I. Origins and History

1. Legendary Origins

The origins of Huaihua San are accompanied by some intriguing folklore. According to tradition, an ancient physician once chanced to observe that during the season when the Sophora tree was in bloom, certain people who had regular contact with the flowers — such as villagers who worked among groves of Sophora trees — appeared to experience a reduction in their symptoms of bloody stools. Through careful observation and study, this physician attempted to use the Sophora flower as a medicinal and combined it with other herbs, gradually giving rise to an early prototype of Huaihua San. Through continuous practice and refinement, the formula composition as it is known today was eventually established. This is of course a legend without definitive historical documentation, but it reflects the likelihood that the Sophora flower's potential in treating certain conditions had already captured the attention of ancient physicians.

2. Historical Development

Huaihua San was first recorded in the Song dynasty work Puji Benshifang (Prescriptions for Universal Relief). The text describes the formula as consisting of four herbs — Huaihua (Sophora Flower), Boye (Biota Leaves), Jingjie Sui (Schizonepeta Spike), and Zhike (Bitter Orange) — principally treating intestinal wind and visceral toxin with bloody stools. Thereafter, physicians of successive dynasties continued to apply and study the formula. During the Ming and Qing periods, clinical application of Huaihua San became increasingly widespread; physicians made various adjustments and refinements to dosages, processing methods, and combinations based on differing disease presentations and patient constitutions, further sharpening its clinical efficacy. With the advancement of medicine, Huaihua San spread not only throughout China but also to neighbouring countries, exerting a certain influence on medical development across East Asia.

3. Historical Clinical Cases

Ancient physicians have left behind numerous clinical records of Huaihua San in practice. For example, the Ming dynasty physician Zhang Sanxi documented a patient who had suffered from prolonged bloody stools with bright-red blood and a sensation of rectal bearing-down. Zhang Sanxi diagnosed the condition as intestinal wind with bloody stools and prescribed Huaihua San. After several doses, the bleeding markedly diminished and the bearing-down sensation gradually resolved. Similarly, the Qing dynasty physician Wu Jutong noted in his case records a middle-aged man who had developed bloody stools from dietary irregularity — the blood appeared in jet-like spurts and was dark purple in colour. Wu Jutong identified the pattern as visceral toxin with bloody stools and treated with a modified Huaihua San, with gradual improvement. These cases demonstrate the notable clinical efficacy of Huaihua San in classical medical practice.

II. Herb Composition (Sovereign, Minister, Assistant, Envoy)

1. Sovereign Herb: Huaihua (Sophora Flower)

Huaihua consists of the dried flowers and flower buds of Sophora japonica (Fabaceae). It is bitter in flavour and slightly cold in nature, entering the Liver and Large Intestine channels. Huaihua cools the blood and stops bleeding and is regarded as a key medicinal for treating downward-type bleeding conditions such as bloody stools and haemorrhoidal bleeding. Its designation as sovereign herb reflects its potent, targeted action: it acts directly on blood-heat in the lower burner to perform the critical function of cooling the blood and stopping bleeding. In Huaihua San, Huaihua is used in a relatively large proportion in order to emphasise its leading role in treating the primary presentation. Modern research has demonstrated that Huaihua contains flavonoid constituents such as rutin and quercetin, which possess anti-inflammatory and haemostatic effects, further confirming the herb's importance within the formula. Additionally, Huaihua clears the liver and drains fire, enabling both symptomatic and root treatment of bloody stools arising from excessive liver channel heat.

2. Minister Herb: Cebaiye (Biota Leaves)

Cebaiye consists of the dried branch tips and leaves of Platycladus orientalis (Cupressaceae). It is bitter and astringent in flavour, cold in nature, and enters the Lung, Liver, and Spleen channels. Cebaiye cools the blood and stops bleeding, and is used in mutual assistance with Huaihua to enhance the blood-cooling and haemostatic effect. It not only stops bleeding but also arrests bleeding through astriction, making it particularly effective for prolonged bloody stools and persistent haemorrhage. Cebaiye additionally clears the lung and stops coughing, providing supplementary benefit for patients with accompanying respiratory symptoms. Within Huaihua San, Cebaiye acts as minister herb, supporting the sovereign Huaihua and jointly reinforcing the blood-cooling and haemostatic action, making the formula's medicinal forces more synergistic and its therapeutic effect more pronounced. Cebaiye contains multiple flavonoid compounds with antioxidant and anti-inflammatory properties that contribute to its haemostatic and therapeutic activities.

