Xi Gua Cui Yi 西瓜翠衣 — Chinese Herbal Medicine

Xi Gua Cui Yi (西瓜翠衣) At a Glance

• Herb: Xi Gua Cui Yi
• Chinese name: 西瓜翠衣 (Xi Gua Cui Yi)
• Latin name: Exocarpium Citrulli
• Nature: Cold
• Taste: Sweet, Acid
• Meridian: Lung
• Category: Clear Qi Level Heat

Xi Gua Cui Yi is the dried green exocarp of the watermelon (Citrullus lanatus), distinguished from the thicker Xi Gua Pi by its thinner, jade-green outer layer. Its cold nature and sweet-sour flavor make it particularly suited to clearing Qi-level and summer-heat while generating fluids and relieving thirst. It serves as a gentle yet effective remedy for febrile disorders, summer-heat patterns, and fluid depletion following illness.

Actions & Therapeutic Effects

• Clears summer-heat and relieves thirst
• Clears Qi-level heat from the Lung and Stomach
• Generates fluids and nourishes Yin
• Promotes urination and resolves dampness
• Reduces swelling and alleviates edema
• Cools the Blood and clears heat toxin from the skin

Clinical Applications in TCM

• Summer-heat with fever, thirst, and scanty dark urine — combine with Lian Qiao (连翘), Zhu Ye (竹叶), and Lu Gen (芦根)
• Qi-level heat with high fever, sweating, and irritability — use with Shi Gao (石膏) and Zhi Mu (知母)
• Lung heat with dry cough, hoarse voice, and thirst — pair with Sang Ye (桑叶) and Tian Hua Fen (天花粉)
• Edema and difficult urination from damp-heat — combine with Che Qian Zi (车前子) and Fu Ling (茯苓)
• Mouth sores and oral ulcers due to Heart and Stomach fire — use with Huang Lian (黄连) and Zhu Ye (竹叶)
• Post-febrile fluid deficiency with lingering thirst — pair with Mai Dong (麦冬) and Yu Zhu (玉竹)

Precautions & Safety

• Dosage: 15–30 g dried in decoction; fresh juice 60–120 g; topical paste may be applied to skin lesions
• Contraindicated in Spleen-Stomach cold deficiency with loose stools or diarrhea; use cautiously in patterns without heat; avoid large doses during pregnancy

Classical TCM Formulas

• Xi Gua Cui Yi Cha (西瓜翠衣茶): watermelon rind decoction — for Summerheat thirst and fever.
• Qing Shu Yi Qi Tang (清暑益气汤): Xi Yang Shen, Mai Men Dong, Zhi Mu, Gan Cao, Jing Mi, Xi Gua Cui Yi, Huang Lian, Zhu Ye, He Geng, Shi Hu. Source: Wen Bing Tiao Bian.
• Wang Shi Qing Shu Yi Qi Tang (王氏清暑益气汤) features Xi Gua Cui Yi prominently.

Herb Combinations

• Xi Gua Cui Yi (西瓜翠衣) + Jin Yin Hua (金银花) + Bo He (薄荷): the Summerheat-clearing tea for fever, thirst, and irritability.
• Xi Gua Cui Yi (西瓜翠衣) + Zhu Ye (竹叶) + Shi Gao (石膏): the Qing Shu Yi Qi Tang approach — clears Summerheat and generates fluids.
• Xi Gua Cui Yi (西瓜翠衣) + Lu Gen (芦根) + Mai Men Dong (麦门冬): generates fluids for severe Summerheat thirst.

Pharmacology & Research

Cucurbitacins: anti-inflammatory and mild antitumor activity.
Citrulline and arginine: promote diuresis and support nitric oxide synthesis and vasodilation.
Flavonoids (luteolin, apigenin): antioxidant, anti-inflammatory, and antipyretic effects.
Pectin and polysaccharides: mild immunomodulatory and mucosal-protective activity.
Vitamin C and B-complex: support immune function, tissue repair, and antioxidant defense.

Classical Descriptions

• “Xi Gua relieves summer-heat, quenches thirst, promotes urination, and resolves drunkenness; its rind clears heat from the skin and muscles.” — Bencao Gangmu (本草纲目), Li Shizhen, 1596