Guilin Xi Gua Shuang

Guilin Watermelon Frost · 桂林西瓜霜

Also known as: Xi Gua Shuang, Watermelon Frost Powder, 桂林西瓜霜喷剂,

A topical powder formula used for sore throat, mouth ulcers, swollen gums, and oral inflammation caused by Heat and toxins in the Lung and Stomach. It clears Heat, resolves toxins, reduces swelling, and relieves pain in the mouth and throat. One of the most widely used Chinese patent medicines for oral and throat conditions.

Origin Yáng Yī Dà Quán (疡医大全) by Gù Shìchéng (顾世澄), with modern compound formulation recorded in the Chinese Pharmacopoeia (中华人民共和国药典) — Qīng dynasty, 1760 CE (original watermelon frost substance); modern compound formulation
Composition 14 herbs
Xi Gua
King
Xi Gua
Shan Dou Gen
King
Shan Dou Gen
Huang Qin
Deputy
Huang Qin
Huang Lian
Deputy
Huang Lian
Huang Qi
Deputy
Huang Qi
Da Huang
Assistant
Da Huang
She Gan
Assistant
She Gan
Zh
Assistant
Zhe Bei Mu (Zhejiang Fritillaria Bulb)
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Explore composition

Educational content Consult qualified TCM practitioners for diagnosis and treatment

Patterns Addressed

In TCM, symptoms don't appear randomly — they cluster into recognizable patterns of disharmony that reveal what's out of balance in the body. Guilin Xi Gua Shuang is designed to correct these specific patterns.

Why Guilin Xi Gua Shuang addresses this pattern

When Heat-toxin accumulates in the Lung and Stomach, it flares upward along the channels to the throat, mouth, and gums, causing acute inflammation, swelling, pain, and ulceration. This is the primary pattern that Gui Lin Xi Gua Shuang addresses. The formula's King herbs (Xi Gua Shuang and Shan Dou Gen) directly clear Heat-toxin from the affected area, while the three Huang Deputies drain Fire systemically. Da Huang purges Heat downward, and Bing Pian guides the formula to the local site of inflammation. The combined action powerfully clears Heat-toxin from above while draining it from below, resolving the acute inflammation.

A practitioner would look for one or more of these signs

Sore Throat

Acute, burning sore throat with difficulty swallowing

Mouth Ulcers

Painful mouth sores with red borders

Swollen Gums

Red, swollen, painful gums that may bleed

Tonsillitis

Swollen, inflamed tonsils

Corneal Ulcers

Ulcers on tongue or inner cheeks

Commonly Prescribed For

These conditions can arise from the patterns above. A practitioner would consider Guilin Xi Gua Shuang when these conditions are specifically caused by those patterns — not for all cases of these conditions.

Arises from: Heat-Toxin Bright Yang Stomach Heat

TCM Interpretation

In TCM, mouth ulcers (oral aphthous ulcers) are understood as a manifestation of internal Heat, most commonly arising from the Stomach and Spleen. The Stomach channel traverses the gums and mouth, so when excessive Heat accumulates in the Stomach (from diet, stress, or constitutional factors), it rises along the channel and 'burns' the oral mucosa, creating painful sores. In some cases, Yin deficiency in the Kidney or Heart creates a 'deficiency Fire' that also flares upward, though this formula primarily addresses excess Heat patterns. The location, appearance, and accompanying symptoms of the ulcers help differentiate the underlying pattern.

Why Guilin Xi Gua Shuang Helps

Gui Lin Xi Gua Shuang is one of the most widely used remedies for mouth ulcers in China. Applied directly to the sore, Xi Gua Shuang (the mineral frost) provides immediate cooling and pain relief while clearing local Heat-toxin. Bing Pian penetrates the tissue to deliver relief deep into the ulcer. The three Huang herbs (Huang Qin, Huang Lian, Huang Bai) address the internal Stomach Heat that generated the ulcer in the first place. Qing Dai cools the Blood at the ulcer site, reducing redness and promoting healing. Clinical studies have shown the formula to be effective in reducing pain and accelerating healing of oral ulcers.

