Can Leeches Be Used as Medicine? A Detailed Explanation of Their Benefits and Effects

The leech, commonly known as the bloodworm, grows and reproduces in inland freshwater waters and is a traditional specialty medicinal aquatic animal in China. So can leeches be used as medicine? It is understood that they were already recorded in The Divine Farmer's Materia Medica, possess high medicinal value, and after their dried products are processed, they are used in traditional Chinese medicine to treat stroke, high blood pressure, blood stasis, amenorrhea, traumatic injuries, and other conditions.

Zhang Zhongjing's Dahuang Zhechong Wan uses leeches in combination with rhubarb, ground beetle, peach kernel, gadfly, and other medicines to treat five-taxation extreme deficiency and emaciation, dry blood binding internally, scaly skin, darkening of both eyes, and blocked menstruation in women. This formula is now used to treat cirrhosis and also has very good results. In Biejia Jian Wan, Didang Tang, and Didang Wan, the medicine leech is included in all of them to treat malarial masses and blood accumulation patterns. A careful examination of the patterns Zhongjing treated with leeches shows that most were blood stasis accumulating over time into masses or abdominal lumps that required slow resolution and gradual transformation, and they were mostly made into pill and powder formulations. Checking ancient literature, although the conditions treated by leeches were relatively broad, all state that it has the effects of breaking blood, expelling stasis, and unblocking menstruation, and is used for blood accumulation, abdominal lumps, accumulations, amenorrhea in women, dry blood turning into consumptive disease, traumatic injuries, red painful eyes, corneal opacities, and other conditions.

Harvesting and Processing

Capture in summer and autumn, scald to death with boiling water, then sun-dry or dry at low temperature.

Hang-dried leeches are generally pierced directly through with iron wire while the leech is alive, so hang-dried leeches generally have a small hole and an irregular shape. Leeches that are scalded to death and then sun-dried generally have a relatively smooth and straight appearance, with both sides slightly curled. Some scalded-to-death leeches, because they are not dried in time, will have a large number of anaerobic bacteria multiply inside the body, and after producing gas they swell, giving the appearance of a somewhat bulging belly. Accompanied by tissue cell necrosis and edema, their medicinal efficacy is much lower than that of hang-dried leeches.

For processed leeches, those that are naturally flat, well dried, with a level abdomen, brittle and easy to break, and with a gelatinous and glossy cross-section are considered the best.

Preparation

Leech: wash clean, cut into sections, and dry.

Scalded leech: take clean leech sections and, according to the scalding method, scald with talcum powder until slightly puffed.

The Benefits of Leech

Breaks blood and expels stasis, unblocks menstruation and dissolves masses. Mainly for blood stasis amenorrhea, abdominal masses and lumps, and traumatic injuries.

1. Treating acute conjunctivitis

Place 3 live bloodworms in 6 ml of raw honey, and after 6 hours store the infusion in a bottle for later use. Drop into the eyes once daily, 1 to 2 drops each time. In 380 treated cases, most of which were bilateral conjunctivitis, all were cured. The shortest cure time was 1 day, and the longest was 5 days. During treatment, apart from slight pain 1 to 2 minutes after eye drops, no adverse reactions were seen. It also has a certain effect on chronic conjunctivitis and pterygium. (The formula must be used under a doctor's guidance.)

2. For traumatic injuries

For internal injury and contusion with internal blood swelling and blood accumulation, leech can be filed into powder, or calcined (preserving its properties) into powder, then combined with notoginseng powder, musk, and the like, and taken with wine or warm boiled water, or soaked in wine for oral use.

3. For abdominal masses

It has been tried in anticancer agents, generally combined with other anticancer Chinese herbal medicines and made into pills, powders, or tablets for oral use. For example, it is combined with seaweed to make Leeches and Seaweed Powder to treat esophageal cancer, but the efficacy still awaits further observation.

