Eucommiae Cortex
Aliases：Si Xian, Si Zhong, Mu Mian, Mian, Shi Si Xian, Che Si Pi, Si Lian Pi, Si Mian Pi, Yu Si Pi
Du Zhong (Eucommiae Cortex), a Chinese medicinal, is a yang‑tonifying herb. It is the bark of Eucommia ulmoides Oliv., a plant of the Eucommiaceae family (genus Eucommia). The bark is flat and plate‑like, with a pale grayish‑brown outer surface and a reddish‑purple or purplish‑brown inner surface. Its most distinctive feature is that when broken, the fracture surfaces are connected by fine, silvery‑white, elastic rubbery threads that can be stretched to over 1 cm before breaking. For this reason, it is also known as “Che Si Pi” (Thread‑pulling bark).
Efficacy & Actions
Tonify the liver and kidney, strengthen the sinews and bones, and calm the fetus.
Indications
Liver‑kidney deficiency, soreness and weakness of the lower back and knees, weakness of the sinews and bones, dizziness and vertigo, gestational bleeding, and restless fetus (threatened miscarriage).
Modern Pharmacology
Antihypertensive (blood pressure lowering): Stir‑fried Du Zhong has twice the antihypertensive effect of raw Du Zhong. A water decoction is more potent than an alcohol extract. It is an important adjunctive agent for the prevention and treatment of hypertension. Du Zhong tea and other medicated diets are widely used for liver‑kidney deficiency presenting as dizziness, headache, and hypertension. Hypolipidemic and hypoglycemic: Flavonoid components lower serum cholesterol and triglycerides and help regulate blood glucose levels. The high content of α‑linolenic acid in Du Zhong seed oil is an important material basis for its lipid‑lowering effect. Strengthening sinews and bones, anti‑osteoporosis: Du Zhong maintains bone homeostasis by regulating bone angiogenesis and modulating the bone immune microenvironment. It has therapeutic effects on osteoporosis, lumbar disc herniation, etc., providing experimental evidence for its clinical use as an essential herb for low back pain. Calming the fetus and regulating reproductive function: Du Zhong exhibits sex hormone‑like effects. It is used for gestational bleeding and restless fetus (threatened miscarriage) due to kidney deficiency with insecurity of the fetal origin. According to TCM theory, it stabilizes the Chong and Ren meridians, nourishes the liver and kidney, and thus protects the fetus. Anti‑inflammatory, analgesic, and antioxidant: Various active components (e.g., iridoids, flavonoids) exert anti‑inflammatory, antioxidant, and analgesic effects by scavenging free radicals and inhibiting inflammatory pathways. Immunomodulatory (enhancing immunity) and anti‑fatigue: Du Zhong polysaccharides and other components improve immune function, enhance endurance, and delay aging. Neuroprotective, hepatoprotective, and renoprotective: Iridoid components protect nerves, the liver, and the kidneys, reducing damage. Both Du Zhong leaves and bark have been shown to possess hepatoprotective and renoprotective effects.
Ingredients
Phenylpropanoids: Approximately 50 compounds including chlorogenic acid. Exhibits antibacterial, anti‑inflammatory, antiviral, cardio‑cerebrovascular protective effects, and inhibits the occurrence of liver and colorectal cancer. Iridoids: 59 compounds including geniposide and aucubin. Prevents osteoporosis, possesses antibacterial, antiviral, hepatoprotective, renal protective, and antioxidant activities. Flavonoids: About 22 total flavonoids. Lowers blood pressure, blood sugar, and blood lipids; antioxidant activity; serves as an important quality marker for the herb. Phenolic acids: 14 phenolic acids. Exhibit antioxidant, anti‑inflammatory, and antitumor effects. Others: Polysaccharides, amino acids, eucommia rubber, vitamin C, and various trace elements. Enhance immunity, supplement nutrition, and regulate bone metabolism.
