BL-23 (Shen Shu) Kidney Shu

What does BL-23 Shen Shu do?

Shen Shu BL-23 is the Back-Shu point of the Kidneys and the principal Kidney-tonifying point of the body. Sacred Lotus sources & references record that classification directly, and it is the single fact that organises everything else about this point: the Back-Shu points are the places on the back where each organ's qi is said to infuse the surface, and BL-23 is the Kidneys'. Where a treatment intends to supplement the Kidneys — yin, yang, qi or essence — BL-23 is very rarely absent from it.

• Tonifies the Kidneys and fortifies yang — the defining action, recorded first in our own action record. Used for the cold, depleted, weak-lower-back presentation the tradition attributes to Kidney yang deficiency, and for the reproductive complaints that accompany it.
• Nourishes Kidney yin — the same point supplements the other side of the pair, for heat from deficiency, night sweats, dryness and restlessness. That a single point is used for both yin and yang deficiency is characteristic of the Back-Shu points: they reach the organ rather than a particular aspect of it.
• Benefits essence (jing) — the constitutional substance the Kidneys are said to store, underlying growth, development, fertility and ageing. This is the theoretical basis for the point's long-standing use in developmental, reproductive and premature-ageing complaints.
• Firms Kidney qi — for qi that fails to hold: nocturnal emission, enuresis, urinary frequency and incontinence, chronic vaginal discharge.
• Regulates the water passages and benefits urination — the Kidneys govern water in classical theory, and BL-23 is used for oedema and for difficult or excessive urination.
• Benefits and warms the uterus — for menstrual irregularity, infertility and cold in the lower abdomen attributed to Kidney depletion.
• Benefits the ears and the eyes — the classical correspondences: the Kidneys are said to open into the ears, which is the reasoning behind the point's recorded use for tinnitus, deafness, blurred vision and dizziness.
• Strengthens the lumbar region — the local action. BL-23 sits in the middle of the lower back, and it is used for lumbar pain and weakness both as a local point and as a tonifying one, since the tradition regards the lower back as "the residence of the Kidneys".

Source: Sacred Lotus sources & references (existing action record; Back-Shu classification); Deadman & Al-Khafaji, A Manual of Acupuncture (p. 283); Chinese Acupuncture & Moxibustion (p. 180); cross-referenced against multiple online sources.

What is BL-23 Shen Shu used for?

Shen Shu BL-23 is used for low back pain and weakness, and for the reproductive, urinary, ear and eye complaints that classical theory attributes to depleted Kidneys. 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, and this point carries the depth cautions set out under needling.

• Low back pain, lumbar ache and stiffness
• Weakness of the knees and legs
• Nocturnal emission and impotence
• Enuresis, urinary frequency and incontinence
• Irregular menstruation and infertility
• Leukorrhoea
• Blurring of vision and dimness of sight
• Dizziness
• Tinnitus and deafness
• Oedema and difficult urination
• Chronic asthma and wheezing with weak breathing on exertion
• Chronic diarrhoea, especially before dawn
• Fatigue, cold limbs and general depletion

Source: Sacred Lotus sources & references (existing indication record); Deadman & Al-Khafaji, A Manual of Acupuncture (p. 283); Chinese Acupuncture & Moxibustion (p. 180).

Where is BL-23 Shen Shu, and how is it used in practice?

Shen Shu lies on the lower back, one and a half cun either side of the midline, level with the lower edge of the second lumbar vertebra — that is, level with Ming Men DU-04 on the spine itself. Sacred Lotus sources & references give it in both terms: one and a half cun lateral to Ming Men DU-04, and one and a half cun lateral to the lower border of the L2 spinous process. It is a bilateral point, needled on both sides, and it sits in the belly of the muscle mass either side of the spine at the narrowest part of the waist.

In practice BL-23 is one of the small number of points used in almost every kind of case, because Kidney depletion is implicated in so much of the classical pathology of ageing, chronic illness and reproduction. It is very commonly treated with moxibustion or warm-needle technique rather than needling alone, since most of what it is used for is deficiency and cold.

Which points is BL-23 combined with?

