BL23 (Shenshu) — Kidney Shu Point
BL23, known as Shenshu or the Kidney Shu point, is one of the most important points on the Bladder meridian. Located on the lower back, it is traditionally used to support kidney function, relieve low back pain, and restore energy.
At a Glance
| Meridian | Bladder (BL) |
|---|---|
| Body region | Lower back, about two finger-widths beside the second lumbar vertebra (L2) |
| Best for | Low back pain and weakness, fatigue, knee weakness, tinnitus, frequent urination and waking at night |
| Difficulty | Easy to reach with thumbs or palms; easiest lying face down |
| Hold time | 1–2 minutes per side |
| Frequency | 1–2 times daily |
| Pairs well with | CV4 (Guanyuan), BL40 (Weizhong), KI1 (Yongquan) |
| Skip if | Recent back injury or surgery, or unexplained acute back pain — see a doctor first (see Precautions) |
Why BL23 Matters
BL23 is the back-shu point of the Kidney, meaning it is the point on the back where the kidney's qi is said to gather. It sits on the Bladder meridian, which runs in two parallel bands beside the spine. In traditional Chinese medicine the kidneys are regarded as the root of vitality and are classically said to govern the low back and knees, the ears, and reproductive energy. Because of this, BL23 is one of the first points practitioners reach for when a person presents with low back pain, weak knees, fatigue, or low energy.
The point is easy to locate without any equipment because it sits at a consistent landmark — the level of the second lumbar vertebra (L2), which roughly matches the height of the belly button. For someone who spends long hours at a desk or standing, self-massage at BL23 can bring quick local relief to the lower back, and the area responds well to warmth. Along with KI1 and CV4, BL23 is considered a foundational point for supporting energy and resilience in this system, and it is the traditional partner of BL40 for lumbar complaints.
Location
BL23 is on the lower back, on the Bladder meridian, 1.5 cun lateral to the lower border of the spinous process of the second lumbar vertebra (L2) — about two finger-widths out from the spine. To find it, place a hand on your side at the height of your belly button and trace that level horizontally around to your spine; the vertebra at that line is approximately L2. Feel for the small gap between the spinous processes, then move about two finger-widths out from the midline. You should feel a slightly fleshy area between the spine and the long back muscles — that is the point.
Three quick confirmations you have the right spot: (1) the level matches your belly button height (L2); (2) you are in the muscle band beside the spine, not on the spinous process; (3) pressing toward the spine produces a deep, dull, achy warmth rather than a sharp pinch on bone.
When to Use BL23 (and When Not)
Use it when
- • Your lower back feels achy, stiff, or weak after sitting or standing long hours
- • You feel run down, fatigued, or short on energy
- • Your knees feel weak, or you notice ringing in the ears or waking to urinate at night
- • You want a daily point for grounding and stamina
Hold off if
- • You recently injured the lower back or had spinal surgery
- • Back pain came on suddenly with no clear cause — get it checked first
- • Pain runs down the leg, or you have numbness, weakness, or loss of bladder control
- • There is tenderness, a rash, or broken skin over the kidney area
Use the Hold off column as a safety filter: BL23 is a comfort practice for ordinary lower-back tension and fatigue, not a response to an acute back injury or unexplained pain.
Benefits & Uses
- Low back pain: BL23 is a primary point for lower backache, stiffness, and weakness in the lumbar region.
- Kidney and energy support: Traditionally used to support vitality, stamina, and the body's reserves of essential energy.
- Fatigue: Used for general tiredness and low energy, especially when linked to a sense of inner depletion.
- Tinnitus and hearing: Classically linked to the kidneys, which are said to open to the ears, so BL23 is used for ringing in the ears and declining hearing.
- Frequent urination and nocturia: Traditional use for urinary frequency and waking at night to urinate.
- Knee weakness: Included in routines for weak knees, legs, and the traditional "loins" region.
How to Massage BL23
This point is best worked while lying face down, with the pressure directed toward the spine. It responds well to both thumbs working together and to the heel of the palm for a broader, warmer pressure.
