Gua Lou (Trichosanthes Fruit, also written Gua Lou or Kua Lou; the dried ripe fruit of Trichosanthes kirilowii or T. rosthornii) is the most pharmacologically versatile herb in the TCM Phlegm-Heat clearing category. Its defining character: the entire fruit, the skin (Gua Lou Pi), and the seeds (Gua Lou Ren) are all separately pharmacopoeial-grade drugs with clearly distinct functional emphasis, which is exceptional even among multi-part herbs. TCM character: sweet, mildly bitter, cold; enters Lung, Stomach, and Large Intestine channels. The three-channel entry maps directly to three distinct clinical domains: Lung (clear Heat-Phlegm), chest-Stomach (relieve chest obstruction and scatter binding), Large Intestine (moisten Dryness and promote defecation). The Ben Cao Gang Mu comprehensive summary: “moistens Lung-Dryness, drains Fire, treats cough, washes away Phlegm-binding, benefits the throat, stops wasting-thirst, promotes defecation, dissolves carbuncle-sore toxins.” Zhang Zhongjing’s Jin Gui Yao Lue was the first to deploy Gua Lou clinically in the famous Gua Lou Xie Bai Ban Xia Tang for chest bi-obstruction, establishing its chest-opening action that remains in use nearly two millennia later.
I. Classical Records and Historical Significance
- Shen Nong Ben Cao Jing (middle-class, under Gua Lou / Gua Lou Gen): governs wasting-thirst, body Heat, vexation-fullness, severe Heat, supplements deficiency and settles the Middle — establishing the foundational clear-Heat, moisten-Dryness, relieve-thirst drug value
- Jin Gui Yao Lue (Zhang Zhongjing, Han dynasty): first clinical deployment of Gua Lou in Gua Lou Xie Bai Ban Xia Tang and related formulas; specifically for chest bi-obstruction with Phlegm-turbidity blocking the chest-Yang — establishing the chest-opening-and-Phlegm-scattering application that has been in continuous use since the Han dynasty
- Ben Cao Gang Mu: “moistens Lung-Dryness, drains Fire, treats cough, washes away Phlegm-binding, benefits the throat, stops wasting-thirst, promotes defecation, dissolves carbuncle-sore toxins” — the most comprehensive classical summary of Gua Lou’s five domains
- Chinese Pharmacopoeia: clear Heat and wash away Phlegm, broaden the chest and scatter binding, moisten Dryness and lubricate the intestines
II. TCM Properties, Three Parts and Identification
TCM properties: Sweet, mildly bitter, cold; enters Lung, Stomach, and Large Intestine channels. Drug character: clears and moistens, descends, does not violently attack. Cold clears Heat; bitter resolves Phlegm; sweet moistens Dryness. The three-channel entry provides Gua Lou with a top-to-bottom distribution of action: Lung (upper Jiao — clear Phlegm-Heat and stop cough), chest-Stomach (Middle Jiao — broaden the chest and scatter binding), Large Intestine (lower Jiao — moisten and promote defecation).
Regional origin and quality: Source: Trichosanthes kirilowii or T. rosthornii dried ripe fruit; primary production: Shandong, Henan, Hebei, Anhui; dao di: Shandong Feicheng Gua Lou and Henan Huai Gua Lou (large fruit, well-filled seeds, high oil content). Quality standard: large, complete, orange-red, thick flesh, no mould or insect damage.
The three pharmacopoeial parts — with distinct functional emphasis:
| Part | Character | Primary action | Best for | Cannot do |
|---|---|---|---|---|
| Gua Lou Pi (skin/pericarp) | Light, ascends to the surface | Clear Lung-Heat and resolve Phlegm; broaden the chest and regulate Qi | Lung-Heat cough with copious yellow Phlegm; chest stuffiness and chest pain; Phlegm-Qi stagnation in the chest | Moisten intestines and promote defecation |
| Gua Lou Ren (seeds) | Moist, descends | Moisten Lung-Dryness and resolve Phlegm; lubricate intestines and promote defecation | Lung-Dryness dry cough with little sticky Phlegm; intestinal-Dryness constipation (oil-rich — gentle laxative) | Chest-broadening and Qi-regulating as powerfully |
| Quan Gua Lou (whole fruit) | Comprehensive — both Pi and Ren actions | Clear Heat-Phlegm + broaden chest + scatter binding + moisten Dryness + promote defecation | Most clinically versatile; appropriate when multiple actions are needed simultaneously; the standard form in most classical formulas | N/A — the most comprehensive form |
| Mi Zhi Gua Lou (honey-fried) | Warmth added; moistening enhanced | Moisten Dryness and stop cough more strongly; moderates the Cold nature | Chronic Lung-Dryness cough with constitutional Yin depletion; patients who cannot tolerate the raw cold nature | Strong Heat-clearing action (moderated) |
Core chemical constituents: Trichosanthes saponins; flavonoids; alkaloids; plant oils and fatty acids (the primary intestine-moistening laxative component); polysaccharides; amino acids. Saponins and flavonoids are the primary cardioprotective, expectorant, and anti-inflammatory components.