Usage & Dosage
Oral Administration Decoction: 6–15 g per dose. Generally 6–10 g in decoction; up to 15 g for treating low back pain or preventing miscarriage. Formulations: Can be made into pills, powder, or soaked in wine. Processed Forms Raw Eucommia (Sheng Du Zhong): Benefits the liver and relaxes sinews. Used for wind‑dampness arthralgia and damp eczema of the genitals. Salt‑processed Eucommia (Yan Du Zhong / Chao Du Zhong): Stir‑frying with salt breaks down the gum, improving extraction of active components and enhancing antihypertensive effect. It acts strongly on the kidney, often used for kidney‑deficiency low back pain, impotence, spermatorrhea, threatened miscarriage, and hypertension. Charred Eucommia (Du Zhong Tan): Enhances hemostatic effect, often used for metrorrhagia and metrostaxis. Other Uses A single decoction of Eucommia can be used to prevent miscarriage, or it can be combined with other herbs to tonify the kidney and strengthen the lower back.
Contraindications
I. Contraindications Contraindicated in yin deficiency with fire hyperactivity (dry mouth and throat, feverish sensation in palms, soles and chest, night sweats, red tongue with little coating) Contraindicated in patients with hypotension Contraindicated in cases of external febrile disease, exuberant internal heat, blood deficiency with blood heat, and Yangming fu-organ excess pattern Not suitable for long-term or high-dose use in patients with enuresis Not suitable for long-term or high-dose use in infants and the elderly Contraindicated in those with internal heat and dryness of essence and blood (from De Pei Ben Cao) Not to be used alone in cases of kidney deficiency with blazing fire; if necessary, combine with Zhimu (Anemarrhena) and Huangbai (Phellodendron) II. Cautious use populations Pregnant women may take it but not in excessive doses; nursing mothers should consult a physician III. Dietary restrictions Avoid spicy, greasy, and raw/cold foods during the course of medication IV. Drug interactions Should not be used together with antihypertensive drugs (e.g., reserpine, antihypertensive extract) Should not be used together with sedative-hypnotic drugs Should not be used together with antibiotics such as chloramphenicol and nitrofurantoin V. Overdose reactions Nausea, vomiting, diarrhea; long-term high-dose use may cause liver and kidney damage
Selected Formulas
1. Combined with walnut kernel (Hutaoren) and psoralea fruit (Buguzhi) – as in Qing'e Wan Action: Tonifies the kidney and strengthens the lower back. Indication: Kidney deficiency low back pain, soreness and weakness of the lower back and knees, flaccidity and weakness of the feet and knees. 2. Combined with angelica pubescens (Duhuo), Chinese taxillus herb (Sangjisheng), and asarum (Xixin) – as in Duhuo Jisheng Tang Action: Dispels wind-dampness, tonifies the kidney and strengthens the lower back. Indication: Cold and heavy rheumatic low back pain, wind-cold-dampness bi syndrome. 3. Combined with deer antler (Lurong), cornel fruit (Shanzhuyu), and dodder seed (Tusizi) – as in Shibu Wan Action: Warms the kidney and strengthens yang, consolidates essence and reduces urination. Indication: Kidney deficiency impotence, seminal coldness with insecurity, frequent urination. 4. Combined with Chinese taxillus herb (Sangjisheng), teasel root (Xuduan), and donkey-hide gelatin (Ejiao) Action: Tonifies the kidney and calms the fetus. Indication: Restless fetus (threatened miscarriage) and gestational bleeding due to liver-kidney deficiency with instability of the Chong and Ren meridians. 5. Combined with Chinese angelica (Danggui), Chuanxiong rhizome (Chuanxiong), and white peony root (Baishao) Action: Regulates menstruation and relieves pain. Indication: Low back pain during menstruation in women. 6. Combined with Chuanxiong rhizome (Chuanxiong), cinnamon bark (Guixin), and salvia root (Danshen) – as in Duzhong San Action: Activates blood circulation, removes stasis, unblocks meridians and relieves pain. Indication: Traumatic low back pain. 7. Combined with achyranthes root (Niuxi), goji berry (Gouqizi), and glossy privet fruit (Nvzhenzi) Action: Nourishes the liver and kidney. Indication: Liver-kidney deficiency with dizziness and blurred vision.
