BL33 Middle Bone-Hole

Reviewed by · Licensed Acupuncturist & TCM Physician · Last reviewed June 2026

BL33 (Zhongliao, “Middle Bone-Hole”) is an acupuncture point on the Bladder Meridian. BL33 is in the 3rd posterior sacral foramen, inferior to BL32. It regulates menstruation, stops leucorrhea, benefits urination, strengthens the back and legs.

Location

BL33 is in the 3rd posterior sacral foramen, inferior to BL32.

Needling

Perpendicular insertion 0.8-1.2 cun.

⚠ Pregnancy: avoid — may stimulate uterine contraction (miscarriage / early-labour risk).

TCM functions

Regulates menstruation, stops leucorrhea, benefits urination, strengthens the back and legs.

Indications

Irregular menstruation, leucorrhea, dysuria, constipation, low back pain.

Clinical notes

Zhongliao, another of the Ba Liao points, shares similar functions with Shangliao but is often considered more potent for urinary and reproductive issues. It is highly effective for regulating menstruation, stopping leucorrhea, and benefiting urination, addressing conditions such as dysmenorrhea, irregular menstruation, and urinary retention. Its deep needling can stimulate the sacral nerves, making it valuable for lower back pain and sciatica radiating down the leg.

On the Bladder channel

BL33 is one of 67 points on the Bladder Meridian. Nearby points:

Frequently asked questions

Where is BL33 located?

BL33 is in the 3rd posterior sacral foramen, inferior to BL32.

What is BL33 used for?

BL33 regulates menstruation, stops leucorrhea, benefits urination, strengthens the back and legs. Common clinical indications include irregular menstruation, leucorrhea, dysuria, constipation, low back pain.

How is BL33 needled?

Perpendicular insertion 0.8-1.2 cun. Caution: ⚠ Pregnancy: avoid — may stimulate uterine contraction (miscarriage / early-labour risk).

Which meridian is BL33 on?

BL33 is a point on the Bladder Meridian (Zú Tài Yáng Páng Guāng Jīng).

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⚠️ This page is for general education and is not medical advice. Acupuncture is a traditional practice; evidence varies by condition and study quality, and individual results differ. It does not replace diagnosis or treatment by a licensed professional. Always consult a qualified acupuncturist or physician.