Da Cheng Qi Tang (大承气汤): Major Order the Qi Decoction — TCM's Classic Purgative
Learn about Da Cheng Qi Tang, the most powerful purgative formula in TCM. Discover how it treats severe constipation with interior excess heat through its dramatic downward-draining action, and why its precise usage protocol is critical.
Da Cheng Qi Tang: When Downward Force Is the Cure
Da Cheng Qi Tang (大承气汤, Dà Chéng Qì Tāng), or Major Order the Qi Decoction, is the most powerful purgative formula in Chinese medicine. It belongs to the downward-draining (下法) category of treatments and is used for the most intense form of interior excess: Yangming Organ Excess (阳明腑实证), where heat and dry stool create a severe blockage in the intestines.
This is not a formula for ordinary constipation. It is an emergency prescription — a controlled therapeutic “storm” that forces stagnant, toxic material downward and out of the body. Its power demands precision: used correctly, it can resolve life-threatening conditions within hours; used incorrectly, it can devastate a patient with weak constitution.
The formula originates from Zhang Zhongjing’s Shang Han Lun (伤寒论), written around 200 CE, and has been a cornerstone of emergency TCM for over 1,800 years.
Ingredients
| Herb | Pinyin | Dose | Role | Function |
|---|---|---|---|---|
| Da Huang | 大黄 | 12g (highest) | King | Purges accumulations, drains heat, moves blood |
| Mang Xiao | 芒硝 | 9g | Minister | Softens hard stools, drains heat through osmotic action |
| Hou Po | 厚朴 | 15g | Assistant | Moves Qi, reduces abdominal fullness and distension |
| Zhi Shi | 枳实 | 12g | Assistant | Breaks up Qi stagnation, forcefully moves the bowels |
Why These Four Herbs Work Together
The formula addresses three aspects of the blockage simultaneously:
- Da Huang pushes — it directly stimulates the intestines to move and expels stagnant material
- Mang Xiao softens — it draws moisture into the dry, hardened stool, making it possible to pass
- Hou Po + Zhi Shi create space — they move Qi and reduce the bloating and distension that make the blockage worse
Without Mang Xiao, Da Huang would push against rock-hard, dry stool with no way to soften it. Without Hou Po and Zhi Shi, the gas and bloating would prevent effective purgation. All four herbs are essential.
Key Indications: The Four Key Signs (痞满燥实)
Da Cheng Qi Tang is indicated when all four of these signs are present:
| Sign | Chinese | Description |
|---|---|---|
| Epigastric fullness | 痞 (Pǐ) | A feeling of fullness and blockage in the upper abdomen, pressure without pain |
| Abdominal distension | 满 (Mǎn) | Visible swelling and bloating of the entire abdomen |
| Dryness | 燥 (Zào) | Extremely dry, hard, sheep-dropping-like stool that cannot pass; dry mouth and tongue |
| Excess solidity | 实 (Shí) | Pain that worsens with pressure, a firm, palpable mass in the abdomen, refusal of food |
Additional Signs
- High fever — intense interior heat
- Profuse sweating — heat forcing fluids out
- Delirium and confusion — heat affecting the Shen (spirit)
- Abdominal pain that worsens with pressure — excess pattern confirmed
- Yellow, dry tongue coating — or even black, thorny coating in severe cases
- Deep, forceful pulse — especially at the right middle position
Classic Decoction Method
The preparation of Da Cheng Qi Tang follows a strict sequence:
- First: Decoct Hou Po and Zhi Shi — these need the longest cooking to extract their Qi-moving oils
- Then: Add Da Huang near the end of cooking — it should only simmer briefly (5–10 minutes) to preserve its purgative anthraquinones
- Finally: Dissolve Mang Xiao into the strained decoction — it is a mineral salt that dissolves rather than decocts
This order matters. Overcooking Da Huang destroys its purgative potency, and failing to dissolve Mang Xiao separately wastes its softening action.
Clinical Response
After taking Da Cheng Qi Tang, the patient should pass stool within a few hours. The traditional instruction is:
- If stool is passed: Stop taking the formula immediately — the mission is accomplished
- If no stool after one dose: A second dose may be given
- Once the blockage clears: Transition to a gentler formula to restore normal function
The goal is always the minimum effective dose — never more than necessary.
Modern Clinical Applications
Contemporary TCM practitioners use Da Cheng Qi Tang or modified versions for:
- Acute intestinal obstruction — non-surgical cases with confirmatory signs
- Severe constipation with fever — post-surgical, post-stroke, or bedridden patients
- Acute pancreatitis — as adjunctive therapy to drain pancreatic secretions
- Appendicitis (early stage) — combined with heat-clearing herbs
- Hepatic encephalopathy — reducing ammonia absorption by clearing intestinal contents
- Post-operative ileus — restoring bowel motility after surgery
Contraindications — Critical
This formula is contraindicated in:
- Deficiency patterns — pale complexion, soft abdomen, weak pulse, chronic fatigue
- Pregnancy — the intense downward-forcing action threatens the fetus
- Elderly or frail patients — unless the excess is truly critical and the constitution can withstand purgation
- Table conditions — when the pathogen is still on the exterior, draining downward drives it deeper
- Stomach cold deficiency — cold, weak digestion with a pale tongue and preference for warm drinks
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FAQ
Who is this article for?
Readers interested in how TCM handles acute, severe conditions — specifically the dramatic 'downward-draining' approach to interior excess heat with constipation.
Can this article replace professional medical advice?
No. This content is educational only and should not replace diagnosis or treatment from a qualified healthcare professional.
Disclaimer
This content is for educational purposes only and does not constitute medical advice. Always consult a qualified healthcare professional for diagnosis and treatment.