3. Assistant Herb: Jingjie Sui (Schizonepeta Spike)

Jingjie Sui consists of the dried flower spikes of Schizonepeta tenuifolia (Lamiaceae). It is acrid in flavour and slightly warm in nature, entering the Lung and Liver channels. Within Huaihua San, Jingjie Sui performs the functions of dispersing wind and releasing the exterior, and venting wind-heat outward. On one hand, it disperses wind pathogen lodged in the body's surface layer, preventing wind from penetrating the blood aspect and worsening the bloody stool presentation; on the other hand, it vents heat out of the blood aspect, providing an exit route for the heat pathogen. This action assists in regulating the body's qi and blood circulation, ensuring smooth blood flow and thereby contributing to haemostasis. Jingjie Sui also harmonises the other herbs, moderating the overall medicinal nature of the formula and preventing it from becoming excessively cold or warm in a way that might compromise therapeutic results. Modern pharmacological research has found that Jingjie Sui possesses anti-inflammatory and anti-allergic properties, lending further support to its role in treating bloody stools associated with wind pathogen.

4. Envoy Herb: Zhike (Bitter Orange)

Zhike consists of the dried immature fruit of Citrus aurantium and its cultivated varieties (Rutaceae). It is bitter, acrid, and sour in flavour, slightly cold in nature, and enters the Spleen and Stomach channels. Within Huaihua San, Zhike principally moves qi, widens the middle, disperses accumulation, and guides out stagnation. It regulates intestinal qi dynamic, ensuring the free flow of bowel qi and preventing qi stagnation and blood stasis from aggravating the bloody stools. Zhike also amplifies the action of the other herbs, guiding them directly to the site of disease. In the treatment of bloody stools, Zhike's qi-moving action helps improve intestinal blood circulation, facilitating the absorption and utilisation of the haemostatic herbs and thus enhancing the therapeutic effect of the formula. Zhike contains volatile oils and flavonoids that regulate gastrointestinal function and promote digestive secretion, further illustrating its envoy role within the formula.

III. Pathomechanism, Actions, and Indications

1. Pathomechanism

The pathomechanism targeted by Huaihua San is principally wind-heat and damp-toxin obstructing and accumulating in the blood aspect of the intestines. When wind-heat pathogen invades the body and penetrates the blood aspect, it scorches the vessels, causing blood to extravasate and bleed. Damp-toxin accumulating in the intestines disrupts qi and blood circulation, also giving rise to bloody stools. Furthermore, prolonged dietary irregularity and emotional disturbance can impair spleen-stomach function, generating damp-heat internally and worsening the condition. With intestinal qi and blood flowing poorly and blood movement becoming abnormal, symptoms arise including bloody stools with bright-red or dark-purple blood. Concurrently, due to the presence of wind-heat damp-toxin, rectal bearing-down, pain, and itching may also accompany the presentation.

2. Actions

Huaihua San clears the intestines and cools the blood, and disperses wind while moving qi. Clearing the intestines and cooling the blood addresses the heat pathogen in the intestinal blood aspect and the haemorrhagic symptoms: through the blood-cooling and haemostatic actions of Huaihua and Cebaiye, heat in the intestinal blood aspect is cleared and bleeding is arrested. Dispersing wind and moving qi utilises the exterior-releasing action of Jingjie Sui and the qi-moving, middle-widening action of Zhike to dispel wind pathogen and regulate intestinal qi dynamic, ensuring smooth qi and blood flow and preventing qi stagnation and blood stasis from compounding the condition. These two actions work in concert to address both root and branch: bleeding symptoms are rapidly relieved while the body's qi and blood movement is rebalanced, preventing recurrence.

3. Indications

Huaihua San principally treats intestinal wind (chang feng) and visceral toxin (zang du) with bloody stools. Intestinal wind with bloody stools is characterised by bright-red blood, dripping or appearing in jet-like spurts, most often occurring before defecation, and accompanied by anal itching. Visceral toxin with bloody stools presents as dark-purple blood, sometimes with mucus, most often occurring after defecation, with accompanying rectal bearing-down and discomfort. Huaihua San also yields good therapeutic results for haemorrhoidal bleeding and anal fissure bleeding where the pattern is wind-heat and damp-toxin obstructing the intestinal blood aspect. Clinically, any patient whose presentation matches the above pathomechanism and symptom profile may be treated with Huaihua San.