Also commonly used for

Tonsillitis

Acute and chronic tonsillitis

Corneal Ulcers

Stomatitis, oral mucosal inflammation

Hoarse Voice

Laryngitis with voice hoarseness

Toothache

Toothache from gum inflammation

Skin Burns

Minor superficial burns where skin is intact

What This Formula Does

Every TCM formula has a specific set of actions — here's what Guilin Xi Gua Shuang does in the body, explained in both everyday and TCM terms

Therapeutic focus

In practical terms, Guilin Xi Gua Shuang is primarily used to support these areas of health:

TCM Actions

In TCM terminology, these are the specific therapeutic actions that Guilin Xi Gua Shuang performs to restore balance in the body:

How It Addresses the Root Cause

TCM doesn't just suppress symptoms — it aims to resolve the underlying imbalance. Here's how Guilin Xi Gua Shuang works at the root level.

Xi Gua Shuang addresses conditions where Heat-toxin or Fire from the Lung and Stomach channels flares upward to the throat, mouth, and gums. In TCM, the throat is the gateway of the Lungs, and the mouth and gums are closely connected to the Stomach. When pathogenic Heat or Fire accumulates in these organ systems, it rises along the channels, scorching the delicate tissues of the upper body. This produces the hallmark symptoms: a red, swollen, painful throat (known as "throat blockage" or hou bi 喉痹), mouth sores (kou chuang 口疮), gum swelling and bleeding, and tonsillitis (ru e 乳蛾, literally "breast moth," describing the swollen tonsils).

The underlying pattern is one of excess Heat or Fire-toxin in the upper body. This may arise from external Wind-Heat invasion that concentrates in the throat, from accumulated internal Stomach Fire that blazes upward, or from overindulgence in rich, spicy, or heating foods. The Heat dries and damages the local tissue, causing redness, swelling, ulceration, and pain. Because the Heat is concentrated in the upper orifices (mouth, throat, eyes), the treatment strategy calls for strongly cold, salty substances that can directly quench Fire, soften hardness, reduce swelling, and resolve toxins right at the site of damage.

Xi Gua Shuang works by applying intense cold and salty properties directly to the inflamed tissue. Its cold nature directly opposes and extinguishes the pathogenic Fire, while its salty taste has a softening, dissolving effect on swollen, hardened tissue. This dual action explains why classical doctors praised it as the "sacred medicine of throat medicine" (hou ke sheng yao 喉科圣药).

Formula Properties

Every formula has an inherent temperature, taste, and affinity for specific organs — these properties determine how it interacts with the body

Overall Temperature

Cold

Taste Profile

Predominantly salty and cold, with a cooling, slightly sweet undertone from the watermelon component. The salty taste softens hardness and dissolves swelling, while the cold nature directly quenches pathogenic Fire.

Ingredients

14 herbs

The herbs that make up Guilin Xi Gua Shuang, organized by their role in the prescription

King — Main ingredient driving the formula
Deputy — Assists and enhances the King
Assistant — Supports or moderates other herbs
Envoy — Directs the formula to its target
Kings — Main ingredient driving the formula
Xi Gua

Xi Gua

Watermelons

Dosage 1.2g (per unit dose)
Temperature Cold
Taste Sweet
Organ Affinity Urinary Bladder, Stomach, Heart
Preparation Prepared by crystallization of mirabilite through watermelon rind

Role in Guilin Xi Gua Shuang

The principal ingredient and namesake of the formula. Salty and cold in nature, it enters the Lung, Stomach, and Large Intestine channels. It powerfully clears Heat, drains Fire, reduces swelling, and relieves pain in the throat and mouth. As the substance with the largest proportion in the formula, it directly addresses the core pathomechanism of Heat-toxin accumulating in the upper body.
Shan Dou Gen

Shan Dou Gen

Bushy Sophora roots

Dosage 0.1g (per unit dose)
Temperature Cold
Taste Bitter
Organ Affinity Heart, Large Intestine, Lungs