III. Five Core Actions
1. Clear Heat and wash away Phlegm — clear Lung and stop cough:
The primary Lung-channel action. Gua Lou’s cold nature clears Lung-Heat; its bitter quality resolves and washes away thick sticky Phlegm. Specifically targets: Heat-Phlegm and Dry-Phlegm cough — yellow thick sticky phlegm difficult to expectorate, throat dryness and itch, chest-diaphragm Heat-stuffiness, Lung-Heat dyspnoea. Clinical designation: “first-choice herb for Heat-Phlegm and Dry-Phlegm cough.” The pharmacological sequence: cold-clearing reduces Lung-Heat inflammation; bitter-resolving loosens the Phlegm-matrix; moist-flushing washes away the dissolved Phlegm. Modern pharmacology: inhibits airway inflammation, thins mucus (reducing viscosity), relaxes bronchial smooth muscle — directly supporting the expectorant and antitussive actions.
2. Broaden the chest and scatter binding — unblock chest-bi obstruction and settle pain:
Gua Lou’s most historically important action — the basis for Zhang Zhongjing’s Han dynasty formula design. Opens the chest-diaphragm Qi mechanism; dissolves Phlegm-turbidity and Qi-stagnation obstructing the chest-Yang; specifically treats: chest bi-obstruction producing chest stuffiness and oppression, shortness of breath, chest stabbing pain, chest-rib fullness and distension from Phlegm-turbidity blocking the chest-Yang. Modern pharmacology: dilates coronary arteries; improves myocardial blood supply; reduces vascular resistance; inhibits platelet aggregation — the molecular basis for the chest-opening action in cardiovascular disease.
3. Moisten Dryness and lubricate the intestines — promote defecation gently:
Gua Lou Ren’s oil-rich seeds lubricate the intestinal wall and promote peristalsis. This is the gentle oil-lubricating (run zao hua chang) laxative mechanism — distinct from bitter-cold purgation (Da Huang) or osmotic purging (Mang Xiao). Target pattern: intestinal-Dryness constipation from Lung-Stomach Dryness-Heat and fluid-Yin depletion producing dry-bound stool, difficult defecation, and straining without urgency. The simultaneous upper-lower action is unique: Gua Lou can clear Lung-Heat (addressing the root) while moistening intestines (addressing the manifestation) in the same prescription, because the same Dryness-Heat mechanism produces both the dry cough and the dry stool.
4. Reduce swelling and scatter binding — resolve carbuncle-sore toxins:
Clears Heat and disperses Stasis; dissolves Phlegm-Heat-toxin binding producing nodular accumulations. Addresses: breast carbuncle (ru yong) at initial onset with red swelling pain; Lung carbuncle (fei yong) with coughing purulent sputum; intestinal carbuncle (chang yong) abdominal pain; skin Hot-toxic sores and swellings; breast nodular masses. Modern pharmacology: anti-inflammatory and antibacterial actions; resolves inflammatory exudate — supports the sore-toxin dissolution action.
5. Generate fluids and relieve thirst, clear Heat and relieve vexation:
Clears Stomach-Heat and nourishes Stomach-fluid; improves: Dryness-Heat injuring fluids producing dry mouth and thirst, internal Heat wasting-thirst, copious drinking, vexing fullness from Lung-Stomach Heat exuberance. The Shen Nong Ben Cao Jing’s first-recorded action directly references this — “governing wasting-thirst, body Heat, vexation-fullness.”