IV. Formula Analysis

1. Compositional Rationale for Cooling Blood and Stopping Bleeding

Huaihua and Cebaiye are both blood-cooling and haemostatic medicinals; used together, they reinforce the blood-cooling and haemostatic effect. Huaihua enters specifically the Large Intestine channel and excels at clearing large intestine blood-heat, with a specific action on intestinal bleeding. Cebaiye both cools and stops bleeding through astriction, yielding good results across various haemorrhagic patterns. Used in mutual assistance, the two herbs act directly on the heat pathogen in the intestinal blood aspect and the haemorrhagic presentation. Through cooling the blood, heat is cleared, the vessels are restored, and bleeding is thereby arrested.

2. Synergistic Action of Wind-Dispersing and Qi-Moving Herbs

The exterior-releasing and wind-dispersing action of Jingjie Sui and the qi-moving and middle-widening action of Zhike operate in mutual synergy. Jingjie Sui disperses wind pathogen lodged in the body's surface, preventing wind from penetrating the blood aspect, while simultaneously venting heat outward from the blood aspect. Zhike regulates intestinal qi dynamic, ensuring the free flow of bowel qi and preventing qi stagnation and blood stasis. Together, they dispel wind pathogen to eliminate the exogenous contributing factor in the bloody stool presentation, while also regulating intestinal qi and blood, improving intestinal blood circulation, facilitating the absorption and utilisation of the haemostatic herbs, and enhancing the blood-cooling and haemostatic effect.

3. Overall Compositional Strengths

The overall compositional strength of Huaihua San lies in the coordinated interplay of all four herbs — sovereign, minister, assistant, and envoy — each fulfilling its designated role. The sovereign Huaihua leads the blood-cooling and haemostatic action; the minister Cebaiye assists and amplifies the medicinal force; the assistant Jingjie Sui disperses wind pathogen and vents blood-heat; and the envoy Zhike moves qi, widens the middle, and guides the other herbs to the site of disease. Acting in concert, the four herbs address both the heat pathogen in the intestinal blood aspect and the haemorrhagic presentation, while simultaneously attending to the body's overall qi and blood circulation and the elimination of external pathogenic factors — thereby giving the formula its comprehensive effects of clearing the intestines, cooling the blood, dispersing wind, and moving qi, effectively treating intestinal wind and visceral toxin with bloody stools through both root and branch.

V. Comparison with Related Formulas

1. Comparison with Huangtu Tang

Huangtu Tang is also a classical formula for treating bloody stools, composed of Gancao (Licorice Root), Gan Dihuang (Dried Rehmannia Root), Baizhu (Atractylodes Rhizome), Fuzi (Aconite), Ejiao (Ass-hide Gelatin), Huangqin (Scutellaria Root), and Zaoxin Huangtu (Hearth Earth). Huangtu Tang focuses on treating bloody stools due to spleen-stomach deficiency-cold and the spleen's failure to contain the blood, with herbs centred on warming and tonifying the spleen-stomach, supplemented by blood-cooling and haemostatic agents. By contrast, Huaihua San primarily targets bloody stools caused by wind-heat and damp-toxin obstructing the intestinal blood aspect, with clearing the intestines, cooling the blood, dispersing wind, and moving qi as its principal therapeutic functions. The two formulas differ substantially in pathomechanism, herb composition, and clinical actions. Huangtu Tang is suited to deficiency-cold type bloody stools, where patients typically present with a sallow complexion, fatigue, and cold aversion with cold limbs; Huaihua San is suited to heat-type bloody stools, where patients typically present with rectal bearing-down, pain, and itching, with blood that is bright red or dark purple.

2. Comparison with Shi Hui San

Shi Hui San is composed of Daji (Japanese Thistle), Xiaoji (Field Thistle), Heye (Lotus Leaf), Cebaiye (Biota Leaves), Maogen (Imperata Root), Qiangen (Madder Root), Shanzhi (Gardenia Fruit), Dahuang (Rhubarb Root), Mudanpi (Tree Peony Bark), and Zonglv Pi (Palm Bark). It clears the blood and stops bleeding and is principally used to treat various haemorrhagic conditions arising from blood-heat running recklessly. Compared with Huaihua San, Shi Hui San is more forceful and drastic in action, with a primary emphasis on cooling blood and stopping bleeding; it is well-suited to haemorrhagic conditions where bleeding is substantial and the clinical presentation is acute. Huaihua San, by comparison, is relatively moderate in character — not only cooling the blood and stopping bleeding, but also dispersing wind and moving qi, making it more appropriate for patients with intestinal bleeding accompanied by wind-heat or qi stagnation. Shi Hui San is most commonly used for upper-body bleeding such as haemoptysis and epistaxis, whereas Huaihua San is principally indicated for lower-body bleeding such as bloody stools.