• With Ming Men DU-04 — directly medial to it on the Governing Vessel at the same level; the pairing of the Kidney Back-Shu points with the "Life Gate" is the standard structure for warming Kidney yang.
• With Tai Xi KI-03 — the Yuan-Source point of the Kidney channel at the ankle. Back-Shu with Yuan-Source is a classical pairing for supplementing an organ, and this is its Kidney instance.
• With Guan Yuan REN-04 and Qi Hai REN-06 — the great lower-abdominal tonification points on the front of the body, giving a front-and-back treatment of the lower burner.
• With Zhi Shi BL-52 — "Will Chamber", on the outer Bladder line three cun lateral at the same L2 level, the outer companion of BL-23 and the point associated with the will (zhi) that the Kidneys are said to house.
• With San Yin Jiao SP-06 — for gynaecological and urinary complaints, adding the meeting point of the three leg yin channels.
• With Da Chang Shu BL-25 and the local lumbar points — for low back pain treated as a local problem; BL-25 lies one level below at L4.
• With Fei Shu BL-13 — for chronic wheezing, on the classical reasoning that the Lungs govern the intake of qi and the Kidneys its grasping; the pairing appears in the published point-application and moxibustion work on asthma.

Where does BL-23 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, and they are worth seeing together because the arrangement is the point:

• 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. The Kidneys' Front-Mu is Jing Men GB-25 on the flank at the free end of the twelfth rib — which surprises people, since it is not on the Kidney channel at all. Front-Mu points frequently sit on a different channel from their organ, and the Kidneys are the clearest example. BL-23 is by some distance the most used of the twelve, because Kidney deficiency is the pattern most often treated.

Source: Sacred Lotus sources & references (BL-23 record; the full twelve-point Back-Shu set and the twelve Front-Mu points queried directly); Deadman & Al-Khafaji, A Manual of Acupuncture (p. 283); Chinese Acupuncture & Moxibustion (p. 180); cross-referenced against multiple online sources.

Where is BL-23 located?

• A Manual of Acupuncture (p. 283): 1.5 cun lateral to the lower border of the spinous process of the second lumbar vertebra (L2).
• Chinese Acupuncture and Moxibustion (p. 180): 1.5 cun lateral to Mingmen (DU-4), at the level of the lower border of the spinous process of the second lumbar vertebra.

How is BL-23 Shen Shu needled, and what lies beneath it?

Stated plainly: BL-23 lies in the lumbar region at the level of the second lumbar vertebra, and the kidneys lie retroperitoneally — behind the abdominal cavity and in front of the lumbar muscles — spanning roughly the twelfth thoracic to the third lumbar vertebral levels. BL-23 is therefore over the kidney region, and the depth recorded in the texts is bounded for that reason. Everything below is recorded as neutral reference data describing what the textbooks and the published imaging 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 1 to 1.2 inch, with moxibustion applicable.
• Deadman & Al-Khafaji (p. 283) and Chinese Acupuncture & Moxibustion (p. 180) record a comparable perpendicular range and both attach a caution against deep insertion in the lumbar region because of the kidney lying beneath. Oblique insertion angled medially toward the spine is also recorded.
• Moxibustion is recorded as applicable and is the technique most associated with this point, which is used overwhelmingly for deficiency and cold.

The measured anatomy — what has actually been quantified

• MRI measurement of safe depth at BL-23 itself. 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. Left and right sides did not differ. What did differ, substantially, was body size: dangerous and safe depths were significantly greater in the overweight group than in the moderate group, and greater in the moderate group than in the underweight group. The authors' conclusion was that in underweight patients the direction and depth of needling must be restricted to avoid accident (Chen GT et al., Zhongguo Zhen Jiu 2022;42(9):1006–1010, PMID 36075596, DOI 10.13703/j.0255-2930.20210820-k0007). This is the single most useful measured finding for this point, and its practical content is that a textbook depth figure is a description of an average body, not a constant.
• Cadaveric measurement of what a needle reaches. A dissection study inserted a depth-measuring blade perpendicularly at BL-23 in twelve dissected specimens to establish whether the psoas major muscle — the deep muscle of the lumbar spine, and one implicated in low back pain — can be reached from this point. Half the insertions reached psoas. The mean depth required was 38.0 mm (interquartile range 29.0–51.8 mm) in specimens with short-term underlying conditions and about 6 mm less, at 32.0 mm (29.3–42.5), in those with long-term health problems, the difference tracking a roughly 1.5-fold difference in the cross-sectional area of the muscle. Depth to psoas correlated negatively with body length (Chia KL, Haberberger RV, J Integr Med 2016;14(2):128–33, PMID 26988434, DOI 10.1016/S2095-4964(16)60246-7). Read alongside the MRI work, it says the same thing from a different direction: what a given depth reaches at this point depends on the individual body.
• Where the kidneys actually are. The kidneys are retroperitoneal, lying against the posterior abdominal wall behind the peritoneum and in front of the lumbar muscles, at roughly the T12–L3 levels, with the right kidney sitting slightly lower than the left because of the liver above it. BL-23 at L2 is in the middle of that span rather than at its edge — which is the honest statement, and the reason the kidney is named explicitly in the standard cautions for this point where it is not for the lower lumbar points.
• What the case literature documents. Injury to retroperitoneal structures following acupuncture is recorded 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).
• Honest limit of what we can source. We could not locate a published case report naming BL-23 specifically as the point at which a kidney injury occurred. Rather than assert one or omit the subject, what is recorded here is what is documented: a bounded depth in the reference texts, imaging and cadaveric evidence that safe depth at this exact point varies markedly with body size, the anatomical fact that the kidney lies within the L2 span, and a published record of retroperitoneal injury from deep needling in this 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, placing it among the safer treatments in medicine (Bäumler P et al., BMJ Open 2021;11:e045961, PMID 34489268, DOI 10.1136/bmjopen-2020-045961). Notably, the randomised double-blind sham-controlled trial of BL-23 needling described under research reported no adverse events associated with acupuncture at this point (PMID 37542799). 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. 283); Chinese Acupuncture & Moxibustion (p. 180); PMID 36075596; PMID 26988434; PMID 9598531; PMID 14555834; PMID 21124716 (PMC2995190); PMID 34489268; PMID 37542799 — each verified resolvable and checked for retraction status before citation.

