ST-18 (Ru Gen) Breast Root

What does ST-18 Ru Gen do?

Ru Gen ST-18 is the principal point of the classical corpus for the breast — the Stomach channel's own point at the base of the breast, used above all for insufficient lactation, blocked milk and mastitis. The reason a Stomach channel point governs the breast is anatomical in the tradition's own terms: the Stomach channel of Foot Yang Ming descends the front of the chest and passes directly through the nipple, and ST-18 is the point where it leaves the breast and continues onto the abdomen. Sacred Lotus sources & references record two actions for it, and both follow from that position.

• Benefits the breasts and reduces swelling — the defining action. This is the recorded basis for its use in insufficient lactation, in milk that will not flow, in breast distension and in mastitis and breast abscess. Where REN-17 Shan Zhong on the midline opens the chest as a whole, ST-18 acts on the breast itself from beneath it.
• Unbinds the chest and alleviates cough and wheezing — the second recorded action, and the one readers most often overlook. Sitting in an intercostal space on the chest wall, ST-18 is documented for chest pain, for a tight oppressed chest, and for cough and wheezing. Our own indication record carries cough and asthma alongside the breast indications.
• Regulates qi in the chest and hypochondrium — an extension of the same action rather than a separate one: the reference literature records ST-18 for fullness and distension of the chest and for pain running between the ribs, which the tradition reads as qi failing to move freely in this region.

Two things are worth stating plainly about this point's classification. First, ST-18 carries no five-shu, yuan, luo, xi-cleft, back-shu or front-mu category in our records and none in the standard references — it is an ordinary channel point whose whole importance comes from where it sits. Second, that is not a weakness: a point does not need a category to be indispensable, and ST-18's position at the root of the breast makes it the one point that almost every acupuncture prescription for the breast in the published literature contains.

Source: Sacred Lotus sources & references (channel and existing action record); Deadman & Al-Khafaji, A Manual of Acupuncture (p. 143); Chinese Acupuncture & Moxibustion (pp. 149–150); cross-referenced against multiple online sources.

What is ST-18 Ru Gen used for?

Ru Gen ST-18 is used above all for disorders of the breast — insufficient lactation, blocked or difficult milk flow, breast distension and mastitis — and secondarily for cough, wheezing and pain in the chest. 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 safety facts set out under needling.

• Insufficient lactation — too little milk after childbirth
• Milk that will not flow, and blocked or difficult let-down
• Mastitis and breast abscess
• Breast distension, swelling and pain
• Lumps, nodules and hyperplasia of the breast
• Pain in the chest
• Fullness and oppression of the chest
• Cough
• Wheezing and difficult breathing
• Pain in the hypochondrium and between the ribs
• Hiccup and belching attributed to rebellious qi in the chest
• Pain that stops the sufferer turning or lying on that side

Source: Sacred Lotus sources & references (existing indication record); Deadman & Al-Khafaji, A Manual of Acupuncture (p. 143); Chinese Acupuncture & Moxibustion (pp. 149–150).

Where is ST-18 Ru Gen, and how is it used in practice?

Ru Gen lies on the front of the chest directly below the nipple, at the lower edge of the breast, in the fifth space between the ribs — four cun out from the midline of the body. The name is a plain description of that position: it is the point at the root of the breast. It is the eighteenth point of the Stomach channel, one below Ru Zhong ST-17 at the nipple itself, and it is the last of the channel's chest points before the channel crosses onto the abdomen.

Which points is ST-18 combined with?