4. Anti-thrombotic

Hirudin is effective for various thrombotic diseases, especially venous thrombosis and disseminated intravascular coagulation. Giving an appropriate amount of hirudin can inhibit the formation of carotid artery thrombosis in rats and rabbits, and the thrombi formed are smaller than those in the control group.

5. Restoring neurological function

Leech can promote the absorption of hematoma in experimental acute cerebral hemorrhage in rabbits, reduce inflammatory reaction and edema around brain tissue, relieve increased intracranial pressure, improve local circulation, and help the recovery of neurological function; it also promotes the absorption of experimental local hematoma in rabbit ears.

The Effects of Leech

1. Anticoagulant effect

Hirudin can block the action of thrombin on fibrin and hinder blood coagulation. Hirudin is not destroyed by heat or ethanol. Leeches can also secrete a histamine-like substance, thereby dilating capillaries and increasing bleeding. The blood coagulation-inhibiting effect of leech alcohol extract is stronger than that of gadfly, ground beetle, and peach kernel, and the effect of leech alcohol preparations is stronger than that of water preparations. 20 mg of hirudin can prevent the coagulation of 100 g of human blood.

Leech water extract can reduce whole blood specific viscosity and plasma specific viscosity in rats. It shortens erythrocyte electrophoresis time. Clinical studies show that leech has an improving effect on the thick, viscous, and aggregated state appearing in patients with ischemic cerebrovascular disease due to abnormal hemorheology.

2. Improving microcirculation

Intravenous injection of leech injection at 2 g/kg can promote the absorption of hematoma in experimental acute cerebral hemorrhage in rabbits, reduce inflammatory reaction and edema around brain tissue, relieve increased intracranial pressure, improve local circulation, and help the recovery of neurological function; it also promotes the absorption of experimental local hematoma in rabbit ears.

3. Anti-early pregnancy effect

Subcutaneous injection of 40% leech water decoction at 2.5 to 3.0 g/kg for 2 consecutive days has a pregnancy-terminating effect on mice at all stages of pregnancy, including implantation and early, middle, and late stages, but the effect is best on early pregnancy; if exogenous progesterone is injected simultaneously with leech, it can counteract the anti-early pregnancy effect of leech.

5. Effects on the cardiovascular system

Leech has the effects of dilating capillaries, improving microcirculation, and increasing renal blood flow. Its effect of improving microcirculation is similar to that of heparin, only its duration of action is short. Experiments show that leech has the effects of dilating peripheral blood vessels, increasing blood flow, and reducing vascular resistance, and this effect is similar to that of papaverine hydrochloride.

7. Other effects

Leech has a significant lowering effect on cholesterol and triglycerides in rabbits with experimental hyperlipidemia. Hirudin has an inhibitory effect on tumor cells and a certain inhibitory effect on the growth of liver cancer in mice. Because leeches have a strong anticoagulant effect, they are beneficial for anticancer drugs and immunologically active cells to penetrate cancer tissue and kill cancer cells.

Usage of Leech

Oral use: in pills or powders, 0.5 to 4 qian. -- Chinese Materia Medica Dictionary

External use: place on the affected area to suck; or use the infusion as drops. -- Chinese Materia Medica Dictionary

Oral use: 1.5 to 3 g. -- Chinese Pharmacopoeia

Oral use: decoct in soup, 3-9 g; or in pills or powders, 0.5-1.5 g each time, with a large dose of 3 g each time. -- Chinese Materia Medica

Supplementary Formulas for Leech

Note: The following formulas must be used under a doctor's guidance.

