Si Ni San
Star四逆散 (Frigid Extremities Powder)
Source: Shang Han Lun (c. 220)
Last updated October 1, 2026
Description
Si Ni San (Frigid Extremities Powder), from the Shang Han Lun, is used to free constrained Liver-Qi; regulate the Spleen.
Presentation: fullness in the chest; distension of hypochondria and abdomen; cold fingers; abdominal pain when Liver overacts on Spleen; stress-related Qi stagnation; pulse: wiry.
Syndrome: Syndrome of Liver-Qi stagnation.
Composition strategy:
- Chai Hu chosen over Xiang Fu because its upward/outward movement suits Qi constraint
- ascending and descending herbs combined to activate Qi movement
- Liver-softening herbs help the Qi spread
- Liver and Spleen harmonized together
Note: the book prints different doses in its two discussions of this formula: Chai Hu 6 g (p. 255) vs 6–9 g (p. 366); Zhi Shi 6 g (p. 255) vs 9–12 g (p. 366); Bai Shao Yao 9 g (p. 255) vs 12–24 g (p. 366); Zhi Gan Cao 6 g (p. 255) vs 6–9 g (p. 366).
Source: Yang Y. Chinese Herbal Formulas: Treatment Principles and Composition Strategies. Churchill Livingstone Elsevier, 2010, p. 255, 366.
Composition
| Herb | Amount | % | Role | Function |
|---|---|---|---|---|
|
Chai Hu
as printed: Chai Hu (Bupleuri radix)
|
6g | 22.22% | Jun (Chief) | disperse Qi and release constraint in Liver, Gall Bladder and San Jiao |
|
Bai Shao
as printed: Bai Shao Yao (Paeoniae radix lactiflora)
|
9g | 33.33% | Chen (Deputy) | with Zhi Gan Cao generate Yin, soften Liver, ease cramp |
|
Gan Cao
also envoy; as printed: Zhi Gan Cao (Glycyrrhizae radix preparata)
|
6g | 22.22% | Chen (Deputy) | strengthen Spleen, protect Middle-Jiao; harmonize |
|
Zhi Shi
as printed: Zhi Shi (Aurantii fructus immaturus)
|
6g | 22.22% | Zuo (Assistant) | descend Qi; regulate intestinal Qi, reduce distension and pain |
Dui Yao — Core Herb Pairs
The classical two-herb combinations at the heart of this formula, as recorded on the herbs' own pages — each pair has an action neither herb has alone.
Energetics dose-weighted
The formula's overall nature, taste balance and channel reach, weighted by each herb's dose. Classical formulas often pair warm and cool herbs on purpose, so a net figure summarises the mix — it doesn't describe every herb in it.
Nature
Net cool (-0.78)
From 100% of the weighed grams.
Grams by band: cool 78%, neutral 22%.
Taste
- pungent 19%
- sweet 22%
- sour 24%
- bitter 35%
From 100% of the weighed grams.
Channels reached
- Spleen 78%
- Liver 56%
- Stomach 44%
- Lung 22%
- Large intestine 22%
- Heart 22%
Share of the grams entering each channel, from 100% of the weighed grams.
Dose-weighted from each herb's recorded nature, taste and channels (missing values are left out, never counted as neutral). It describes the composition — it is not a recommendation.
Preparation
Source text: grind equal amounts to powder, take 6-9g three times daily. Now usually decocted at the listed doses.
Source: Scheid V, Bensky D, Ellis A, Barolet R. Chinese Herbal Medicine: Formulas & Strategies, 2nd ed. Eastland Press, 2009, p. 116.
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Formula family
Each entry reads as the larger formula written out: “+” adds its other catalogue cores, then the herbs none of them hold. A catalogue formula counts as a core only when at least 80% of its herbs are present, no more than 1 is absent, and the absent herb is not its chief.
Formula Network
Formulas that share herbs with this one — the closer to the centre, the stronger the match. Click a node to explore.
Similar Formulas by composition
Match score combines dosage-weighted composition (cosine, 70%) with shared-herb overlap (Jaccard, 30%).
Traditional formula information is for educational purposes only. Herbal formulas should be prescribed by a qualified practitioner — dosages and combinations are individualized and can interact with medications.
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