Si Mo Tang — Four Milled Herb Decoction

On this page

1. Overview
2. TCM pattern
3. Key herbs
4. Formula actions
5. Conditions treated
6. Cautions

Overview

Si Mo Tang — the “Four Milled Herb Decoction” (so named because the four hard herbs are traditionally ground/milled to extract their essence) — is a Song-dynasty formula from Ji Sheng Fang. It addresses severe Liver Qi stagnation rising upward to invade the chest with shortness of breath, chest tightness, irritability and a sense of suffocation.

The four herbs are Wu Yao, Chen Xiang (or substitute), Bing Lang and Ren Shen. Wu Yao moves Qi warmly; Chen Xiang (aquilaria) descends Qi downward; Bing Lang directs Qi to the lower body; Ren Shen prevents the Qi-moving action from further depleting the patient.

I prescribe Si Mo Tang as part of bespoke herbal formulas from pharmaceutical-grade granules sourced from Sun Ten in Taiwan.

TCM pattern

Si Mo Tang is prescribed for severe Liver Qi stagnation invading the chest:

• Acute chest tightness and oppression from emotional stress
• Shortness of breath — deep breaths impossible
• Sense of suffocation or being unable to breathe out
• Severe irritability or rage
• Possible nausea or vomiting
• Abdominal tension
• Triggered by significant emotional upset
• Tongue — normal to slightly red, thin coat
• Pulse — wiry, possibly tight

Key herbs

1. Chen Xiang (aquilaria) or Wu Yao — warmly moves Qi and descends rebellious Qi (Chen Xiang is from sustainably-harvested cultivated aquilaria)
2. Wu Yao — moves Qi in the lower body
3. Bing Lang (areca seed) — descends Qi downward
4. Ren Shen — tonifies Qi to support the moving action

Formula actions

1. Breaks up severe stagnant Qi
2. Descends rebellious Qi
3. Opens the chest
4. Tonifies Qi to prevent further depletion

Conditions treated

1. Acute panic attack with severe chest tightness
2. Stress-driven shortness of breath
3. Vocal cord dysfunction
4. Acute reactive hyperventilation
5. Severe anxiety with somatic symptoms — see anxiety
6. Acute asthma attack with significant emotional trigger (alongside conventional inhalers)

Cautions

Acute severe chest tightness with breathlessness needs immediate medical assessment to exclude cardiac, pulmonary embolism and other emergencies. Call 999 if accompanied by chest pain, sweating or arm/jaw radiation.

Chen Xiang (Aquilaria) species are CITES-listed; use only sustainably cultivated sources or substitute with synthetic alternatives or other Qi-descending herbs.

Not appropriate for cold or Yin-deficient patterns.

Always consult a qualified Chinese herbalist registered with the RCHM.

Prefer to be treated from home? Chinese herbal medicine online consultations are available throughout the UK and worldwide.