Gua Lou Pi 瓜蒌皮 — Chinese Herbal Medicine

Gua Lou Pi (瓜蒌皮) At a Glance

• Herb: Gua Lou Pi
• Chinese name: 瓜蒌皮 (Gua Lou Pi)
• Latin name: Trichosanthis Pericarpium
• Nature: Cold
• Taste: Bitter, Sweet
• Meridian: Lung
• Category: Resolve Phlegm Heat

Gua Lou Pi is the dried pericarp of Trichosanthes kirilowii, separated from the seeds and pulp to emphasise its action on the upper body. Its cold nature and sweet-bitter taste make it well-suited to phlegm-heat patterns lodging in the Lung and obstructing the chest. Compared to the whole fruit (Gua Lou), the pericarp is lighter in texture and more focused on dispersing and opening rather than moistening downward.

Actions & Therapeutic Effects

• Clears Lung heat and transforms phlegm — addresses thick, yellow, difficult-to-expectorate sputum from phlegm-heat in the Lung
• Expands the chest and relieves chest bi — unbinds constraint in the chest-diaphragm region caused by phlegm obstructing the yang qi
• Moistens the Lung and stops cough — gentle moisture prevents dryness from heat injuring Lung yin
• Soothes swelling and disperses nodules — assists in early-stage Lung or breast abscesses where phlegm and heat bind together

Clinical Applications in TCM

• Phlegm-heat cough with thick yellow sputum: combine with Zhe Bei Mu (浙贝母), Huang Qin (黄芩), and Jie Geng (桔梗)
• Chest bi (xiong bi) with phlegm blocking chest yang: used in Gua Lou Xie Bai Ban Xia Tang (瓜蒌薤白半夏汤) — Trichosanthes-Allium-Pinellia Decoction
• Chest oppression and epigastric fullness from phlegm-heat: pair with Huang Lian (黄连) and Ban Xia (半夏) as in Xiao Xian Xiong Tang (小陷胸汤)
• Dry Lung cough with scanty sputum: combine with Sang Ye (桑叶), Mai Dong (麦冬), and Sha Shen (沙参)
• Early breast abscess or Lung abscess: pair with Jin Yin Hua (金银花), Pu Gong Ying (蒲公英), and Jie Geng (桔梗)

Precautions & Safety

• Dosage: 6–12 g in decoction; up to 15 g in severe phlegm-heat
• Incompatible with Wu Tou (乌头) and its processed forms (Zhi Chuan Wu, Zhi Cao Wu, Fu Zi) — classical eighteen incompatibilities (十八反)
• Contraindicated in cold-phlegm patterns (white, watery, profuse sputum with cold signs) — cold nature will aggravate
• Use with caution in Spleen-Stomach deficiency with loose stools; combine with Bai Zhu (白术) or Chen Pi (陈皮) if necessary
• Caution during pregnancy: large doses may have a descending, dispersing effect

Classical TCM Formulas

• Gua Lou Xie Bai Bai Jiu Tang (瓜蒌薤白白酒汤): Gua Lou Shi, Xie Bai, Bai Jiu — Chest Bi with Yang obstruction. Source: Jin Gui Yao Lue.
• Xiao Xian Xiong Tang (小陷胸汤): Huang Lian, Ban Xia, Gua Lou Shi — Heat-Phlegm in the chest. Source: Shang Han Lun.
• Gua Lou Pi decoction alone: for Phlegm-Heat cough with chest oppression.

Herb Combinations

• Gua Lou Pi (瓜蒌皮) + Xie Bai (薤白) + Ban Xia (半夏): the Gua Lou Xie Bai Ban Xia Tang trio — unblocks Yang, transforms Phlegm, and disperses chest masses.
• Gua Lou Pi (瓜蒌皮) + Huang Lian (黄连) + Ban Xia (半夏): the Xiao Xian Xiong Tang approach — clears Heat-Phlegm in the chest.
• Gua Lou Pi (瓜蒌皮) + Gua Lou Ren (瓜蒌仁): the whole-fruit approach — Pi clears and transforms, Ren moistens and unblocks.

Pharmacology & Research

Expectorant: saponin constituents reduce sputum viscosity and stimulate bronchial secretion, facilitating expectoration.
Anti-inflammatory: flavonoids and polysaccharides suppress prostaglandin synthesis and inhibit inflammatory cytokine release.
Cardiovascular: dilates coronary arteries and improves myocardial perfusion, supporting the classical use in chest bi.
Antimicrobial: aqueous extract inhibits Staphylococcus aureus, Streptococcus, and Mycobacterium tuberculosis in vitro.
Antitumour: triterpene compounds demonstrate cytotoxic activity against lung and breast cancer cell lines in preliminary studies.

Classical Descriptions

• “主胸痹，不得卧，心痛彻背者。” — *Jin Kui Yao Lue* (金匱要略), Zhang Zhongjing, c. 220 CE (describing Gua Lou in chest bi formulas); the pericarp’s distinct actions elaborated in *Ben Cao Gang Mu* (本草纲目), Li Shizhen, 1578: “润肺燥，降火，治咳嗽，涤痰结，利咽喉。”