Dachangshu (BL25): The Belt-Line Back Point for Low Back Pain and a Stiff Lower Spine

Where Dachangshu Sits

This point sits on the lower back, about two finger-widths out from the centre of the spine, on the belt line: the level where the tops of the two hip bones sit. It lies in the thick muscle beside the spine, low down, where most back pain in later life gathers.

It belongs to the line that Vietnamese and Chinese texts call the Bladder channel. That line starts at the inner corner of the eye, crosses the top of the head, and runs down the back in two tracks on each side of the spine. The inner track, about two finger-widths from the centre, carries a row of points, one for each organ in this tradition. This one, the twenty-fifth stop, belongs to the large intestine.

The old texts place it below the sixteenth vertebra, one and a half units out from the spine. Counting from the top of the back, the sixteenth is the fourth vertebra of the lower back. The World Health Organization standard says the same thing in modern terms: level with the lower border of the fourth lumbar spinous process, one and a half units out from the midline. That fourth bump sits almost exactly on the line between the highest points of the two hip bones, which is why this point is one of the easiest on the back to place. One and a half units is about the width of your index and middle fingers side by side.

Under the skin lies the tough sheet of tissue that wraps the lower back. Below it runs the long muscle that holds the spine upright (the erector spinae), and deeper still, small muscles that steady each vertebra (the multifidus). At this level the long muscles are at their thickest. The skin is served by back branches of the lower lumbar nerves. Close to this level, the fourth and fifth lumbar nerve roots leave the spine to join the large nerve of the leg.

Why This Spot

On the anatomical side, this is where the back takes its heaviest load. The bottom two joints of the lower spine carry the weight of everything above them and do most of the bending. They are where discs wear first and where the small joints thicken with age. The muscles beside them tighten to guard those joints, and the tightness often sits right under this point. If you put your fists into the small of your back after standing at the sink, this is the area you are pushing.

The nerve roots that leave the spine at this level explain why trouble here can send an ache into the buttock and down the leg. Tight muscle alone does not cause sciatic pain, but it often comes along with it, and easing that muscle is something you can do yourself.

In this tradition, each organ has a transport point on the back where its energy is said to rise close to the surface. This is the point of the large intestine, the organ that lets go of what the body no longer needs. That is why the old books list it for bowel complaints as well as for the back. The name says it plainly: da chang is the large intestine; shu means to transport. The Vietnamese name Đại Tràng Du carries the same meaning.

What the Old Texts Say About Dachangshu

The Systematic Classic of Acupuncture and Moxibustion, the Jiayi Jing, compiled by Huangfu Mi in the third century, places this point below the sixteenth vertebra, one and a half units out on each side. The location has stayed the same from that time to the modern standard.

The Vietnamese handbook of points and channels by Ngô Trung Triều, published by Hồng Đức, follows the same count. It tells you to draw a line across the tip of the fourth lumbar bump and meet it with a vertical line one and a half units out from the centre. It lists the point for back pain, twitching and cramping of the back muscles, loose bowels, poor digestion, constipation, weakness of the legs and sciatic pain.

Look at the pattern in that list. Half of it belongs to the back and the leg below it; half belongs to the bowel. Both follow the two ideas behind the point: where it sits, and which organ it is named for.

In the wider tradition, this is the point teachers use for the low, belt-line ache that makes getting out of a chair slow, and for the back pain that comes with constipation or with sitting too long. Its reputation rests on long use rather than proof. It tells you where generations of hands found tender, useful tissue in people with the same aching backs as yours.

Points That Work With Dachangshu

The first partner sits in the middle of the crease at the back of the knee. It is one of the most used points for back pain in this tradition and easy to reach from a chair. Work it after this one when the back is stiff and the legs feel heavy.

The second lies in the side of the buttock. Find the large bony knob at the upper outer thigh and move about a third of the way from it toward the base of the spine. It is paired with this one when pain runs from the low back through the hip and down the side of the leg.

The third lies lower in the buttock, level with the top of the cleft between the buttocks and about four finger-widths out. It is used with this one when the ache sinks deep into the buttock. A tennis ball reaches all three of these back and buttock points.

How to Find and Press Dachangshu

Getting Into Position

Be honest about reach. Pressing the middle of your own lower back with your hands is hard, and harder still with stiff shoulders or sore wrists. Stand with your back to a wall, feet about a foot from it, knees soft, and use a tennis ball between your back and the wall. A stick with a rounded end, reached around the waist, also works. If your shoulders allow it, hands on hips with the thumb tips pressing backward is a third way, though the thumbs tire fast.

How to Find It

Put your hands on your hips with your thumbs pointing back, resting on the top edge of the hip bones. Slide the thumbs back along that edge as far as is comfortable. The line between them crosses the spine at the fourth bump of the lower back. The point lies on each side of the gap below that bump, two finger-widths out from the centre.

Place the ball there and lean back into it slowly. Shift in small steps, a little up, down, in and out. Much of the area will feel like ordinary pressure on thick muscle. One spot will sting: a small, sharp, pinpoint tenderness deep under the ball. That spot is the point. If you feel tingling or a line of pain running down the leg, ease off and move the ball slightly.