IV. Clinical Applications
- Lung-Heat Phlegm-Heat cough: Wind-Heat and Lung-Heat cough with yellow thick sticky phlegm difficult to expectorate, throat-dryness and swelling-pain, dry mouth and Lung-Heat; for acute and chronic bronchitis, Lung-Heat Phlegm-copious respiratory conditions
- Chest bi-obstruction heart pain, chest stuffiness and fullness: Phlegm-turbidity obstructing the chest-Yang producing chest stuffiness and oppression, stabbing chest pain, shortness of breath, chest-diaphragm distension and fullness; adjunctive in coronary artery disease, chest stuffiness and shortness of breath, and chest-rib Qi-stagnation binding
- Lung-Dryness fluid-depletion, intestinal-Dryness constipation: autumn-winter dry-pathogen and internal Heat fluid-depletion producing dry cough with little phlegm, skin dryness, dry-bound stool, habitual intestinal-Dryness constipation; gentle fluid-generating and constipation-relieving without damaging constitutional Qi
- Various carbuncle-sore toxins: initial-onset breast carbuncle with red swelling pain; Lung carbuncle coughing purulent sputum; intestinal carbuncle abdominal pain; skin Hot-toxic sore swellings; clears Heat, scatters binding, dissolves swelling, and settles pain to promote resolution
- Internal Heat wasting-thirst, Dryness-Heat vexing fullness: Lung-Stomach Heat-exuberance and fluid-injury producing dry-excessive drinking, heart-vexation dryness-Heat, body vexing fullness; adjunctive in Dryness-Heat wasting-thirst
V. Five Classical Formulas
1. Gua Lou Xie Bai Ban Xia Tang “Trichosanthes-Allium-Pinellia Decoction” (Jin Gui Yao Lue)
Composition: Quan Gua Lou · Xie Bai · Ban Xia · Bai Jiu. Action: unblock Yang and scatter binding, dissolve Phlegm and broaden the chest. Indication: Phlegm-turbid chest bi-obstruction — chest stuffiness and heart pain, chest-diaphragm oppression, shortness of breath. The premier chest-opening formula in TCM; Gua Lou’s role: the primary Phlegm-dissolving and chest-broadening drug; Xie Bai unblocks Yang-Qi and disperses Cold-Phlegm; Ban Xia dissolves Phlegm and harmonises Stomach; Bai Jiu amplifies the Yang-unblocking force.
2. Qing Qi Hua Tan Wan “Clear Qi and Resolve Phlegm Pill”
Composition: Gua Lou Ren · Huang Qin · Ban Xia · Chen Pi · Xing Ren · Fu Ling. Action: clear Heat and resolve Phlegm, regulate Qi and stop cough. Indication: Phlegm-Heat cough — yellow thick sticky phlegm, chest-diaphragm stuffiness and fullness, coughing phlegm without ease. Gua Lou Ren’s role: clears and washes away sticky Phlegm; Huang Qin clears Lung-Heat; Ban Xia resolves Phlegm and harmonises; the combination powerfully addresses the dual Phlegm-and-Heat mechanism.
3. Xiao Xian Xiong Tang “Minor Sink-the-Chest Decoction” (Shang Han Lun)
Composition: Quan Gua Lou · Huang Lian · Ban Xia. Action: clear Heat and resolve Phlegm, scatter binding and open the stuffiness. Indication: Phlegm-Heat binding — chest-epigastric stuffiness and fullness, xin xia pi ying (epigastric hardness), pain on pressing. A three-herb formula of exceptional structural elegance: Gua Lou clears Heat-Phlegm and broadens the chest; Huang Lian clears Heat and drains Fire; Ban Xia dissolves Phlegm and scatters binding; together they address the Phlegm-and-Heat mutual-binding pattern that produces the epigastric hardness-on-pressure presentation.
4. Gua Lou Zhi Shi Tang “Trichosanthes-Immature Orange Decoction”
Composition: Gua Lou · Zhi Shi · Jie Geng · Xing Ren · Huang Qin. Action: clear Heat and resolve Phlegm, descend Qi and broaden the chest. Indication: Lung-Heat with Phlegm exuberance — cough with dyspnoea, copious Phlegm, chest-diaphragm distension and fullness. Gua Lou + Zhi Shi provide the Phlegm-clearing and chest-broadening; Jie Geng opens the Lung and expels Phlegm; Xing Ren descends Qi and stops cough; Huang Qin clears Lung-Heat.
5. Run Fei San “Moisten-Lung Powder”
Composition: Gua Lou Ren · Bei Mu · Xing Ren · Mai Dong. Action: moisten Lung and stop cough, generate fluids and moisten Dryness. Indication: Lung-Dryness dry cough, little sticky phlegm, dry-sore throat, fluid-Yin deficiency constipation. Gua Lou Ren’s seed-oil lubricates the Lung and intestines; Bei Mu dissolves Phlegm and scatters binding; Xing Ren descends Qi and moistens Dryness; Mai Dong nourishes Lung-Stomach Yin.