• For insufficient lactation — the standing classical combination is ST-18 with Shan Zhong REN-17 between the breasts and Shao Ze SI-01 at the corner of the little fingernail, with Zu San Li ST-36 added to build qi and blood and Tai Chong LIV-03 where the milk is held back by constrained qi. This is not only the textbook combination but demonstrably the one in actual use: an analysis of 102 published clinical studies of acupuncture and moxibustion for postpartum insufficient lactation extracted 108 prescriptions using 65 points across 654 uses, and found the three most-used points to be Danzhong CV-17, Rugen ST-18 and Shaoze SI-01, with the Stomach channel the most frequently involved channel of all (Zhongguo Zhen Jiu 2020;40(8):897–901, PMID 32869603). A separate analysis of 120 clinical studies identified the five-point group CV-17, ST-18, ST-36, SI-01 and LR-03 as the highest-frequency combination in the literature (Zhongguo Zhen Jiu 2020;40(10):1138–42, PMID 33068361).
• For mastitis and breast abscess — with Jian Jing GB-21 at the crest of the shoulder, the other great classical breast point, and Zu Lin Qi GB-41 as the distal Gall Bladder point; Qi Men LIV-14 and Tai Chong LIV-03 are added where the pattern is one of constrained Liver qi.
• For breast lumps and hyperplasia — the published prescription literature is unusually clear here too. A complex-network analysis of 312 articles on acupuncture and moxibustion for hyperplasia of the mammary glands extracted 343 prescriptions using 113 points across 1,998 uses, and identified as core points CV-17, LR-14, SP-06, LR-03, ST-36, GB-21, Rugen ST-18, ST-15, P-06, ashi points, ST-40, CV-04, KI-03, SI-11, BL-18 and LI-04 (Zhen Ci Yan Jiu 2021;46(1):76–83, PMID 33559431). Every named point in that list is held in this library; "ashi points" are tender spots found by palpation rather than a fixed location, and so have no page of their own.
• For cough, wheezing and chest oppression — with Shan Zhong REN-17, Fei Shu BL-13 as the Back-Shu point of the Lungs, and Lie Que LU-07 distally.
• Method — Sacred Lotus sources & references record moxibustion as applicable at this point, and moxa or acupressure at ST-18 is a common alternative to needling precisely because of the anatomy set out under needling.

How does ST-18 relate to the other breast points?

The Stomach channel gives a vertical column of four points down the front of the chest, all held here: Wu Yi ST-15 in the second intercostal space, Ying Chuang ST-16 ("Breast Window") in the third, Ru Zhong ST-17 ("Breast Centre") at the nipple in the fourth, and Ru Gen ST-18 ("Breast Root") in the fifth. Read in sequence, the names trace the breast from above it, to its window, to its centre, to its root. ST-17 is the important exception among them: Sacred Lotus sources & references record that it serves only as a landmark for locating points on the chest and abdomen — it is not needled and not moxaed, and it exists in the point list to fix the vertical line that the other points are measured from. ST-18 is therefore the working point of the group, and it is the one the prescription literature actually uses.

Source: Sacred Lotus sources & references (location, channel, neighbouring Stomach-channel chest points and their records, all queried); Deadman & Al-Khafaji, A Manual of Acupuncture (p. 143); Chinese Acupuncture & Moxibustion (pp. 149–150); PMID 32869603; PMID 33068361; PMID 33559431; cross-referenced against multiple online sources.

Where is ST-18 located?

• A Manual of Acupuncture (p. 143): Directly below the nipple, in the fifth intercostal space.
• Chinese Acupuncture and Moxibustion (p. 149-150): On the chest, directly below the nipple, on the lower border of breast, in the 5th intercostal space, 4 cun lateral to the anterior midline.

How is ST-18 Ru Gen needled, and why is it a high-risk point?