How to Press It

Stay on the stinging spot. Bend and straighten your knees a little so the ball rubs in small circles about the size of a coin, roughly one each second, without rolling away. Two balls in a sock let you do both sides at once, with the spine in the gap between them. With a stick, keep the rounded tip on the spot and make the same small circles. Keep off the bony bumps of the spine itself.

How Much Pressure

A sharp sting under the ball is right, and it should fade within moments of stepping away. If the pain stays after you lift off, spreads, or the area turns swollen, hot or red, stop and leave it for several days. Stop at once for tingling, numbness or pain shooting down a leg. If you are holding your breath or clenching your jaw, you are pressing too hard. Step your feet closer to the wall so less weight goes into the ball, until you can breathe slowly through the sting.

How Long

One to three minutes on each side. Keep the first sessions to about a minute, because thick back muscle can feel bruised the next day. Add a little over the following days, up to three minutes. Work both sides, even if only one complains. Once or twice a day is enough. More time brings more soreness, not more benefit.

When to Do It

Morning suits a lower back that is stiff on getting out of bed. Late afternoon suits the belt-line ache that builds after standing, driving or housework. Before bed is a good time too, as part of winding down. Do not press in the middle of the night. If back pain wakes you, getting up to lean on a wall will only wake you more. Keep the pressing for the day and the evening.

What This Won't Do

It will not change a worn disc, a slipped vertebra, thickened joints or a narrowed channel around the nerves. Those are common in the lower back after fifty, and no point reaches them. What this point can do is ease the tight, guarding muscle that comes with them, and give you something useful to do for your back each day. That is a real but modest gain. The things that change a back over months are plainer: walking most days, gentle strengthening for the trunk and hips, breaks from sitting, and a chair and bed that support you. For sluggish bowels, fluids, fibre and movement matter far more than any point.

Some low back pain needs a doctor, not a ball. Go to hospital the same day for numbness between the legs or around the back passage, or new trouble controlling your bladder or bowels. Get seen urgently if a leg or foot turns weak or starts to drag. See a doctor promptly for back pain after a fall, especially if your bones are thin, for pain with fever, for pain that is worse lying still at night, and for pain that worsens week on week. Blood in the stool, or a lasting change in your bowel habit, always needs to be checked.

Safety First

If you are pregnant, skip this one. The low back carries a traditional caution in pregnancy. Do not press over skin that is broken, burned, infected, badly bruised or rashy. Leave the area alone after a recent back injury or fall, with a known fracture in the spine, after recent back surgery, or with unexplained swelling or a lump. If you take blood thinners, bruise easily, have thin bones or reduced feeling in your legs, use a softer ball, lean in less, keep sessions short, and ask your doctor first.

Stop at once if pain stays after you lift off, spreads, or brings tingling or numbness. Nothing here requires you to push through pain. For the full list of cautions and the situations where pressing on yourself is not appropriate, read the full safety guide before you begin.

Questions People Ask

Where is the Dachangshu (BL25) pressure point? Dachangshu (BL25) lies on the lower back, about two finger-widths out from the centre of the spine, on the line that joins the tops of your two hip bones. Put your hands on your hips with thumbs pointing back; the line between your thumbs crosses the spine at the right level. In Vietnamese it is called Đại Tràng Du.

How do I press a point I cannot reach? Let a wall and a tennis ball do it. Stand with your back to a wall, place the ball over the spot and lean in. Two tennis balls tied in a sock sit on both sides of the spine at once. A stick with a rounded end works too. Most people cannot press this area well with their hands, and that is normal.

Is Dachangshu (BL25) good for sciatica? In this tradition it is commonly used for low back pain that runs into the buttock and down the leg. The nerve roots that form the large nerve of the leg leave the spine close to this level. Pressing can ease tight muscle here. It does not change a disc or a narrowed channel pressing on the nerve itself.

Why is a back point named after the bowel? In this tradition every organ has a matching point on the back, and this is the one for the large intestine. The old books list it for sluggish or loose bowels as well as back pain. The name reflects that old map. For bowel changes that are new or lasting, see a doctor.

How long should I press Dachangshu? One to three minutes on each side. Keep the first sessions to about a minute, then add a little as the days go on, up to three. Once or twice a day is enough. Work both sides, even when only one side aches.

Can I press it while pregnant? No. If you are pregnant, skip this one. The low back carries a traditional caution in pregnancy. Ask your midwife or doctor about safe ways to ease back pain.

Other Points in This Library

Each of these sits within reach of the same hand. They are often worked in the same sitting.

This page shares general information about a traditional practice. It is not medical advice and does not replace what your doctor has given you. If you are pregnant, managing a health condition, or unsure whether this applies to you, check with your doctor first.

The whole inner edge of the foot, laid out on one page with photographs, is in The Foot Map — the free book. For every point in this library, see the full pressure point index.

(Point shown: BL25 · Dachangshu · Large Intestine Transport Point · Đại Tràng Du.)