and the strong evidence that exists concerns a seven-point sciatica protocol in which BL-25 is the anchor. The bowel claims that follow from its Back-Shu classification rest on classical authority and animal work, not on human trials of this point.

How does BL-25 compare with the points around it?

BL-23 Shen Shu lies two levels above at L2 and is the Back-Shu point of the Kidneys — the choice when the low back is weak, chronic and cold rather than acutely strained, and the point that genuinely carries the "tonifies the Kidneys" action. BL-24 Qi Hai Shu at L3 and BL-26 Guan Yuan Shu at L5 are BL-25's immediate neighbours on the inner line; neither is an organ Back-Shu point, both being named as back counterparts of the abdominal points Qi Hai REN-06 and Guan Yuan REN-04. BL-27 Xiao Chang Shu below on the sacrum is the Small Intestine Back-Shu point. DU-03 Yao Yang Guan is directly medial on the midline at the same L4 level. ST-25 Tian Shu on the abdomen is BL-25's Front-Mu counterpart, and ST-37 Shang Ju Xu below the knee is the Lower He-Sea point of the same organ. Yao Yan, the extra point in the visible hollows of the lower back, sits further out at about three and a half cun at the same level — a local point of the region, with no channel and no organ classification. And BL-40 Wei Zhong, behind the knee, is BL-25's constant distal partner and the Command point of the back.

Source: Sacred Lotus sources & references (name, Back-Shu classification and the cross-referenced point records above); Deadman & Al-Khafaji, A Manual of Acupuncture (p. 286); Chinese Acupuncture & Moxibustion (p. 181); PubMed PMID 39401008 (PMC11581490), 41987443, 38621730, 41804332 (PMC12967424), 42343522, 42443084, and retraction notice PMID 37808143 — each verified resolvable and checked for retraction status before citation; cross-referenced against multiple online sources.