Wu Pi San (Wu Pi Yin) — Five-Peel Decoction

On this page

1. Overview
2. TCM pattern
3. Key herbs
4. Formula actions
5. Conditions treated
6. Comparisons with related formulas
7. Modifications
8. Cautions

Overview

Wu Pi San — the “Five-Peel Decoction” (also Wu Pi Yin, “Five-Peel Drink”) — is an elegant classical formula built entirely from the peels (pi) of five botanicals. The principle is the “doctrine of signatures” in TCM: just as the peel surrounds and contains the inner fruit, peel herbs work on the surface and drain the periphery of the body. The formula is therefore ideal for generalised edema — fluid retention through the whole body, particularly under the skin and in the limbs.

The formula appears in multiple classical sources, from Hua Tuo’s Zhong Cang Jing to the Tai Ping Hui Min He Ji Ju Fang. It has remained one of the most-used edema formulas for over a thousand years because it drains fluid without injuring Qi or Yin, making it suitable for patients with edema accompanied by general weakness.

I prescribe Wu Pi San as part of bespoke herbal formulas from pharmaceutical-grade granules sourced from Sun Ten in Taiwan.

TCM pattern

Wu Pi San is prescribed for Spleen failing to transform fluids with skin-level edema (pi shui):

• Generalised body swelling — face, eyelids, limbs, ankles
• Pitting oedema of the lower limbs
• Sensation of heaviness
• Mild shortness of breath on exertion
• Reduced urination
• Abdominal distension
• Fatigue
• Tongue — pale, swollen, possibly with teethmarks; white moist coat
• Pulse — soft, slippery, slow

Key herbs

1. Sang Bai Pi (mulberry root bark) — descends Lung Qi and promotes urination from the upper body
2. Chen Pi (tangerine peel) — regulates Qi and harmonises the Spleen
3. Fu Ling Pi (poria skin) — promotes urination; specifically drains skin-level fluid
4. Sheng Jiang Pi (ginger skin) — gently promotes urination and harmonises
5. Da Fu Pi (areca peel) — descends Qi and drains fluid

Formula actions

1. Promotes urination and reduces edema
2. Regulates Qi in the chest and middle burner
3. Strengthens the Spleen’s transformation of fluids
4. Drains fluid from the skin level

Conditions treated

1. Generalised edema from Spleen dysfunction
2. Pregnancy edema — one of the safer formulas in pregnancy — see pregnancy support
3. Premenstrual fluid retention
4. Heart failure edema (alongside conventional management)
5. Kidney disease with edema (alongside nephrology care)
6. Nephrotic syndrome
7. Liver cirrhosis with ascites (alongside hepatology care)
8. Idiopathic edema
9. Morning facial puffiness — see puffy face and puffy face in the morning
10. Ankle swelling after long sitting/standing
11. Post-corticosteroid water retention

Comparisons with related formulas

• Wu Ling San — for fluid retention with thirst and urinary symptoms; uses different herbs (Fu Ling, Zhu Ling, Ze Xie, Bai Zhu, Gui Zhi).
• Zhen Wu Tang — for severe edema from Kidney Yang deficiency with cold; stronger Yang-warming action.
• Yue Bi Tang — for acute wind-water edema with fever; opposite cold/heat indication.
• Fang Ji Huang Qi Tang — for Qi-deficient edema with sweating and weakness.
• Shi Pi San — for Yang-deficient edema with cold limbs and abdominal pain.

Modifications

• For Spleen Qi deficiency overlay (fatigue, loose stools), add Bai Zhu and Huang Qi
• For Kidney Yang deficiency overlay (cold, lower back ache), combine with Zhen Wu Tang principles
• For Liver Qi stagnation overlay (PMS edema, irritability), combine with Xiao Yao San
• For Damp-Heat overlay (yellow urine, tongue with yellow coat), add Yin Chen and Chi Xiao Dou
• For prominent abdominal distension, add Hou Po and Mu Xiang

Cautions

Edema needs medical assessment to identify the underlying cause — heart, kidney, liver, lymphatic, thyroid and venous problems all need conventional diagnosis. Chinese herbs are an adjunct, not a substitute.

Pregnancy edema is common but can also indicate pre-eclampsia — sudden swelling with headache, visual disturbance or upper-abdominal pain needs urgent medical assessment.

Generally safe in pregnancy but always consult a qualified TCM practitioner trained in pregnancy.

Use cautiously in patients with severe Yang deficiency — the formula does not warm Yang; combine with warming formulas if needed.

Always consult a qualified Chinese herbalist registered with the RCHM.

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