Ingredient Processed / Derived product (加工品 jiā gōng pǐn)

E Jiao

Donkey-hide gelatin · 阿胶

Equus asinus L. · Asini Corii Colla

Also known as: Fù Zhì Jiāo (傅致胶), Pén Fù Jiāo (盆覆胶), Lǘ Pí Jiāo (驴皮胶),

E Jiao (Donkey-hide gelatin) plant

Images shown are for educational purposes only

One of the most prized Blood-nourishing substances in Chinese medicine, E Jiao is a gelatin made from donkey hide. It is widely used for blood deficiency conditions such as anemia and dizziness, various types of bleeding, dry cough, and restless insomnia due to Yin depletion. It has been considered a "blood tonic treasure" alongside ginseng and deer antler for over two thousand years.

Category Blood-tonifying herbs (补血药)
Therapeutic focus Anemia Support Menstrual Health Respiratory Health Sleep and Anxiety Support

TCM Properties

Temperature

Neutral

Taste

Sweet (甘 gān)

Channels entered

Lungs, Liver, Kidneys

Parts used

Processed / Derived product (加工品 jiā gōng pǐn)

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Educational content • Consult qualified TCM practitioners for diagnosis and treatment

What This Ingredient Does

Every ingredient has a specific set of actions — here's what E Jiao does in the body, explained in both everyday and TCM terms

Therapeutic focus

In practical terms, E Jiao is primarily used to support these areas of health:

Anemia Support Menstrual Health Respiratory Health Sleep and Anxiety Support

TCM Actions

In TCM terminology, these are the specific therapeutic actions that E Jiao performs to restore balance in the body:

Nourishes Blood Stops Bleeding Nourishes Yin Moistens Dryness Moistens the Lungs Calms the Fetus

How these actions work

'Tonifies Blood' means E Jiao directly nourishes and replenishes the Blood. As a 'blood-and-flesh' substance (a product derived from an animal rather than a plant), it has a special affinity for building Blood. This makes it particularly valuable for people with pale complexion, dizziness, heart palpitations, and fatigue caused by Blood deficiency. It is often considered the strongest single Blood-tonifying substance in the materia medica.

'Stops bleeding' refers to E Jiao's ability to help control various forms of abnormal bleeding, including coughing up blood, nosebleeds, blood in the stool or urine, and heavy or prolonged menstrual bleeding. Its sticky, glutinous quality is thought to help seal and consolidate the blood vessels. It is especially suited for bleeding that occurs alongside Blood deficiency or Yin deficiency, since it addresses both the symptom (bleeding) and the underlying weakness simultaneously.

'Nourishes Yin and moistens dryness' means E Jiao replenishes the body's fluids and moisture. This is why it is used for conditions involving internal dryness or depleted Yin, such as restlessness and insomnia after a prolonged fever, or dry cough with little or no phlegm. By restoring Yin fluids, it can also calm internal wind that arises from severe Yin exhaustion, helping to address tremors or spasms in late-stage febrile illness.

'Moistens the Lungs' means E Jiao specifically soothes and nourishes Lung tissue. When the Lungs are too dry or depleted of Yin, a persistent dry cough or coughing of blood can result. E Jiao's rich, moistening nature directly addresses this dryness, which is why classical physicians called it "an essential medicine for the Lung channel."

'Calms the fetus' refers to its traditional use for threatened miscarriage or bleeding during pregnancy. By nourishing Blood and stabilizing the Chong and Ren vessels (the channels closely linked to reproductive function), it helps secure the pregnancy.

Patterns Addressed

In TCM, symptoms cluster into recognizable patterns of disharmony. E Jiao is used to help correct these specific patterns.

Why E Jiao addresses this pattern

E Jiao is considered a premier Blood-tonifying substance. Its sweet taste nourishes and supplements, while its neutral temperature makes it suitable for Blood deficiency without generating excess Heat or Cold. As a 'blood-and-flesh' product, it has a particularly strong affinity for building Blood substance. It enters the Liver channel (the organ that stores Blood) and directly replenishes Blood volume and quality, addressing the root cause of this pattern.