Role in Guilin Xi Gua Shuang

Bitter and cold, it enters the Lung and Stomach channels. A powerful Heat-clearing and toxin-resolving herb with specific affinity for the throat. It strongly clears Heat-toxin from the upper body, making it particularly effective for swollen, painful throat conditions and oral sores. Works alongside Xi Gua Shuang as a co-King herb to address the primary pathomechanism.
Deputies — Assists and enhances the King
Huang Qin

Huang Qin

Baikal skullcap roots

Dosage 0.1g (per unit dose)
Temperature Cold
Taste Bitter
Organ Affinity Gallbladder, Heart, Large Intestine, Lungs, Small Intestine, Spleen

Role in Guilin Xi Gua Shuang

Bitter and cold, it clears Heat and dries Dampness, particularly in the upper body and Lung. It reinforces the King herbs by broadly clearing Heat from the Lung and Stomach, draining Fire, and resolving toxins. Its affinity for the upper burner makes it especially relevant for throat and oral inflammation.
Huang Lian

Huang Lian

Goldthread rhizomes

Dosage 0.1g (per unit dose)
Temperature Cold
Taste Bitter
Organ Affinity Gallbladder, Heart, Large Intestine, Liver, Spleen, Stomach

Role in Guilin Xi Gua Shuang

Bitter and cold, it is one of the strongest Heat-clearing and Dampness-drying herbs in the materia medica. It drains Fire from the Heart and Stomach, resolves toxins, and has strong antibacterial properties. Supports the King herbs by clearing Heat from the middle burner, which is a common source of Fire that flares upward to the mouth and throat.
Huang Qi

Huang Qi

Milkvetch roots

Dosage 0.1g (per unit dose)
Temperature Warm
Taste Sweet
Organ Affinity Lungs, Spleen

Role in Guilin Xi Gua Shuang

Bitter and cold, it clears Heat, dries Dampness, and drains Fire, particularly from the lower burner. Together with Huang Qin and Huang Lian, it forms a powerful trio that clears Heat-toxin from all three burners, ensuring comprehensive Fire-draining across the entire body to prevent recurrence.
Assistants — Supports or moderates other herbs
Da Huang

Da Huang

Rhubarb

Dosage 0.1g (per unit dose)
Temperature Cold
Taste Bitter
Organ Affinity Spleen, Stomach, Large Intestine, Liver, Pericardium

Role in Guilin Xi Gua Shuang

Bitter and cold, it purges Heat downward through the bowels. By draining accumulated Heat from the Stomach and intestines, it provides an exit route for the pathogenic Fire that has flared upward. This downward-directing action complements the local Heat-clearing action of the other herbs and prevents Heat from lingering internally.
She Gan

She Gan

Blackberry Lily rhizomes

Dosage 0.1g (per unit dose)
Temperature Cold
Taste Bitter
Organ Affinity Lungs

Role in Guilin Xi Gua Shuang

Bitter and cold, it clears Heat and resolves toxins with a specific tropism for the throat. It is particularly effective at dispersing accumulation in the throat area and resolving Phlegm-Heat that may be contributing to swelling and obstruction. Directly supports the King herbs in addressing throat symptoms.
Zh

Zhe Bei Mu (Zhejiang Fritillaria Bulb)

Dosage 0.2g (per unit dose)

Role in Guilin Xi Gua Shuang

Bitter and cold, it clears Heat, transforms Phlegm, and dissipates nodules. In this formula it addresses any Phlegm-Heat component contributing to swollen tonsils or throat nodules. Its ability to soften hardness and dissipate accumulation makes it valuable for cases with visible swelling of the tonsils or lymph nodes.
Qing Dai

Qing Dai

Natural indigo

Dosage 0.1g (per unit dose)
Temperature Cold
Taste Salty
Organ Affinity Stomach, Liver, Lungs