One anatomical fact has to be stated before anything else. ST-18 lies in an intercostal space on the front of the chest wall — the pleura and the lung lie directly beneath it — and pneumothorax, a punctured lung, is the documented complication of needling points in this band. This is why every reference text records an oblique or transverse angle along the intercostal space at this point, and never a perpendicular one, and why the recorded depth is among the smallest given for any point on the body. An oblique needle travels along the chest wall between the ribs; a perpendicular one travels toward what lies behind it. That distinction is the substance of the safety record, not a stylistic detail. Everything below is neutral reference data describing what the textbooks and the published anatomical 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 oblique insertion of 0.3 to 0.5 inch at ST-18, with moxibustion applicable. The angle recorded is oblique, not perpendicular.
• Chinese Acupuncture & Moxibustion (pp. 149–150) and Deadman & Al-Khafaji (p. 143) both record oblique or transverse insertion at this point, directed along the line of the intercostal space, and both attach an explicit caution against deep or perpendicular insertion because of the lung beneath.
• For comparison within our own records: 0.3–0.5 inch at ST-18 is the same shallow figure held here for Jian Jing GB-21 over the apex of the lung and for Qi Men LIV-14 one intercostal space lower, and roughly one-third of the 0.8–1.0 inch recorded for Liang Men ST-21 further down the same channel on the abdomen. Depth figures in this literature track the structure underneath, not the size of the region.
• Moxibustion is recorded as applicable, and is one reason ST-18 is frequently treated without needling at all.

The measured anatomy — and exactly which point each study measured

This is where precision matters most, because measurements made at one chest point are routinely and wrongly read across to another. What follows names the point each study actually measured.

• ST-18 itself has been measured, in children. A retrospective study of chest computed-tomography images from 319 patients aged 4 to 18 (205 boys, 114 girls) measured the depth from skin to the major organs at chest acupoints and defined that distance as the point's safe depth. ST-18 was one of the points measured by name. The mean depth at ST-18 was 13.35 ± 4.82 mm in boys and 14.96 ± 7.33 mm in girls (P = 0.04), and it rose steadily with age — from 10.55 ± 3.66 mm in the 4-to-6 group to 16.31 ± 6.87 mm in the 16-to-18 group. Depth also differed significantly by weight and body-mass index. In other words, at ST-18 in a young child the lung may lie little more than a centimetre beneath the skin (Ma YC et al., Evid Based Complement Alternat Med 2015;2015:126028, PMID 26457105, PMC4592721).
• Adult chest points have been measured by computed tomography, but ST-18 is not confirmed by name in that report. A study of 120 adults divided by body weight, height and sex measured, for commonly used chest points, the distance from the skin surface to the thoracic pleura and defined it as the safe depth; the paper names the Conception Vessel, Kidney, Stomach, Pericardium, Lung, Spleen and Gall Bladder channels as the sources of the points measured, and found significant differences between body-size groups. Its stated premise is the relevant one: for points on the human chest, insertion beyond the safe level can cause pneumothorax, internal bleeding or other organ damage (Sheu CY, Lin JG, Zhonghua Yi Xue Za Zhi (Taipei) 1992;50(5):388–99, PMID 1338010). It is cited here for the principle it establishes about the chest as a whole; no individual figure from it is attributed to ST-18.
• The much-quoted ultrasound depths of 17.4 mm in men and 14.6 mm in women are not ST-18 figures. Those were measured at Jian Jing GB-21 on the shoulder, in 101 adults, and they belong to that point (J Acupunct Meridian Stud 2018;11(6):355–360, PMID 29936338). They are mentioned here only to prevent the confusion, which is common.
• No single agreed safe depth exists for any point. Two systematic reviews of the safe-depth literature — 33 studies in the first, 47 in the second, measured by magnetic resonance imaging, computed tomography, ultrasound and cadaveric dissection — both concluded that depths measured for the same point differ greatly between subject groups and measuring methods, and that the definition of "safe depth" has never been standardised (J Altern Complement Med 2011;17(3):199–206, PMID 21417806; Evid Based Complement Alternat Med 2013;2013:740508, PMID 23935678).

