Herb

Shui Zhi

Leech (processed) | 水蛭

Also known as:

Hirudo

Shui Zhi

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Properties

Blood-invigorating and stasis-dispelling herbs (活血化瘀药) · Neutral

Traditionally supports*

Cardiovascular Health Menstrual Health Stroke Recovery Injury and Trauma Recovery

Parts Used

Animal — whole (全虫 quán chóng)

*These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.

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About This Herb

Traditional Chinese Medicine background and properties

Herb Description

Shuǐ Zhì (leech) is one of the most powerful Blood stasis-breaking substances in Chinese medicine, used when stubborn, long-standing Blood stagnation resists milder herbs. It is primarily used for conditions involving fixed abdominal masses, absent menstruation due to Blood clots, traumatic injuries with internal bruising, and the aftermath of stroke. Despite its strong action, classical texts note it breaks up old stagnant Blood without harming healthy new Blood.

Herb Category

Blood-invigorating and stasis-dispelling herbs (活血化瘀药) Blood-breaking and mass-dispersing herbs (破血消癥药)

Main Actions

  • Breaks Blood and Dispels Stasis
  • Promotes Menstruation
  • Disperses Accumulations and Dissipates Nodules

How These Actions Work

'Breaks Blood and expels stasis' means Shuǐ Zhì powerfully disperses old, stubborn Blood stagnation that has been stuck in the body for a long time. Unlike milder Blood-moving herbs such as Peach Kernel or Safflower, Shuǐ Zhì targets deeply lodged, hardened clots of stagnant Blood that resist gentler treatment. Its salty taste allows it to penetrate into the Blood level, while its bitter taste helps it push downward and break through blockages. Classically, this is expressed as 'salty enters the Blood, bitter purges stagnation' (咸入血走血，苦泄结). A key classical observation is that Shuǐ Zhì breaks up old stagnant Blood without damaging fresh, healthy Blood. This makes it especially valuable for long-standing Blood stasis conditions.

'Unblocks the channels and promotes menstruation' means it restores menstrual flow that has been blocked by Blood stasis. When stagnant Blood obstructs the uterine vessels and the Chōng and Rèn meridians, menstruation stops. Shuǐ Zhì's powerful stasis-breaking action clears these obstructions so that normal menstrual flow can resume. This is one of its most ancient recorded uses, dating back to the Shén Nóng Běn Cǎo Jīng.

'Disperses masses and accumulations' refers to its ability to break down fixed abdominal masses (癥瘕 zhēng jiǎ) caused by chronic Blood stasis. In TCM, when stagnant Blood accumulates over time, it can solidify into palpable lumps in the abdomen. Shuǐ Zhì, as an animal-derived substance with a natural affinity for blood, gradually penetrates and dissolves these hardened masses. It enters the Liver channel, which governs Blood storage and the smooth flow of Qi, making it particularly effective at addressing stasis in the Blood level of the Liver system.

Patterns Addressed

In TCM, symptoms cluster into recognizable patterns of disharmony that reveal what's out of balance in the body. Shui Zhi is traditionally associated with these specific patterns.

The following describes this herb's classification within Traditional Chinese Medicine theory and is provided for educational purposes only.

Why Shui Zhi addresses this pattern

Shuǐ Zhì directly targets the core pathomechanism of Blood Stasis. Its salty taste penetrates the Blood level and its bitter taste drives downward to break through obstructions. Entering the Liver channel (which governs Blood storage and smooth flow), it powerfully breaks up stagnant Blood that has become fixed and hardened. As a blood-feeding animal, it has what classical texts call a natural 'affinity' for stagnant Blood, seeking it out and dissolving it gradually without injuring fresh Blood. This makes it especially suited for severe or chronic Blood Stasis where lighter herbs like Peach Kernel or Safflower have been insufficient.

A practitioner would look for one or more of these signs

Amenorrhea

Menstrual absence due to Blood stasis obstruction

Abdominal Pain

Fixed, stabbing lower abdominal pain that worsens with pressure

Dark Menstrual Clots

Dark clotted menstrual blood when flow does occur

Pale Tongue

Purple or dark tongue with stasis spots

TCM Properties

Temperature

Neutral

Taste

Salty (咸 xián), Bitter (苦 kǔ)

Channels Entered
Liver Urinary Bladder
Parts Used

Animal — whole (全虫 quán chóng)

This is partial information on the herb's TCM properties. More detailed information is available on the herb's dedicated page

Product Details

Manufacturing, supplier, and product specifications

Product Type

Granules

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Botanical & Sourcing

Quality Indicators

For the broad-bodied leech (蚂蟥, Whitmania pigra, the most commonly used species): good quality specimens are flat and spindle-shaped, 4–10 cm long, with a dark brown-black back showing 5 faint longitudinal stripes when soaked, and a flat yellowish-brown belly. The texture should be brittle and easy to snap, with a shiny, gelatinous cross-section. The smell should be faintly fishy but not putrid. For the Japanese medicinal leech (水蛭, Hirudo nipponica): good quality pieces are small (2–5 cm), cylindrical, dark brown-black throughout, often twisted and strung together. They should snap cleanly with an uneven, non-glossy fracture surface. Processed (talcum-fried) Shui Zhi should appear slightly puffed, yellowish-brown, crisp, and easy to powder. Avoid specimens that are damp, moldy, have excessive earthy smell, or show signs of insect damage. In Sichuan, a variety with distinct yellow-green striping called 'gold-edge leech' (金边蚂蟥) is considered especially high quality.

