Si Ni San (四逆散) — Frigid Extremities Powder
Si Ni San is the classical Chinese herbal formula from Zhang Zhongjing’s Shang Han Lun for cold hands and feet, hypochondriac pain, IBS[5] and stress-related symptoms — arising not from Yang deficiency but from Liver Qi stagnation preventing the smooth flow of Yang to the extremities. Just four herbs — Chai Hu, Bai Shao, Zhi Shi and Zhi Gan Cao — combine to spread Liver Qi, soften the Liver and regulate the Spleen. It is the structural ancestor of Xiao Yao San, Chai Hu Shu Gan San and many other modern Liver-Qi-regulating prescriptions.
On this page
- Overview
- TCM pattern
- Key herbs
- Formula actions
- Conditions treated
- Cautions
- Frequently asked questions
Overview
Si Ni San — Frigid Extremities Powder — is a deceptively simple but clinically profound formula from Zhang Zhongjing’s Shang Han Lun. Despite its name, it does not treat cold from Yang deficiency but cold extremities arising from Liver Qi stagnation preventing the smooth flow of Qi and Yang to the limbs. It serves as the structural ancestor of many important derivative formulas, including Xiao Yao San and Chai Hu Shu Gan San.
TCM pattern
Prescribed for Liver Qi stagnation with Yang Qi not reaching the extremities, characterised by: cold hands and feet (despite normal body temperature), hypochondriac or abdominal pain, irritability, a wiry pulse, and symptoms that worsen with emotional stress.
Key herbs
- Chai Hu (Bupleurum chinense root, 5-12g) — spreads Liver Qi and releases constraint; raises Yang to reach the extremities
- Bai Shao (Paeonia lactiflora root, 4-24g) — nourishes Blood, softens the Liver and alleviates pain
- Zhi Shi (Citrus aurantium immature fruit, 2-12g) — breaks up Qi stagnation and reduces distension
- Zhi Gan Cao (honey-fried Glycyrrhiza root, 1.5-9g) — harmonises the formula and moderates pain
Formula actions
- Spreads Liver Qi
- Resolves constraint
- Regulates the Spleen
- Alleviates pain
Conditions treated
- Cold hands and feet from Liver Qi stagnation — the patient feels generally warm but the hands and feet are cold
- IBS with abdominal pain, cramping and bloating from Liver invading the Spleen
- Hypochondriac pain and chest tightness from Liver Qi stagnation
- Stress and emotional tension producing physical symptoms
Cautions
Always consult a qualified Chinese herbalist registered with the Register of Chinese Herbal Medicine (RCHM). Online herbal consultations are available. See the prices page for costs.
Prefer to be treated from home? Chinese herbal medicine online consultations are available throughout the UK and worldwide. After a full video consultation, Dr (TCM) Attilio D'Alberto formulates a bespoke herbal prescription and posts your Chinese herbs directly to your door.
Frequently asked questions about Si Ni San
What is Si Ni San used for?
Si Ni San is used for cold hands and feet from Liver Qi stagnation, IBS with abdominal pain and bloating from Liver invading the Spleen, hypochondriac pain, chest tightness, premenstrual breast tenderness, and stress-related physical symptoms that worsen with emotional tension. The defining feature is that the patient is not generally cold — only the extremities are cold while the body feels warm.
How is Si Ni San different from Xiao Yao San?
Si Ni San is the structural ancestor of Xiao Yao San. Both treat Liver Qi stagnation but Si Ni San is leaner and more focused on moving stagnant Qi and resolving cold extremities — useful where Blood deficiency is not prominent. Xiao Yao San adds Blood-nourishing and Spleen-tonifying herbs for the broader picture of Liver Qi stagnation with Blood deficiency and Spleen weakness.
Can Si Ni San be taken for IBS?
Yes — Si Ni San is one of the principal classical formulas for stress-driven IBS, particularly where abdominal pain and cramping are relieved by defecation, symptoms worsen with emotional tension, and there is a strong Liver-invading-Spleen picture. It is often prescribed as a modified version with additional herbs based on the specific IBS subtype (predominant constipation[11], diarrhoea or alternating).
Why are the hands and feet cold if it is not Yang deficiency?
The mechanism is Liver Qi stagnation preventing the smooth circulation of Yang Qi to the limbs — the warmth is present in the body but cannot reach the extremities because Qi flow is constrained. The differential is critical: cold extremities from true Yang deficiency present with cold lower back, frequent night urination, pale complexion and feeling generally cold; cold from Liver Qi stagnation presents only at the extremities with normal core warmth.
Is Si Ni San safe in pregnancy?
Should be prescribed only by a qualified RCHM herbalist with pregnancy training. The formula is generally considered safer than many Liver-moving formulas because the herbs are mild, but its use in pregnancy depends on the specific clinical presentation. Self-prescription is not appropriate at any stage.
References
[5] Liu Q, Shi Z, Zhang T, Jiang T, Luo X, Su X, Yang Y, Wei W. Efficacy and Safety of Chinese Herbal Medicine Xiao Yao San in Functional Gastrointestinal Disorders: A meta-Analysis and Trial Sequential Analysis of Randomized Controlled Trials. Front Pharmacol. 2022 Jan 19;12:821802. https://doi.org/10.3389/fphar.2021.821802. PMID: 35126152.
[11] Lyu Z, Fan Y, Bai Y, Liu T, Zhong LL, Liang HF. Outcome of the efficacy of Chinese herbal medicine for functional constipation: A systematic review and meta-analysis. World J Clin Cases. 2022 May 26;10(15):4856-4877. https://doi.org/10.12998/wjcc.v10.i15.4856. PMID: 35801027.