What does the name Shen Shu mean?

Shen Shu means "Kidney Shu" — shen, the Kidneys, 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 Kidney Shu and classify the point as the Back-Shu of the Kidneys. The name is a description of the point's function rather than a metaphor, which sets it apart from most of the repertoire — and it is the reason the twelve Back-Shu points are among the easiest names in acupuncture to learn.

Why does the Back-Shu classification matter?

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 and deficient conditions, and they are palpated in diagnosis, since tenderness, a sunken feeling or a change in the tissue at a Back-Shu point is read as a sign that its organ is involved. BL-23 is the most heavily used of the twelve for a straightforward reason — the Kidneys, in classical theory, hold the body's constitutional reserve, and their depletion is the pattern behind a very large share of chronic complaints, ageing, reproductive difficulty and lower-back weakness. Back-Shu points are also strongly associated with moxibustion, which is why so much of the modern research on BL-23 uses moxa rather than needles.

Is BL-23 the point that "tonifies the Kidneys"?

Yes — and it is worth saying so explicitly, because the phrase attaches itself to other points that do not carry it. A number of points in the lumbar region are described in circulating material as tonifying the Kidneys on the strength of where they sit rather than what they are. The extra point Yao Yan, in the visible hollows of the lower back, is the clearest example: it lies in the region the tradition associates with the Kidneys and its documented uses are the ones a practitioner would attribute to Kidney depletion, but it is on no channel, carries no Back-Shu or other classification, and has no channel connection to the Kidney organ. Our own record for Yao Yan previously carried the claim and it has been removed; the action belongs to BL-23 Shen Shu, which holds the Back-Shu classification that gives it. This page is the other half of that correction. A reader who arrived searching for "the point that tonifies the Kidneys" has arrived at the right one.

Is there research on BL-23 Shen Shu?

BL-23 has more point-specific research attached to it than almost any other Back-Shu point, including a randomised double-blind sham-controlled human trial of the point alone and the first single-cell study ever performed at a human acupuncture point.