Daily Consumption
1. Du Zhong and Walnut Stewed Pig Kidney Ingredients: 1 pair of pig kidneys, 30 g Du Zhong (Eucommia bark), 20 g walnut kernels, appropriate amounts of salt, sesame oil, soy sauce, and coriander (cilantro). Preparation: Cook the pig kidneys together with Du Zhong, ginger, and scallion in water. Bring to a boil, skim off the foam. Add walnut kernels and salt, then reduce to low heat and simmer for 15 minutes. Remove the pig kidneys and slice. Arrange the kidney slices together with walnut kernels on a plate. Drizzle with sesame oil, soy sauce, and garnish with coriander. Action: Tonifies and nourishes the liver and kidney, strengthens sinews and bones. Indicated for soreness and pain of the lower back and spine. 2. Du Zhong Pork Kidney Flower (腰花) Ingredients: 1000 g pig kidneys, 12 g Du Zhong, 2 green bell peppers, appropriate amounts of scallion, ginger, chicken essence, salt, cooking wine (Shaoxing wine), monosodium glutamate (MSG, optional), cornstarch, soy sauce, sugar, and five‑spice powder. Preparation: Decoct Du Zhong in water for 20 minutes to obtain the liquid. Score the pig kidneys into a “flower” (grid) pattern, cut the green peppers into chunks, slice the scallion and ginger. Marinate the kidney pieces with cornstarch, chicken essence, salt, cooking wine, and MSG, then briefly stir‑fry in oil. In a wok, sauté the scallion, ginger, and green peppers, then add the kidney pieces and seasonings, stir‑fry quickly. Just before removing from heat, pour in the Du Zhong liquid. Action: Tonifies the kidney and supplements essence, strengthens bones and the body. Indicated for soreness and weakness of the lower back and knees, easy fatigue, impotence, spermatorrhea, edema, and frequent urination at night due to kidney yang deficiency. 3. Du Zhong, Orange Peel and Apricot Drink Ingredients: 6 g dried tangerine peel (Chenpi), 6 g sweet apricot seed (Tian Xingren), 6 g Du Zhong, 10 g old loofah (Luffa), appropriate amount of white sugar (optional). Preparation: Wash the old loofah, Du Zhong, and tangerine peel. Peel the apricot seed (remove skin). Place all ingredients in a clay pot, add 500 ml of water, bring to a boil over high heat, then reduce to low heat and simmer for 20–30 minutes. Strain and drink the liquid as tea. Sugar may be added to taste. Action: Tonifies the kidney and fortifies the spleen, dries dampness and transforms phlegm. Indicated for dizziness with a heavy sensation in the head, soreness and weakness of the lower back and legs due to internal accumulation of phlegm‑dampness. 4. Silver Ear Fungus and Du Zhong Thick Soup (Tremella and Eucommia Porridge) Ingredients: 6 g Ganoderma lucidum (Lingzhi), 6 g stir‑fried Du Zhong, 20 g lotus root starch (or arrowroot starch), 5 g white fungus (snow fungus / Tremella), appropriate amount of rock sugar (optional). Preparation: Wash the Du Zhong and Ganoderma, add 600 ml of water, decoct twice for 30 minutes each time, combine the decoctions and set aside. Soak the white fungus until soft, wash, and place in a pot with 200 ml of water. Simmer over low heat until the fungus becomes slightly yellow. Pour in the reserved decoction and continue to simmer for 20 minutes until the white fungus is soft and gelatinous. Thicken with lotus root starch (mixed with a little cold water) to make a thick soup. Sugar may be added to taste. Action: Nourishes the liver and kidney, supplements qi and relaxes sinews. Indicated for dizziness, headache, vertigo, tinnitus, and soreness of the lower back and knees due to liver‑kidney yin deficiency. 5. Du Zhong Tea Ingredients: 15 g Du Zhong, 30 g palm leaf (or other appropriate leaf), 5 g Prunella spike (Xiakucao). Preparation: Mix Du Zhong with salt water until absorbed, then stir‑fry in a dry wok over low heat until slightly charred. Remove and let cool. Grind together with palm leaf and Prunella spike into a coarse powder. Use the powder as a tea substitute (steep in boiling water and drink). Action: Acts as a tea substitute.
Medicinal Parts
dried bark
Selection & Storage
Store in a cool, well-ventilated, dry place, protected from moisture, mold, and insects. For salt-processed Eucommia bark (Yan Duzhong), keep in airtight containers in a well-ventilated, dry place. May also be refrigerated or stored in a cool, dry place.