VI. Clinical Applications

1. Internal Haemorrhoidal Bleeding

Internal haemorrhoidal bleeding is a commonly encountered clinical condition, typically presenting as bright-red blood in the stool that drips or appears in jet-like spurts, and may be accompanied by prolapse of haemorrhoidal tissue and pain. For internal haemorrhoidal bleeding where the pattern is wind-heat and damp-toxin obstructing the intestinal blood aspect, Huaihua San yields good therapeutic results. By clearing the intestines, cooling the blood, dispersing wind, and moving qi, it alleviates haemorrhagic symptoms, reduces haemorrhoidal prolapse and pain, and supports the recovery of internal haemorrhoids. In clinical application, dosage and herb combinations may be adjusted according to the patient's specific presentation.

2. Anal Fissure Bleeding

Anal fissure bleeding most often occurs when dry, bound stools require excessive straining at defecation, causing rupture of the anal canal skin with bright-red bleeding and severe pain — particularly intensifying after bowel movements. Huaihua San has a beneficial therapeutic role in anal fissure bleeding: its effects of clearing the intestines, cooling the blood, dispersing wind, and moving qi help to dissipate intestinal heat, reduce local inflammation at the fissure, promote healing of the fissure wound, and decrease bleeding. The herbs in the formula also improve local anorectal blood circulation and relieve pain. In treating anal fissure bleeding, the formula may be combined with external sitz bath therapy to enhance the therapeutic effect.

3. Ulcerative Colitis with Bloody Stools

Patients with ulcerative colitis frequently experience bloody stools, often accompanied by abdominal pain, diarrhoea, and mucous-purulent bloody stool. Huaihua San also has clinical value in this setting. It clears the intestines and cools the blood, alleviating intestinal inflammation and reducing bleeding. Simultaneously, by dispersing wind and moving qi, it improves disordered intestinal qi dynamic and reduces abdominal pain and diarrhoea. In clinical application, the formula may be combined with other medications for ulcerative colitis according to the patient's specific condition to achieve better outcomes.

VII. Clinical Modifications

1. Profuse Bleeding

When bleeding is profuse, Diyu (Sanguisorba Root) and Xianhechao (Agrimony) may be added to strengthen the haemostatic effect. Diyu cools the blood and stops bleeding, and resolves toxicity and constrains sores; it yields good results across various haemorrhagic conditions and excels particularly in treating blood-heat bleeding in the lower burner. Xianhechao astringes bleeding and tonifies and strengthens the body; for patients with significant blood loss leading to qi and blood deficiency, it both arrests bleeding and supports the body's upright qi. Combined with Huaihua San, these two herbs enhance the formula's haemostatic effect and effectively control haemorrhagic symptoms.

2. Accompanying Abdominal Pain

Where abdominal pain is pronounced, Baishao (White Peony Root) and Muxiang (Costus Root) may be added to relax tension and relieve pain. Baishao nourishes the blood, astringes yin, softens the liver, and relieves pain; it relaxes intestinal spasm and alleviates abdominal pain. Muxiang moves qi, relieves pain, strengthens the spleen, and promotes digestion; it enhances the free flow of intestinal qi dynamic and alleviates abdominal pain. Added to Huaihua San, these two herbs specifically address the abdominal pain presentation and improve patient comfort.

3. Pronounced Damp-Heat

Where damp-heat is pronounced, Huanglian (Coptis Rhizome) and Huangbo (Phellodendron Bark) may be added to clear heat and dry dampness. Both Huanglian and Huangbo are heat-clearing and dampness-drying medicinals with the actions of clearing heat, drying dampness, draining fire, and resolving toxicity. They amplify Huaihua San's capacity to clear and drain damp-heat, effectively eliminating damp-heat pathogen in patients with more severe intestinal damp-heat and improving the clinical condition. In practice, the dosages of Huanglian and Huangbo may be adjusted according to the severity of the damp-heat.

VIII. Dosage and Preparation

1. Traditional Powder Method

2. Modern Concentrated Granules

Modern concentrated granules are a contemporary Chinese herbal dosage form. Huaihua, Cebaiye, Jingjie Sui, and Zhike are extracted, concentrated, and dried according to the traditional formula proportions to produce a granule preparation. The typical dose is 1–2 sachets per administration, dissolved in hot water and taken 2–3 times daily. Modern concentrated granules offer the advantages of convenient administration, accurate dosing, and ease of storage. They retain the active constituents of the traditional herbs while overcoming the inconvenience of classical decoctions, making them well-suited to contemporary lifestyles. Patients need only dissolve them in hot water without the laborious decoction process, greatly improving patient adherence.