Role in Guilin Xi Gua Shuang

Salty and cold, it clears Heat, resolves toxins, cools the Blood, and reduces swelling. It is particularly effective for topical application on inflamed, ulcerated tissues. Its Blood-cooling action addresses the redness, swelling, and bleeding that may accompany oral and throat inflammation.
Peng Sha

Peng Sha

Borax

Dosage 0.1g (per unit dose)
Temperature Cool
Taste Salty, Sweet
Organ Affinity Stomach, Lungs
Preparation Used in calcined form (煅硼砂)

Role in Guilin Xi Gua Shuang

Sweet and salty, cool in nature, it clears Heat, resolves toxins, and has strong topical antiseptic properties. When applied to the mouth and throat, it directly addresses local infection and inflammation. The calcined form (Duan Peng Sha) is used to reduce irritation while maintaining its Heat-clearing and toxin-resolving action.
Wu

Wu Huan Zi (Sapindus Fruit, charcoal)

Dosage 0.1g (per unit dose)
Preparation Used in charcoal form (炭)

Role in Guilin Xi Gua Shuang

Bitter and slightly toxic, when charred it gains astringent and hemostatic properties. It resolves toxins and reduces swelling. In charcoal form it helps control bleeding from inflamed gums or ulcerated oral tissues while contributing to toxin resolution.
Bo He

Bo He

Wild mint

Dosage 0.01g (per unit dose)
Temperature Cool
Taste Pungent
Organ Affinity Liver, Lungs

Role in Guilin Xi Gua Shuang

Pungent and cool, menthol (the refined crystalline extract of mint) disperses Wind-Heat from the head and throat, provides a cooling and pain-relieving sensation on contact, and helps vent Heat outward. Its aromatic quality also helps open the airways and provides immediate symptomatic relief from throat irritation.
Envoys — Directs the formula to its target
Bing Pian

Bing Pian

Borneol

Dosage 0.05g (per unit dose)
Temperature Cool
Taste Bitter
Organ Affinity Spleen, Heart, Lungs

Role in Guilin Xi Gua Shuang

Pungent and bitter, slightly cold, it opens orifices, clears Heat, and relieves pain. As the envoy herb, Bing Pian's aromatic, penetrating nature guides the other herbs to the affected local tissues, enhancing their absorption and therapeutic effect. It also provides immediate analgesic and anti-inflammatory action on contact with inflamed oral and throat tissues.
Gan Cao

Gan Cao

Liquorice

Dosage 0.29g (per unit dose)
Temperature Neutral
Taste Sweet
Organ Affinity Heart, Lungs, Spleen, Stomach

Role in Guilin Xi Gua Shuang

Sweet and neutral, it harmonizes all the other herbs in the formula, moderates their bitter and cold properties, and contributes its own mild Heat-clearing and toxin-resolving action. Its sweet flavor also soothes irritated throat and oral tissues, providing a demulcent effect that complements the formula's primary cooling actions.

Why This Combination Works

How the herbs in Guilin Xi Gua Shuang complement each other

Overall strategy

This formula addresses Heat-toxin that has accumulated in the Lung and Stomach and flared upward to the mouth, throat, and gums. The prescription combines powerful topical Heat-clearing and toxin-resolving agents with aromatic penetrating substances to deliver therapeutic action directly to the affected local tissues.

King herbs

Xi Gua Shuang (Watermelon Frost) is the primary King herb, carrying the largest proportion in the formula. Its salty, cold nature powerfully clears Heat, drains Fire, reduces swelling, and relieves pain, with a direct affinity for the Lung and Stomach channels where the pathogenic Heat originates. Shan Dou Gen (Vietnamese Sophora Root) serves as a co-King, one of the strongest throat-specific Heat-clearing and toxin-resolving herbs, directly targeting the core symptom of swollen, painful throat.

Deputy herbs

The three Huang (yellow) herbs form a classical combination: Huang Qin clears Heat from the upper burner and Lung, Huang Lian drains Fire from the Heart and Stomach (the middle burner source of upward-flaring Fire), and Huang Bai clears Heat from the lower burner. Together they provide comprehensive Fire-draining across all three burners, ensuring that the Heat-toxin is cleared systemically rather than just locally suppressed.