What is actually documented, and how often

Pneumothorax. A punctured lung is among the most frequently reported serious adverse events in acupuncture. A systematic review of the Chinese case-report literature from 1956 to 2010 identified 1,038 adverse-event cases across 167 articles, of which 307 were pneumothorax — behind only fainting — with 35 deaths across the whole series, and attributed the events chiefly to improper technique (He W et al., J Altern Complement Med 2012;18(10):892–901, PMID 22967282). An earlier systematic review of the same literature covering 1980 to 2009 found 479 adverse-event cases in 115 articles with 14 deaths, and likewise named pneumothorax as the single most frequent adverse event, concluding that most were owing to improper technique (Zhang J et al., Bull World Health Organ 2010;88(12):915–921C, PMID 21124716, PMC2995190). Fatal cases exist: an autopsy report describes bilateral pneumothoraces following electroacupuncture, with the authors noting that electrical pulses and the muscle contraction they cause may draw needles deeper than the depth at which they were inserted (J Forensic Sci 2022;67(1):377–383, PMID 34435369).

Delayed presentation. The reference literature notes that a pneumothorax following needling over the thorax may not declare itself immediately, presenting hours later with sudden chest pain, breathlessness or a persistent dry cough. It is a medical emergency requiring immediate assessment.

Risk in proportion. A meta-analysis of prospective clinical studies estimated serious adverse events at approximately 1 per 10,000 patients and about 8 per million treatments, concluding that acupuncture is among the safer treatments in medicine (Bäumler P et al., BMJ Open 2021;11:e045961, PMID 34489268). The absolute risk is small and it is concentrated in a small number of anatomically exposed points. The points of the chest wall — ST-18 among them — are where it concentrates.

Source: Sacred Lotus sources & references (existing needling record); Deadman & Al-Khafaji, A Manual of Acupuncture (p. 143); Chinese Acupuncture & Moxibustion (pp. 149–150); PMID 26457105 (PMC4592721); PMID 1338010; PMID 29936338; PMID 21417806; PMID 23935678; PMID 22967282; PMID 21124716 (PMC2995190); PMID 34435369; PMID 34489268 — each verified resolvable and checked for retraction status before citation.

What does the name Ru Gen mean?

Ru Gen means "Breast Root" — ru, the breast, and gen, a root or base. It is one of the plainest names in the point repertoire and needs no commentary to decode: the point lies at the lower border of the breast, where the breast meets the chest wall, and that is exactly what "root" describes. The image also carries the classical sense of a root as the place from which something is nourished — the point being where the tradition holds the breast draws its supply, and the reason ST-18 is the first choice when milk will not come. Its neighbour one space above, Ru Zhong ST-17, is "Breast Centre" at the nipple; taken together the two names map the breast from its middle to its base.

Why does an ordinary point with no category matter this much?

Sacred Lotus sources & references carry no five-shu, yuan, luo, xi-cleft, back-shu, front-mu, confluent or element classification for ST-18, and neither do the standard references. It is worth saying so directly rather than leaving a reader to assume a category was omitted. ST-18's importance is purely positional: it is the Stomach channel's point at the root of the breast, and the Stomach channel of Foot Yang Ming is the channel that traverses the breast, descending the chest through the nipple before crossing onto the abdomen. That single anatomical fact is why a Stomach point governs lactation and mastitis, and it is also why the great shoulder point Jian Jing GB-21 — a meeting point of the Gall Bladder, Sanjiao and Stomach channels, and recorded in our own location data as sitting directly above the nipple — shares ST-18's breast indications. The two are the classical pair for the breast, one above it and one below it.

Is there research on ST-18 Ru Gen?

The honest answer is that no randomised controlled trial isolates ST-18, and none is claimed here. What does exist falls into three groups, all of them genuinely point-specific in the sense that ST-18 is named and analysed rather than buried in a protocol.