1. To treat women with difficult menstrual flow

It also treats men with fullness and urgency of the bladder and blood stasis. Thirty leeches (prepared), thirty gadflies (remove wings and legs, prepared), twenty peach kernels (remove skin and tips), three liang of rhubarb (soaked in wine). Grind the above four ingredients into powder, cook with five sheng of water to obtain three sheng, remove the residue, and take one sheng warm. (Didang Tang from Essential Prescriptions of the Golden Cabinet)

2. To treat blood stasis in the abdomen of women

Difficult menstruation, either stopping or coming, with fullness and urgency in the heart and abdomen. Three liang of peach kernels (soaked in water, remove skin, tips, and twin kernels, stir-fried with bran until slightly yellow), forty gadflies (stir-fried until slightly yellow, remove wings and legs), forty leeches (stir-fried until slightly yellow), three liang of Sichuan rhubarb (cut into pieces and slightly stir-fried). Grind the above medicines and sift into powder, mix with refined honey and pound over one hundred times, and make pills the size of parasol tree seeds. Take fifteen pills each time on an empty stomach with hot wine. (Taoren Wan from Formulas from the Benevolent Sage)

3. To treat menstrual blockage

For menstrual blockage or postpartum lochia, with pain in the umbilical and abdominal region. Four liang of prepared rehmannia, fifty each of gadflies (remove heads and wings, stir-fried), leeches (stir-fried yellow together with glutinous rice, remove the glutinous rice), and peach kernels (remove skin and tips). Grind the above into powder, make honey pills the size of parasol tree seeds. Take five or seven pills each time on an empty stomach with warm wine. (Dihuang Tongjing Wan from Good Formulas for Women)

4. To treat dripping discharge with unceasing bleeding

Sift leech, take about one qian with wine, twice a day, and when the bad blood dissolves, the illness is cured. (Prescriptions Worth a Thousand Gold)

5. To treat fractures

Dry leech on a new tile, make into fine powder, mix one qian with hot wine and take it; after about the time of a meal, the pain may ease, and after one more dose, the pain stops. Then apply fracture medicine and secure it with something to hold it in place. (Experiential Formulas)

6. To treat metal wounds and injuries

For metal wounds and injuries, falling from a height, being crushed by wood or stone, internal damage with blood stasis, heart and abdominal pain, inability to urinate or defecate, and near death from qi exhaustion. Half a liang of red leech (slowly stir-fried with lime until scorched yellow), two liang of rhubarb, two liang of black morning glory. Grind each of the above into fine powder. Take three qian each time, mix with hot wine and take; after about the time to walk four or five li, use hot wine again to mix two qian of morning glory powder to urge it on. The organs must discharge the bad blood, either in clumps or in pieces, and when the bad blood is fully discharged, the illness is cured. (Duoming San from Formulas for Succoring Life)

7. To treat bone injury, damage, and fracture pain

Equal parts of leech (stir-fried yellow with glutinous rice, remove the rice), white silk (burned to ash), myrrh (ground separately), and frankincense (ground separately), and fifteen tufts of human hair (a boy's small hair) (burned to ash). Grind the above into powder. Those over fifty take one qian, those under twenty take half a qian, and children take half a character; take with warm wine. (Jiegu Rushen San from Prescriptions for Universal Relief)

Story

The Gou Daoxing edition of In Search of the Supernatural from the Dunhuang caves records a story: during the Spring and Autumn and Warring States period, King Hui of Chu was dining with his ministers when there was a leech in the pickled vegetables. He had originally wanted to pick it out and throw it away, but fearing that the kitchen official would be punished because of it, he wrapped it in pickled cabbage and swallowed it. King Hui's cold illness, originally caused by cold pathogenic factors, was cured when he vomited after eating the leech.

Tao Hongjing, a physician of the Northern and Southern Dynasties, also recorded this story: “The King of Chu ate cold vegetables (that is, pickled cabbage) and, seeing a leech, swallowed it, and indeed it was able to remove accumulated masses; although there was hidden blessing, it was also the nature of things.” Similar records also appear in Jia Yi Xin Zhuan. Eastern Han Wang Chong's Lunheng explains: the leech is a blood-eating insect, and the King of Chu likely had a disease of accumulated blood, so eating a leech cured his illness.