Primary Growing Regions

Shui Zhi is distributed widely across China in freshwater environments. The main producing regions include Shandong (especially around Weishan Lake), Jiangsu (around Taihu Lake), Anhui (Huaiyuan area), and Hubei (around Honghu Lake). Historically, the area around Weishan Lake in Shandong and Baiyangdian in Hebei were among the largest production bases. Due to declining wild populations from habitat loss and pesticide use, large-scale aquaculture farms now supply much of the commercial demand, with major cultivation operations in Shandong, Jiangsu, Anhui, Hubei, and Zhejiang provinces.

Harvesting Season

Summer and autumn. Leeches are collected from freshwater habitats (ponds, paddy fields, lakes), then killed in boiling water and dried in the sun or at low temperature.

Supplier Information

Treasure of the East

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Miscellaneous Info

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Usage & Safety

How to use this herb and important safety information

Important Medical Disclaimer

The information provided here is for educational purposes only and is not intended as medical advice or to replace consultation with a qualified healthcare professional. This herb is a dietary supplement and has not been evaluated by the FDA. It is not intended to diagnose, treat, cure, or prevent any disease.

Always consult with a qualified healthcare provider, particularly if you are pregnant, nursing, have a medical condition, or are taking other medications. Discontinue use and consult your healthcare provider if you experience any adverse reactions.

Recommended Dosage

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Instructions for safe storage and consumption

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Traditional Dosage Reference

Standard

1–3g (powder/capsule); 3–6g (decoction)

Maximum

Up to 6g in decoction or 3g as powder for severe Blood stasis conditions. Reported toxic dose is 15–30g; do not exceed standard doses without expert supervision.

Notes

Shui Zhi is most commonly used as a ground powder in capsules or pills (1–3g per day) rather than in decoctions, because the key bioactive compound hirudin is a protein that is partially destroyed by prolonged boiling. Research suggests that unprocessed ground powder has higher fibrinolytic and anticoagulant activity than the talcum-fried processed form, though the latter is more traditional and easier to take due to reduced fishy smell. For decoctions: 3–6g, typically combined with other Blood-moving herbs (Tao Ren, Da Huang) as in Di Dang Tang. For powder/capsules: 1–1.5g per dose, 2–3 times daily, is the standard range. Lower doses (1–2g powder) are used for chronic cardiovascular conditions like coronary artery disease or post-stroke rehabilitation. Higher doses (up to 3g powder or 6g decoction) are reserved for acute Blood stasis conditions with clearly palpable masses, severe amenorrhea, or acute traumatic injury. Zhang Xichun in Yi Xue Zhong Zhong Can Xi Lu advocated using raw (unprocessed) Shui Zhi powder at approximately 1.5g doses for stubborn masses, finding it more effective than the fried form.

Processing Methods

Processing method

Clean Shuǐ Zhì segments are stir-fried with talcum powder (滑石粉) using the 'scalding method' (烫法) until they slightly puff up and become crisp.

How it changes properties

The thermal nature remains neutral. Scalding with talcum powder reduces the fishy smell, makes the material easier to grind into powder, and is believed to reduce the slight toxicity. The Blood-breaking action is somewhat moderated compared to the raw form, making it safer for oral use in decoctions and pills.

When to use this form

This is the standard processed form used in most clinical prescriptions today, as specified in the Chinese Pharmacopoeia. It is preferred for internal use in decoctions, pills, and powders because it is safer and easier to handle than the raw form.

Toxicity Classification

Slightly toxic

The 2020 Chinese Pharmacopoeia classifies Shui Zhi as having 'slight toxicity' (有小毒). Historical texts varied: the Shen Nong Ben Cao Jing did not mention toxicity, the Ming Yi Bie Lu stated 'toxic,' and the Ben Cao Gang Mu stated 'slightly toxic.' The primary bioactive and potentially toxic components are hirudin (a potent direct thrombin inhibitor), heparin-like substances, and anti-thrombotic proteins. Overdose (reported toxic dose: 15–30g) can cause nausea, vomiting, bleeding gums, nosebleeds, subcutaneous bruising, excessive menstrual bleeding, hematuria, and in severe cases gastrointestinal hemorrhage, severe abdominal pain, and intracranial bleeding. Proper processing (炮制) significantly reduces these risks. The standard method is to stir-fry with talcum powder (滑石粉烫) until the leech segments puff up slightly and turn yellowish-brown, which reduces the potency of heat-labile proteins like hirudin while making the material brittle and easier to grind for pills and powders. At standard clinical doses (1–3g as powder, 3–6g in decoction), Shui Zhi has extremely low clinical toxicity. Modern research confirms that properly processed Shui Zhi at therapeutic doses is safe, though long-term use requires monitoring for allergic reactions and bleeding tendency.