• Randomised double-blind sham-controlled trial. Sixteen healthy adults were randomised to acupuncture at BL-23 or to pseudo-acupuncture, with serum cytokines measured before and after. Changes in IL-13, TNF-α and GM-CSF differed between the groups (P < 0.05); the authors concluded that BL-23 acupuncture suppressed immune responses through a decrease in TNF-α and suppression of rises in IL-13 and GM-CSF, and recorded no adverse events (Murakami E et al., J Neuroimmunol 2023;382:578165, PMID 37542799, DOI 10.1016/j.jneuroim.2023.578165). It is a phase-1 study in sixteen people — small, and a mechanistic signal rather than a clinical result — but the design is the right one and the point tested is this point alone. A published comment on it appeared in the same journal.
• Single-cell transcriptomics at the point itself. A UCLA-led group developed a technique for collecting cells from the acupuncture needle during treatment and used it to characterise, for the first time, what is happening cellularly at a human acupoint. At BL-23 in people with low back pain they identified eight cell types — inflammatory fibroblast, myofibroblast, skeletal muscle cell, endothelial cell, smooth muscle cell, adipocyte, macrophage, and a previously undescribed cell type marked by CNTNAP2 and CSMD1. That novel population was significantly enriched during the pain-relief phase while the other seven types fell, and its transcriptional profile pointed to synapse assembly and synaptic plasticity (Zhao G et al., Mol Pain 2025;21:17448069251405974, PMID 41312958, PMC12743158, DOI 10.1177/17448069251405974). BL-23 was the point chosen for this first-of-its-kind work, which is itself a comment on the point's clinical standing.
• Autonomic and renin response, with a sham control. Eight healthy volunteers underwent three conditions in random order — control, stimulation at Shenshu BL-23, and stimulation at a sham point — while standing, a posture that raises sympathetic activity. The low-frequency/high-frequency heart-rate-variability ratio rose in the control and sham conditions but not after BL-23 stimulation, with plasma renin concentration measured alongside (Umemoto K et al., J Tradit Chin Med 2022;42(2):250–255, PMID 35473346, DOI 10.19852/j.cnki.jtcm.2022.02.005). Very small, but sham-controlled and specific to this point.
• Moxibustion at BL-23 in perimenopausal women. Sixty participants were randomised to mild moxibustion at bilateral Shenshu BL-23 for fifteen minutes daily or to oral vitamin E for 28 days. Quality-of-life scores improved in both groups and more so with moxibustion (P < 0.05); serum oestradiol, progesterone and anti-Müllerian hormone rose in the moxibustion group, while inhibin B did not change (Zhongguo Zhen Jiu 2017;37(4):381–385, PMID 29231589, DOI 10.13703/j.0255-2930.2017.04.008). Single-centre and unblinded, with an active rather than placebo comparator — but a trial of moxibustion at this point on its own.
• Review of the point. A dedicated review of the research literature on Shenshu BL-23 has been published (Zhongguo Zhen Jiu 2017;37(8):845–850, PMID 29231345), and BL-23 recurs as a high-frequency point in modern point-selection analyses — for example among the ten most-selected points across 85 included studies of acupuncture for benign prostatic hyperplasia (Medicine (Baltimore) 2025;104(32):e43802, PMID 40797416, PMC12338299).
• Animal work. A large preclinical literature moxibusts BL-23 with Zu San Li ST-36 in models of rheumatoid arthritis, osteoporosis and asthma. These are two-point animal protocols and are noted here for completeness rather than cited as evidence about the point in humans.

What is missing should be said plainly: the human trials that isolate BL-23 are small — sixteen, eight and sixty participants — and measure biomarkers or quality-of-life scores rather than hard clinical outcomes. There is no large randomised trial of BL-23 alone for low back pain, its commonest use.

How does BL-23 compare with the points around it?

Ming Men DU-04 lies directly medial on the midline at the same L2 level and is BL-23's constant partner for warming yang; where BL-23 reaches the Kidney organ, DU-04 addresses the Governing Vessel and the "gate of life" between the Kidneys. Zhi Shi BL-52 is on the outer Bladder line three cun lateral at the same level — the outer companion, associated with the will. San Jiao Shu BL-22 above at L1 and Qi Hai Shu BL-24 below at L3 are its immediate neighbours on the inner line; BL-24, "Sea of Qi Shu", is named for and functions as the back counterpart of Qi Hai REN-06. Da Chang Shu BL-25 at L4 is the Large Intestine Back-Shu point and the more local choice for lower lumbar and sacral pain. Tai Xi KI-03 at the ankle is BL-23's distal partner, the Yuan-Source point of the Kidney channel. Jing Men GB-25 on the flank is the Kidneys' Front-Mu point and BL-23's front-of-body counterpart. And Yao Yan, the extra point further out in the lower back, is the one most often mistaken for BL-23's equivalent — it is a local point of the lumbar region, not a Kidney point.

Source: Deadman & Al-Khafaji, A Manual of Acupuncture (p. 283); Chinese Acupuncture & Moxibustion (p. 180); Sacred Lotus sources & references (BL-23 record; Back-Shu and Front-Mu point sets and the Yao Yan extra-point record queried directly); PMID 37542799; PMID 41312958 (PMC12743158); PMID 35473346; PMID 29231589; PMID 29231345; PMID 40797416 (PMC12338299) — each verified resolvable and checked for retraction status before citation; cross-referenced against multiple online sources.