Assistant herbs

Da Huang (reinforcing assistant) purges accumulated Heat downward through the bowels, providing an essential exit route for the Fire. She Gan and Zhe Bei Mu (reinforcing assistants) add throat-specific actions: She Gan disperses accumulation in the throat while Zhe Bei Mu transforms Phlegm-Heat and dissipates nodules in swollen tonsils. Qing Dai cools the Blood to address redness and bleeding. Peng Sha (calcined borax) and Wu Huan Zi charcoal provide topical antiseptic and mild astringent action. Bo He Nao (menthol) disperses Wind-Heat and provides immediate cooling pain relief.

Envoy herbs

Bing Pian (Borneol) is the formula's primary envoy. Its aromatic, penetrating nature opens the local tissues and guides the other medicinals deep into inflamed oral and throat mucosa, dramatically enhancing their absorption and effect. Gan Cao harmonizes the entire formula's many bitter, cold ingredients, moderates their harshness on the Stomach, and adds a soothing demulcent quality to irritated tissues.

Notable synergies

The pairing of Xi Gua Shuang with Bing Pian is the formula's signature combination: Xi Gua Shuang provides the core Fire-draining and swelling-reducing action, while Bing Pian's penetrating aromatic quality ensures this action reaches deep into inflamed tissues. The Huang Qin, Huang Lian, and Huang Bai trio (San Huang) is a classical combination that comprehensively clears Damp-Heat and Fire across all three burners. She Gan paired with Zhe Bei Mu targets throat conditions from two angles: dispersing accumulation and transforming Phlegm.

How to Prepare

Traditional preparation instructions for Guilin Xi Gua Shuang

The base ingredient, watermelon frost (Xi Gua Shuang), is prepared by cutting open an unripe watermelon, removing the flesh, filling the cavity with mirabilite (Pi Xiao), sealing it, and hanging it in a cool, ventilated place. After approximately 10 days, white crystalline frost seeps through the watermelon rind and is scraped off. This frost is then ground to a fine powder and combined with the other powdered ingredients.

The finished compound powder is applied topically by spraying, blowing, or dusting onto the affected area in the mouth, throat, or on skin lesions. For external use, apply an appropriate amount to the affected area several times daily. For severe cases, it may also be taken internally at 1 to 2 grams per dose, three times daily. Avoid eating or drinking for 30 minutes after application.

Common Modifications

How practitioners adapt Guilin Xi Gua Shuang for specific situations

Added
Niu Bang Zi

6-9g, disperses Wind-Heat and benefits the throat

Jie Geng

3-6g, opens and directs herbs to the throat area

Niu Bang Zi adds a strong Wind-Heat dispersing and throat-clearing action, while Jie Geng acts as a guide herb directing the formula's action upward to the throat, enhancing efficacy for severe tonsillitis.

Educational content — always consult a qualified healthcare provider or TCM practitioner before using any herbal formula.

Contraindications

Situations where Guilin Xi Gua Shuang should not be used or requires extra caution

Avoid

Yin deficiency patterns with diphtheria-like white membrane (阴虚白喉). Classical sources explicitly warn against using Xi Gua Shuang in this condition, as its cold and salty nature can further damage Yin fluids. The classical formula Yu Yao Shi (玉钥匙) specifically notes: '阴虚白喉忌用' (contraindicated in Yin-deficient diphtheria).

Avoid

Spleen and Stomach deficiency Cold patterns with loose stools or diarrhea. Xi Gua Shuang is cold in nature with Glauber's salt (a purgative mineral) as a primary component, which can further weaken an already cold and deficient digestive system.

Avoid

Cold-type sore throat caused by Wind-Cold invasion without Heat signs. This formula is designed exclusively for Heat-pattern throat conditions. Misapplication in Cold patterns can trap the pathogen and worsen symptoms.