VI. Four-Herb Differential
| Herb | Nature | Core emphasis | Unique advantage | Cannot do |
|---|---|---|---|---|
| Gua Lou | Sweet-mildly bitter, cold; Lung, Stomach, Large Intestine | Clear Heat-Phlegm + broaden chest + moisten intestines + scatter binding + dissolve sore toxins | The only Phlegm-clearing herb that simultaneously broadens the chest AND moistens the intestines; three-channel top-to-bottom coverage; the standard chest-bi herb | Moisten-Lung cough as specifically as Chuan Bei Mu; generate fluids as specifically as Tian Hua Fen; drain Lung and calm dyspnoea with diuresis as Sang Bai Pi |
| Chuan Bei Mu | Bitter-sweet, mildly cold; Lung, Heart channels | Moisten Lung + resolve Phlegm + scatter binding + dissolve carbuncle | Lung-moistening and Phlegm-dissolving strongest; specifically for chronic Yin-deficiency dry cough, Dryness-cough, and Xu-cough; no chest-broadening or laxative action | Broaden the chest; moisten intestines; address Phlegm-turbid chest obstruction; generate fluids for wasting-thirst |
| Tian Hua Fen (Gua Lou Root) | Sweet-mildly bitter, cold; Lung, Stomach channels | Clear Heat + generate fluids; dissolve swelling + expel pus | Generate fluids and relieve wasting-thirst strongest; dissolve swelling and expel pus for abscess formation; no Phlegm-dissolving, chest-broadening, or laxative action | Dissolve Phlegm; broaden chest; moisten intestines; address chest-bi |
| Sang Bai Pi | Sweet, cold; Lung channel | Drain Lung + calm dyspnoea; promote urination + reduce oedema | Drain Lung and calm dyspnoea with accompanying oedema strongest; also diuretic and oedema-reducing; Lung-Heat dyspnoea with oedema | Scatter binding; moisten intestines; broaden chest; resolve sore toxins |
| Gua Lou Pi vs Gua Lou Ren | Pi: light, ascends; Ren: moist, descends | Pi: clear Lung-Phlegm and broaden chest; Ren: moisten Lung-Dryness and lubricate intestines | Pi best for Phlegm-Heat chest stuffiness; Ren best for dry cough and intestinal-Dryness constipation | Pi: no laxative; Ren: chest-broadening weaker |
VII. Modern Pharmacology
Core active constituents: Trichosanthes saponins (primary cardioprotective component); flavonoids; alkaloids; plant oils and fatty acids (primary intestine-moistening component); polysaccharides; amino acids.
- Expectorant, antitussive, and anti-asthmatic: inhibits airway inflammation; thins mucus viscosity; relaxes bronchial smooth muscle; effectively relieves cough, copious phlegm, and dyspnoea; improves respiratory conditions
- Cardiovascular protection: dilates coronary arteries; improves myocardial blood supply; reduces vascular resistance; inhibits platelet aggregation; adjunctive in chest stuffiness, chest bi-obstruction, and myocardial ischaemia
- Gentle laxative: oil-rich seeds lubricate intestinal wall; promote intestinal peristalsis; gentle improvement of intestinal-Dryness constipation without stimulant laxative effect
- Anti-inflammatory and sore-resolving: inhibits inflammatory responses; reduces skin carbuncle-sore swellings, breast inflammation; promotes inflammatory exudate resolution
- Hypoglycaemic and antioxidant: improves metabolic function; scavenges free radicals; adjunctive in Dryness-Heat wasting-thirst; enhances antioxidant capacity
VIII. Dosage and Safety
Suitable populations: Lung-Heat with yellow thick sticky phlegm, copious Phlegm difficult to expectorate; chest stuffiness and oppression, chest-bi Qi-stagnation binding, chest-before-the-sternum pain; Lung-Dryness dry cough, fluid-Yin depletion dry stool, habitual intestinal-Dryness constipation; breast carbuncle, Lung carbuncle, sore-Heat-toxin binding; Lung-Stomach Dryness-Heat, vexing thirst and wasting-thirst.
Dosage: decoction: Quan Gua Lou 9–15g; Gua Lou Pi 6–10g; Gua Lou Ren 10–15g (crushed before decocting). Processing selection: moisten-Dryness stop-cough — honey-fried Gua Lou; clear Heat resolve Phlegm — raw Gua Lou. Do not use in excessive doses or long-term to avoid Cold-damaging Spleen and slipping intestine excess.
Contraindications:
- Spleen-Stomach deficiency-Cold, loose stool and diarrhoea: Gua Lou’s cold moist nature worsens Spleen-Stomach deficiency-Cold; causes diarrhoea, abdominal bloating, and abdominal cold-pain; contraindicated
- Cold-Damp Phlegm and Damp-Phlegm cough-dyspnoea: Cold-type Phlegm-Damp cough using the cold-cooling Gua Lou will worsen Phlegm-Damp congealing, aggravating cough-dyspnoea; contraindicated
- Low blood pressure and bleeding tendency: Gua Lou’s vasodilating and antiplatelet actions may worsen dizziness and bleeding; use with caution
- Pregnancy, constitutional chronic diarrhoea: cold-moist slipping nature; risks Spleen-Yang damage in constitutionally weak patients with chronic diarrhoea; use with caution
- Incompatibilities (Shi Ba Fan): CRITICAL — Gua Lou conflicts with Wu Tou (Aconite root, including Chuan Wu, Cao Wu, Fu Zi): ABSOLUTELY PROHIBITED. This is one of the most clinically important Eighteen Incompatibilities prohibitions. Also: aversion to Gan Jiang and Niu Xi — avoid combining