- Lie face down on a firm surface with a pillow under your hips to soften the lower back.
- Find L2 by tracing the level of your belly button around to your spine, then move two finger-widths out on both sides.
- Place your thumbs (or the heels of your palms) on both BL23 points.
- Press gently at first, then deepen the pressure and knead toward the spine in slow circles for 1–2 minutes.
- Repeat daily, and finish with a warm compress or heat pack over the area for extra relief.
Common mistake to avoid: pressing directly on the spinous process of the spine itself. The target is the muscle band about two finger-widths out from the vertebra — if you feel hard bone under your thumbs, slide outward and stay on the fleshy muscle.
Combine BL23 with These Points
A full lower-back and energy routine is more effective than pressing one point. Pick the row closest to your situation and work the points in the order shown, 30–60 seconds each.
| Goal / symptom | Routine (in order) |
|---|---|
| Low back pain or stiffness | BL23 → BL40 (Weizhong) → BL23 again, 30–60s each, repeat 1–2 times daily |
| Fatigue or low energy | BL23 → KI1 → CV4 (Guanyuan), holding each 60s, ideally before bed |
| Weak knees or legs | BL23 → KI1 → LI11, then gentle knee bends |
| Tinnitus or waking at night | BL23 → KI1 → HT7, in the evening for a calming close to the day |
For a fuller program, see acupressure for back pain and the back acupressure points body guide.
What to Expect
First session (today)
The point is often tender, and the lower back usually feels looser and warmer within a few minutes. Many people describe a grounding, calming effect rather than an instant energy spike. Do not expect a cure after one press.
Days 3–7 (consistent daily practice)
With 1–2 sessions per day, backache often feels less constant and energy settles into a steadier pattern. This matches the pattern in studies of acupressure for low back pain, where benefits appear after several days of regular use.
Weeks 2–4
For ongoing fatigue or chronic lower-back tension, keep BL23 as one tool alongside movement, sleep, and professional care. Pain that has not improved after 2–3 weeks, pain running down a leg, numbness, or any change in bladder or bowel control is a signal to see a clinician.
Science & Research
Systematic reviews and randomized controlled trials have examined acupressure for pain conditions, including low back pain, with results that are generally promising but limited in quality. Much of the research on back-related acupressure has focused on points along the Bladder meridian, and BL23 is among the most frequently cited for lumbar support in both clinical and self-care settings. Our overview of the acupressure evidence gives a balanced summary of what the research does and does not show.
Overall, current evidence suggests acupressure may help with discomfort and fatigue, but study designs vary widely and many trials are limited by small samples or the difficulty of creating a convincing sham treatment. We therefore describe the effects as supportive rather than guaranteed. Persistent low back pain, urinary symptoms, or numbness in the legs should always be evaluated by a clinician.
Verifiable sources
- Chen YW, Wang HH. The effectiveness of acupressure on relieving pain: a systematic review. Pain Management Nursing. 2014;15(2):539-550. PMID 23415783 · DOI
The review above evaluated acupressure for pain, which is the context where BL23 is most often used. It is not a study of BL23 in isolation.
Precautions
- Press the muscle band beside the vertebra, not the spine itself — never apply direct pressure to bone.
- Avoid strong pressure if you have an acute back injury, fracture, or recent spinal surgery.
- Do not self-treat unexplained, sudden, or severe back pain — get a diagnosis first.
- Skip the point if there is skin irritation, a rash, or tenderness over the kidney area.
- Pregnant women should use gentle, brief pressure on the lower back and consult a care provider first.
Red Flags — See a Professional
Stop self-treatment and see a doctor if you notice any of the following:
- Back pain that came on suddenly with no clear cause, or after a fall or heavy lift
- Pain, numbness, or tingling running down a leg, or weakness in a foot or leg
- Loss of bladder or bowel control, or numbness in the groin area — seek urgent care
- Pain with fever, unexplained weight loss, or a recent illness
- Lower back pain that has not improved after 2–3 weeks of regular practice