Da Cheng Qi Tang
Star大承气汤 (Major Order the Qi Decoction)
Source: Shang Han Lun — Zhang Zhongjing (Han, 220)
Last updated August 30, 2026
Description
Da Cheng Qi Tang (Major Order the Qi Decoction) is the most powerful purgative formula in TCM, clearing Yang Ming organ excess heat through strong purgation. It treats dry stool, severe constipation, and accumulation of heat in the Large Intestine with signs of Yang Ming heat excess. Given its strength, it should be used only when the condition clearly matches and discontinued once the bowels move.
Composition
| Herb | Amount | % | Role | Function |
|---|---|---|---|---|
| Da Huang | 12g | 25% | Jun (Chief) | Purges heat and stagnation, clears Large Intestine. |
| Mang Xiao | 9g | 18.75% | Chen (Deputy) | Softens hardness, moistens dryness, purges heat. |
| Hou Po | 15g | 31.25% | Zuo (Assistant) | Moves Qi, disperses fullness, eliminates distension. |
| Zhi Shi | 12g | 25% | Zuo (Assistant) | Breaks Qi stagnation, reduces accumulation. |
Total weight: 45g
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.
Bitter-cold purging combined with salty softening: together they break up hardened dry stool and drain accumulated heat from the Yang Ming organ far more forcefully than either alone.
Yang Ming fu-organ excess with dry hard stool, abdominal fullness and pain. Contraindicated in pregnancy and in deficiency.
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 (-0.81)
From 100% of the weighed grams.
Grams by band: cold 44%, cool 25%, warm 31%.
Pairs warm and cool. 31% of the weighed grams are warm or hot and 69% cool or cold — the net is their average, not the whole story.
Taste
- pungent 24%
- sour 8%
- bitter 58%
- salty 9%
From 100% of the weighed grams.
Channels reached
- Large intestine 100%
- Stomach 100%
- Spleen 81%
- Lung 31%
- Pericardium 25%
- Liver 25%
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
Decoct Da Huang separately for only 3–5 minutes (over-cooking reduces purgative effect). Add Mang Xiao to the strained decoction just before taking. Take on empty stomach.
Dosage
Decoction: Take warm. Discontinue immediately once stools loosen. Not for use in deficiency patients, post-partum, or during pregnancy.
Conditions Addressed
Related Formulas
Relationships
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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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