Contraindications

Avoid

Pregnancy. Shui Zhi is a powerful Blood-breaking herb that can stimulate uterine contractions and cause miscarriage. It is classified as a pregnancy-prohibited (禁用) substance in Chinese medical texts.

Avoid

Active bleeding or hemorrhagic conditions (e.g. hemorrhagic stroke, active gastrointestinal bleeding, hemophilia). Shui Zhi's potent anticoagulant properties can worsen uncontrolled bleeding.

Avoid

Absence of Blood stasis. Classical texts state that Shui Zhi is prohibited for those without genuine Blood stasis (无瘀血者禁用). Using it in patients with Qi or Blood deficiency alone, without stasis, risks depleting already weakened Blood.

Avoid

Menorrhagia or heavy menstrual bleeding. The Blood-breaking action can significantly worsen excessive menstrual flow.

Caution

Patients with severe thrombocytopenia or other coagulopathy disorders, where further impairment of clotting could be dangerous.

Caution

Patients with constitutional Qi and Blood deficiency who are frail and debilitated. Use with extreme caution, and only if Blood stasis is clearly present alongside the deficiency. Combine with tonifying herbs.

Caution

Perioperative period. Discontinue well before elective surgery due to its anticoagulant effects, which may increase surgical bleeding risk.

Caution

Patients with peptic ulcer disease or history of gastrointestinal bleeding. The anticoagulant activity may increase gastrointestinal bleeding risk.

Special Populations

Pregnancy

Absolutely contraindicated in pregnancy. Shui Zhi is classified as a pregnancy-prohibited (禁用) herb in Chinese medicine, alongside other powerful Blood-breaking substances like San Leng, E Zhu, and Meng Chong. Its potent Blood-breaking and stasis-dispelling action can directly stimulate uterine activity and provoke miscarriage. The active compound hirudin is a powerful thrombin inhibitor that could theoretically cross the placenta and affect fetal coagulation. Research on recombinant hirudin confirms it is not recommended in pregnancy due to transplacental passage. There are no circumstances where Shui Zhi should be used during pregnancy unless specifically required for termination under professional medical supervision.

Breastfeeding

There is no established safety data for Shui Zhi during breastfeeding. Given that its bioactive compounds (hirudin, heparin-like substances) are proteins and polypeptides, some transfer into breast milk is possible. Its strong Blood-breaking action could theoretically affect the nursing infant's developing coagulation system. It is generally considered inadvisable during breastfeeding unless the clinical need is urgent and the mother is under close practitioner supervision. If used, the infant should be monitored for signs of unusual bruising or bleeding.

Pediatric Use

Shui Zhi is generally not used in pediatric practice due to its potent Blood-breaking properties and slight toxicity. Children's Qi and Blood are considered immature and easily damaged by such strong-acting substances. If absolutely necessary for a confirmed Blood stasis condition in older children (typically over 10 years), the dosage should be reduced to roughly one-third to one-half of the adult dose, used only for short courses, and prescribed by an experienced practitioner. It should be avoided entirely in infants and young children.

Drug Interactions

Anticoagulant drugs (warfarin, heparin, enoxaparin, dabigatran, rivaroxaban, apixaban): Shui Zhi contains hirudin, a potent natural direct thrombin inhibitor, along with heparin-like substances. Concurrent use with pharmaceutical anticoagulants creates a significant risk of synergistic anticoagulation, leading to excessive bleeding. INR monitoring is essential if any combination is necessary, though concurrent use is generally inadvisable.

Antiplatelet drugs (aspirin, clopidogrel, dipyridamole, ticagrelor): Shui Zhi has demonstrated antiplatelet effects in animal studies, including inhibition of ADP-induced platelet aggregation. Combined use with antiplatelet medications may increase bleeding risk through additive or synergistic mechanisms.

Thrombolytic drugs (streptokinase, alteplase, tenecteplase): The combination of Shui Zhi's natural thrombin inhibition with pharmaceutical thrombolysis poses a high risk of hemorrhagic complications and should be avoided.

NSAIDs (ibuprofen, naproxen, diclofenac): NSAIDs impair platelet function and can cause gastrointestinal mucosal damage. Combined with Shui Zhi's anticoagulant effects, there is an increased risk of gastrointestinal bleeding.

Dietary Advice

Avoid cold, raw foods and iced drinks while taking Shui Zhi, as these can impede Blood circulation and work against the herb's stasis-breaking action. Avoid excessive consumption of foods that strongly promote Blood movement (such as large quantities of alcohol or very spicy foods) during treatment, as this may compound the anticoagulant effect and increase bleeding risk. A balanced diet that gently supports Blood circulation, including moderate amounts of warming, nourishing foods, is appropriate.

Cautions & Warnings

Although this herb is typically safe for most individuals, it may cause side effects in some people. Pregnant women, nursing mothers, postpartum women, and those with liver disease should use the formula with caution.

As with any Chinese herbal remedy, it is advisable to seek guidance from a qualified TCM practitioner before beginning treatment.