Caution

Prolonged or excessive use. Because the main component is essentially sodium sulfate (a mineral salt), long-term topical use may cause irritation or electrolyte imbalance if swallowed in large amounts. It is intended for short-term symptomatic relief.

Caution

People with chronic kidney disease or conditions requiring sodium restriction should use with caution, as the primary constituent is a sodium sulfate-based mineral salt.

Special Populations

Important considerations for pregnancy, breastfeeding, and pediatric use

Pregnancy

Use with caution during pregnancy. The primary component of Xi Gua Shuang is derived from Mang Xiao (Glauber's salt/sodium sulfate), which is a known purgative and is traditionally classified as cautioned during pregnancy due to its downward-draining action. While Xi Gua Shuang is primarily used topically (blown or sprayed onto the throat and mouth), small amounts are inevitably swallowed. Occasional topical use for acute symptoms is unlikely to cause harm, but prolonged or heavy use should be avoided. Pregnant women should consult a qualified practitioner before use.

Breastfeeding

Generally considered acceptable for short-term topical use during breastfeeding. Xi Gua Shuang is applied locally to the throat and mouth, and only minimal amounts are absorbed systemically. The sodium sulfate base is not expected to transfer to breast milk in clinically significant amounts from topical oral use. However, mothers should avoid excessive or prolonged use and should not swallow large quantities intentionally. If symptoms persist beyond a few days, consult a practitioner.

Children

Xi Gua Shuang has traditionally been used for pediatric conditions including childhood thrush (e gou chuang 鹅口疮) and is generally considered suitable for children when used topically. For children, reduce the amount applied: approximately half the adult dose is appropriate. Young children should be supervised during application to prevent inhalation of the powder, which can cause choking or coughing. For infants and toddlers, a very small amount can be dabbed onto the affected area with a clean cotton swab rather than sprayed. Children should be monitored for any signs of irritation. Use should not exceed 3-5 days without professional guidance.

Drug Interactions

If you are taking pharmaceutical medications, be aware of these potential interactions with Guilin Xi Gua Shuang

No major drug interactions have been extensively documented for topical Xi Gua Shuang. However, the following theoretical considerations apply:

  • Sodium-sensitive medications: Since the primary component is sodium sulfate, if significant amounts are swallowed (particularly with the internal use of compound formulations), it could theoretically affect individuals on sodium-restricted diets or those taking medications for hypertension, heart failure, or kidney disease.
  • Anticoagulants/Antiplatelets: Some modern compound formulations of Xi Gua Shuang contain Da Huang (rhubarb), which has mild blood-activating properties and could theoretically enhance the effects of anticoagulant medications if taken internally in significant doses.
  • Concurrent topical medications: Avoid applying other topical oral medications simultaneously at the same site, as interactions between the mineral salt base and other topical agents have not been studied. Space applications at least 30 minutes apart.

Usage Guidance

Practical advice for getting the most out of Guilin Xi Gua Shuang

Best time to take

Apply to the affected area after meals and before bed, 3-6 times daily as needed. Do not eat or drink for 30 minutes after application.

Typical duration

Acute use: 3-7 days. If symptoms do not improve within 3 days, or worsen, consult a healthcare practitioner.

Dietary advice

While taking Xi Gua Shuang, avoid hot, spicy, fried, and greasy foods, as these can generate further internal Heat and counteract the formula's cooling action. Alcohol and strong stimulants like coffee should also be minimized. Favor bland, cooling foods such as congee, mung bean soup, pear, cucumber, and winter melon. Do not eat or drink for at least 30 minutes after application to allow the medicine to act on the affected area. Cold and raw foods should be consumed in moderation if there is underlying Spleen weakness.