• Prescription analysis — how the point is actually used. The two lactation analyses described under practice are the most useful evidence about this point that exists. One extracted 108 prescriptions from 102 published studies of acupuncture and moxibustion for puerperal insufficient lactation and found ST-18 to be the second most-used point of 65, after REN-17 (PMID 32869603); the other analysed 120 studies and found the five-point group containing ST-18 to be the commonest combination in the field (PMID 33068361). A third, on hyperplasia of the mammary glands, extracted 343 prescriptions from 312 articles and placed ST-18 among the 16 core points by complex-network analysis (PMID 33559431). These do not test whether the point works; they establish, quantitatively, that the classical combination and the modern clinical one are the same combination — which is a real and checkable finding.
• Point-property measurement at ST-18. An infrared thermal-imaging study compared surface radiation temperature at named points in patients with hyperplasia of the mammary glands against healthy controls. In controls, left and right readings at the same point were symmetrical. In the patient group, temperatures were higher at almost every point tested, and the increase reached statistical significance at the right Rugen ST-18, Guanyuan CV-04, Qihai CV-06 and Hegu LI-04 (P = 0.046 to P < 0.001), with a left-right imbalance appearing at ST-36, KI-21 and LI-04 (Zheng J et al., Evid Based Complement Alternat Med 2013;2013:567987, PMID 24327822, PMC3847962). It is a small observational study and it shows association rather than mechanism, but it measured ST-18 by name and found a difference there specifically.
• Trial evidence for the combination ST-18 belongs to, not for ST-18 alone. The best trial in this territory is a single-blind randomised multicentre study across three Beijing hospitals which allocated 276 women with postpartum insufficient lactation to acupuncture at Tanzhong CV-17 alone or to a traditional herbal decoction, measuring breast engorgement, milk volume, prolactin, neonatal weight, feeding and crying; both groups improved significantly with no significant difference between them (Zhongguo Zhen Jiu 2008;28(5):317–20, PMID 18652318). That trial tested REN-17, not ST-18, and it is recorded on our REN-17 page for that reason — but it is the largest single-point trial in the lactation literature and ST-18's closest relative in it. Broader syntheses of traditional Chinese medicine interventions for postpartum lactation (Heliyon 2024;10(6):e27154, PMID 38524574) and of acupressure for lactation (MCN Am J Matern Child Nurs 2022;47(6):345–352, PMID 36227074) reach cautiously supportive conclusions about the field as a whole, not about this point.

What is missing should be said plainly: for the point that the prescription literature shows is used in most acupuncture treatments of the breast, there is no controlled trial isolating it. The trials that exist use multi-point protocols; their results belong to the protocol, not to ST-18, and they are not presented here as evidence for it.

How does ST-18 compare with the points around it?

Ru Zhong ST-17 lies one intercostal space above at the nipple itself and is the one point in the region that is never treated — Sacred Lotus sources & references record it as serving only as a landmark for locating other points on the chest and abdomen. Ying Chuang ST-16 and Wu Yi ST-15 continue the same vertical line upward in the third and second intercostal spaces and share ST-18's chest-wall considerations; ST-15 appears alongside ST-18 in the core-point list for breast hyperplasia. Shan Zhong REN-17 sits on the midline between the breasts at the fourth intercostal level and is the Hui-Meeting point of qi — the partner point for every breast indication ST-18 carries. Qi Men LIV-14 lies one space lower, in the sixth intercostal space on the same vertical line, and is the Front-Mu point of the Liver, chosen where the presentation is one of constrained qi rather than of the breast as such. Jian Jing GB-21 at the crest of the shoulder is ST-18's counterpart above the breast. And distally, Shao Ze SI-01 at the little fingernail is the point most consistently named for milk production, and the one ST-18 is most often paired with.

Source: Deadman & Al-Khafaji, A Manual of Acupuncture (p. 143); Chinese Acupuncture & Moxibustion (pp. 149–150); Sacred Lotus sources & references (name, absence of point categories, and neighbouring point records queried in full); PMID 32869603; PMID 33068361; PMID 33559431; PMID 24327822 (PMC3847962); PMID 18652318; PMID 38524574; PMID 36227074 — each verified resolvable and checked for retraction status before citation; cross-referenced against multiple online sources.