What Dachangshu does
Dachangshu is treated here as a practical point rather than a curiosity: where it sits, how it is needled, what the tradition says it does, and the skin conditions in this database that name it.
Actions
- Regulates the Large Intestine
- Removes Qi Stagnation in the Large Intestine
- Strengthens the lower back and legs
Location
One and a half cun measured from the landmark shown in the diagram and the location text, lateral to the lower border of the spinous process of the 4th lumber vertebra (L4).
How to find it
Find the bony landmark first, then feel for the hollow or tender spot the location describes. The point is usually sensitive when pressed. Find Tuffier's line between the highest points of the two iliac crests; the spinous process of L4 usually falls on it. Dachangshu sits 1.5 cun lateral to the lower border of that spinous process, between the medial branch points such as BL-20 and BL-30.
Deqi
De qi at this point is felt as local distension, heaviness or aching, and may travel a short way along the channel.
A cun is a proportional body measurement, not a fixed length: one cun is about the width of the thumb at the knuckle, 1.5 cun about two finger widths, and 3 cun about the width of four fingers. On an average adult one cun is roughly one inch, but it scales with the person, which is why the texts measure in cun rather than centimetres.
Technique
Needling
Angle: 90 degrees, perpendicular Depth: Standard depth one to one and a half cun. Direction: Needle in the direction the location describes.
Moxibustion
Moxibustion is used with the same restrictions as needling at this point.
Skin uses
As the back-shu point of the Large Intestine, Dachangshu is recorded to regulate the Large Intestine and remove Qi stagnation in it, and it lies on the lower back at the fourth lumbar vertebra. The traditional skin reasoning is indirect: where the bowel is sluggish or Qi is stagnant, the paired organ relationship is used to explain a congested, sluggish surface picture, and the point is considered for that stagnation rather than for a named skin disease. The classical indications concern the abdomen and bowels, not the skin. The point has no skin-specific classical indication recorded, so the rationale above stays indirect and is not trial evidence.
No skin-specific classical indication is recorded for this point. The rationale above is an indirect, traditional reading of the point, not a promise of benefit.
Point classifications
| Classification | Value |
|---|---|
| Channel | Meridian |
Safety
Who should treat this point
Acupuncture and moxibustion are practitioner procedures. This page is educational and is not a guide to self-treatment.
Caution
Safety flags: contraindicated or restricted in pregnancy; a nerve runs in the deeper layer; reduce depth in thin or older patients; avoid overstimulation. Needle with care, adjust depth to the patient's build, and modify or avoid the point where a flag applies. The point sits at L4 near the lumbar spinal nerves, so the needle is kept perpendicular and never angled medially toward the spinal canal. In thin patients or with deeper insertion the retroperitoneal space lies anteriorly, and strong stimulation in pregnancy is used cautiously because the point can move Qi downward.
Deficiency and constitution
In a depleted patient the point is worked gently and briefly.
Before treatment
Educational reference only. Skin that is spreading, painful, blistering or accompanied by fever needs medical assessment.
Modern evidence and safety
General references for acupuncture safety and skin evidence. They are not specific to this point, and they are not a claim that needling it treats any condition.
- Acupuncture-related adverse events: systematic review and meta-analyses of prospective clinical studies. BMJ Open, 2021. PMID: 34489268.
- Acupuncture for atopic dermatitis: a systematic review and meta-analysis. BMJ Open, 2024. PMID: 39638592.
- Manual acupuncture for the treatment of chronic spontaneous urticaria: a systematic review and meta-analysis. International Journal of Surgery, 2025. PMID: 40696933.
- Acupuncture in Dermatology: An Update to a Systematic Review. Journal of Alternative and Complementary Medicine, 2021. PMID: 32955916.
Evidence note
No controlled trial of this treatment in skin conditions was identified for this entry. What is described here rests on the classical and later materia medica record and on traditional clinical use, not on controlled trial evidence, and it is not a prediction of benefit. Where skin-specific research does exist it is linked above.
Common questions
What does Dachangshu do in skin practice?
It is used where the skin picture includes the conditions it is used with, always as part of a combination chosen for the pattern.
Is it safe?
Located at L4 level, near the lumbar spinal nerves (L3-L5). Needle perpendicular to appropriate depth; avoid angling medially toward the spinal canal. In thin patients or with deeper needling, there is potential to reach the retroperitoneal space where kidneys and ureters are located anteriorly. Strong stimulation should be used cautiously during pregnancy due to its proximity to the lower abdomen and potential to move qi downward.
Can Dachangshu be used for both diarrhoea and constipation?
Yes. As the Back-Shu point of the Large Intestine it regulates the organ and promotes normal movement, so it is used whether the bowel is too loose or too slow. The choice of partners changes: Pishu BL-20 and Shangjuxu ST-37 for chronic diarrhoea with Spleen weakness, and Qihai REN-6 with Zusanli ST-36 and Zhigou SJ-6 for constipation.
Why is Dachangshu relevant to skin conditions?
Skin eruptions often travel with bowel patterns. When a damp-heat rash sits alongside loose stools, abdominal distension or a greasy tongue coat, treating the Large Intestine through its Back-Shu point helps clear the internal terrain; when dry skin accompanies constipation, the pair addresses the shared fluid deficiency.