IX. Precautions and Contraindications

1. Dietary Restrictions

While taking Huaihua San, spicy, greasy, and irritating foods should be avoided. Such foods readily generate heat and fan fire, aggravating damp-heat pathogen in the intestines and impeding recovery. Foods to avoid include chilli peppers, Sichuan peppercorns, and deep-fried items. Tobacco and alcohol should also be abstained from, as they are irritating in nature and may reduce the efficacy of the formula or even worsen bloody stool symptoms.

2. Constitutional Differences

Huaihua San should be used with caution in individuals with a cold-deficient constitution. As the formula's overall medicinal nature tends towards cold and cooling, those with a cold-deficient constitution may experience aggravation of internal cold-deficiency symptoms upon taking it, leading to abdominal pain, diarrhoea, and other adverse effects. Such patients should consult a physician before use and select an appropriate treatment based on their individual circumstances. Additionally, pregnant women should use Huaihua San with caution; while the herbs in the formula generally carry no marked teratogenic risk, pregnant women should nonetheless seek the advice of a qualified physician before use to ensure foetal safety.

3. Monitoring the Clinical Condition

While taking Huaihua San, patients should closely monitor any changes in their condition. If haemorrhagic symptoms fail to improve or worsen, medical attention should be sought promptly and the treatment plan adjusted accordingly. Patients should also observe whether other discomforts emerge — such as fever or intensified abdominal pain — so that any notable changes in the clinical condition can be identified and addressed in a timely manner.

X. Modern Research

1. Pharmacological Research

Huaihua San is a classical formula for clearing the intestines and stopping bleeding, possessing the ability to clear damp-heat from the large intestine, and principally treating bloody stools and haemorrhoidal bleeding arising from large intestine damp-heat.

Modern pharmacological research has demonstrated that Huaihua contains flavonoid constituents such as rutin and quercetin, which possess anti-inflammatory, antioxidant, capillary-stabilising, and haemostatic effects; the flavonoids in Cebaiye also exhibit haemostatic, astringent, and anti-inflammatory activities; Jingjie Sui contains volatile oil constituents with anti-inflammatory, anti-allergic, and immune-regulating properties; and Zhike contains volatile oils and bitter principles that promote gastrointestinal motility and regulate intestinal qi dynamic. Taken together, Huaihua San exerts its haemostatic and healing effects through multiple synergistic mechanisms — including anti-inflammation, astriction, vascular stabilisation, and intestinal function regulation.

2. Clinical Research and Efficacy Observations

Multiple clinical observations and small-sample trials have shown that Huaihua San and its modified variants, when used for internal haemorrhoidal bleeding, anal fissure bleeding, and ulcerative colitis with bloody stools, can shorten the time to haemostasis, reduce the frequency of bloody bowel movements, and improve anorectal discomfort, with a low incidence of adverse reactions. Some randomised controlled trials comparing Huaihua San with conventional Western pharmaceuticals or other Chinese herbal formulas have demonstrated comparable or complementary efficacy in reducing bleeding and relieving symptoms; however, further large-sample, multicentre randomised controlled trials are still needed to more definitively establish efficacy and safety.

3. Advances in Dosage Form and Delivery Technology

To improve convenience and stability, Huaihua San has been developed into multiple dosage forms including concentrated granules, capsules, tablets, and topical preparations (sitz bath solutions and suppositories). Modern pharmaceutical technologies — including extraction and purification, micronisation, and encapsulated delivery systems — help to improve the bioavailability of active constituents, reduce gastrointestinal irritation, and facilitate broader clinical use.

4. Safety Assessment and Adverse Event Monitoring

Overall observations suggest that Huaihua San is generally well tolerated; however, owing to its cold and cooling nature, patients with spleen-stomach deficiency-cold may experience induced diarrhoea or abdominal pain. Caution and close monitoring of haemorrhagic parameters are required when used concurrently with anticoagulant medications such as warfarin. The formula is contraindicated in patients with known hypersensitivity to its constituents. Drug interactions and long-term safety require further follow-up and systematic evaluation.

5. Future Research Directions

Future research priorities are suggested as follows: large-sample, multicentre randomised controlled clinical trials to confirm efficacy; constituent-based target identification and metabolic pathway studies to elucidate molecular mechanisms; optimisation of dosage forms and administration protocols to improve bioavailability and patient adherence; and the establishment of standardised clinical pathways and safety monitoring frameworks to promote the regulated application of Huaihua San within the modern medical context.