Guilin Xi Gua Shuang originates from Yáng Yī Dà Quán (疡医大全) by Gù Shìchéng (顾世澄), with modern compound formulation recorded in the Chinese Pharmacopoeia (中华人民共和国药典) Qīng dynasty, 1760 CE (original watermelon frost substance); modern compound formulation

Classical Texts

Key passages from the classical Chinese medical texts that first described Guilin Xi Gua Shuang and its clinical use

Gu Shicheng (顾世澄), Yang Yi Da Quan (《疡医大全》, Complete Collection of Sore Medicine), Qing Dynasty (1760):

Original: 「西瓜霜,治咽喉口齿,双蛾喉痹,命在须臾。」

Translation: "Watermelon Frost treats diseases of the throat, mouth, and teeth, including bilateral tonsillitis and throat blockage [conditions where] life hangs by a thread."


Hou Sha Zheng Zhi Gai Yao (《喉痧症治概要》, Essentials of Treating Throat Rashes), formula Yu Yao Shi (玉钥匙, Jade Key):

Original: 「治一切喉证,肿痛白腐,退炎消肿:西瓜霜五钱,西月石五钱,飞朱砂六分,僵蚕五分,冰片五分。研极细末,吹患处。阴虚白喉忌用。」

Translation: "Treats all throat conditions with swelling, pain, and white putrefaction, reducing inflammation and swelling: Xi Gua Shuang 5 qian, borax 5 qian, prepared cinnabar 6 fen, Jiang Can (silkworm) 5 fen, borneol 5 fen. Grind into an extremely fine powder and blow onto the affected area. Contraindicated in Yin-deficient diphtheria."

Historical Context

How Guilin Xi Gua Shuang evolved over the centuries — its origins, lineage, and place in the broader tradition of Chinese medicine

Xi Gua Shuang (Watermelon Frost) has a history of over 200 years in Chinese medicine. It was first formally recorded by the Qing Dynasty physician Gu Shicheng (顾世澄, courtesy name Lianjiang 练江) in his monumental work Yang Yi Da Quan (《疡医大全》, 1760), a 40-volume compendium of external medicine. Gu, a native of Wuhu in Anhui province who practiced in Yangzhou for over 40 years, came from a multi-generational medical family and was renowned for his expertise in surgical and external medicine.

The traditional preparation method is a remarkable example of Chinese pharmaceutical ingenuity. A fresh watermelon is cut open, the flesh is partially scooped out, and the cavity is filled with Mang Xiao (mirabilite/Glauber's salt). The melon is then sealed, placed in a clay vessel, and stored in a cool, ventilated location. Over days to weeks, a white crystalline "frost" gradually seeps through the watermelon rind and precipitates on the outer surface of the container. This frost is carefully brushed off and collected as the finished medicine. Classical texts described this process as "the handiwork of nature" (天工造化).

Xi Gua Shuang earned the revered title "Sacred Medicine of Throat Medicine" (喉科圣药) and became a cornerstone of the TCM throat medicine (hou ke 喉科) tradition. In modern times, the Guilin Sanjin Pharmaceutical Company developed it into the widely popular compound preparation "Guilin Xi Gua Shuang" (桂林西瓜霜), which adds additional Heat-clearing and toxin-resolving herbs such as Huang Lian, Huang Qin, Shan Dou Gen, She Gan, and Bing Pian to enhance the original formula's actions. This modern spray and lozenge form has become one of the most recognized over-the-counter Chinese medicines throughout East and Southeast Asia for mouth ulcers and sore throats.

Modern Research

A published study investigating the pharmacological effects or clinical outcomes of Guilin Xi Gua Shuang

1

Comparison between Watermelon Frost and Ribavirin Aerosol in the Treatment of Oral Herpes in Hand, Foot and Mouth Disease (Clinical Trial, 2020)

Biomedical Research of International, 2020

A clinical trial comparing watermelon frost spray with ribavirin aerosol in 353 children with mild hand, foot, and mouth disease. The watermelon frost group showed faster disappearance of oral ulcers (4.3 days vs. 5.5 days, p<0.0036) and superior clinical outcomes after 5 days of treatment compared to ribavirin.

Link

Research on TCM formulas is growing but still limited by Western clinical trial standards. These studies provide emerging evidence and should be considered alongside practitioner expertise.