A practitioner would look for one or more of these signs

Pallor

Pale or sallow complexion

Dizziness

Dizziness and lightheadedness

Severe Heart Palpitations

Palpitations from insufficient Blood to nourish the Heart

Insomnia

Difficulty sleeping due to Blood failing to anchor the spirit

Commonly Used For

These are conditions where E Jiao is frequently used — but only when they arise from the specific patterns it addresses, not in all cases

Arises from: Blood Deficiency

TCM Interpretation

TCM understands anemia primarily through the lens of Blood deficiency. Blood is produced through the cooperative function of the Spleen (which transforms food into the raw material for Blood), the Heart (which governs Blood circulation), and the Kidneys (which provide the foundational essence that supports Blood production). When any of these organ systems is weakened, Blood production or quality suffers. The Liver, which stores Blood, may also be involved. Symptoms like pallor, dizziness, palpitations, fatigue, and a pale tongue all point to insufficient Blood failing to nourish the body's tissues and organs.

Why E Jiao Helps

E Jiao is considered one of the strongest Blood-tonifying substances in the entire materia medica. As a 'blood-and-flesh' product (derived from an animal source), it is thought to have a special capacity to build Blood substance directly, unlike plant-based herbs that primarily support the organs responsible for Blood production. Its sweet taste nourishes and supplements, while its neutral temperature means it will not generate excess Heat or Cold. It enters the Liver channel (the primary Blood-storing organ) and the Kidney channel (the foundation of essence that supports Blood formation). Modern research has confirmed that it can accelerate recovery of red blood cells and hemoglobin in animal models of blood loss.

Also commonly used for

Dry Cough

Chronic dry cough from Lung dryness or Yin deficiency

Cough Of Blood

Hemoptysis from Lung Yin deficiency

Threatened Miscarriage

Threatened miscarriage with vaginal bleeding

Nosebleeds

Recurrent nosebleeds related to Blood Heat or Yin deficiency

Dark Blood In Stool

Chronic bloody stool from deficiency-type bleeding

Leukopenia

Low white blood cell count, particularly during chemotherapy

Dizziness

Dizziness and vertigo from Blood deficiency

Ingredient Properties

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

Temperature

Neutral

Taste

Sweet (甘 gān)

Channels Entered

Lungs Liver Kidneys

Parts Used

Processed / Derived product (加工品 jiā gōng pǐn)

Dosage & Preparation

These are general dosage guidelines for E Jiao — always follow your practitioner's recommendation, as dosages vary based on the formula and your individual condition

Standard dosage

5-15g

Maximum dosage

Up to 15g in decoction, or 30g in specialized formulas for severe Blood deficiency or hemorrhage, under practitioner supervision.

Dosage notes

Standard clinical dosage is 5-15g. Lower doses (3-6g) may suffice for mild Blood nourishment and Yin supplementation. Higher doses (10-15g) are used for active bleeding conditions or severe Blood deficiency. When used for hemostasis (stopping bleeding), E Jiao is often stir-fried with Pu Huang (cattail pollen), forming "E Jiao Zhu" (阿胶珠). For moistening the Lungs and resolving Phlegm, it is stir-fried with clam shell powder (蛤粉炒阿胶). The raw, unprocessed form is preferred for general Blood and Yin nourishment. E Jiao is cloying, so excessive dosage in patients with weak digestion can cause bloating, nausea, or loose stools. It is often combined with digestive aids like Chen Pi or Sha Ren to offset this tendency.

Preparation

E Jiao must NOT be decocted directly with other herbs. It should be dissolved separately (烊化兑服, yang hua dui fu): break it into small pieces, then dissolve in the hot, strained decoction liquid (or in hot water or warm rice wine) just before taking. This is because E Jiao's sticky gelatin will adhere to other herbs and to the pot if boiled together, wasting medicine and making the decoction difficult to strain. Processed forms such as E Jiao Zhu (stir-fried into puffed beads) can be added directly into decoctions or taken as powder in pills.

Processing Methods

In TCM, the same ingredient can be prepared in different ways to change its effects — here's how processing alters what E Jiao does

Processing method

E Jiao is cut into small cubes, then stir-fried with clam shell powder (Ge Fen) or cattail pollen (Pu Huang) over low heat until the pieces puff up into round beads that are no longer sticky inside.

How it changes properties

The temperature remains neutral but the puffed form is less cloying to the Spleen and Stomach, reducing the tendency to cause nausea or digestive discomfort. When processed with Pu Huang, the hemostatic (bleeding-stopping) action is enhanced. The puffed form dissolves more easily in decoctions and is less likely to stick to the pot.

When to use this form

Use when the patient has a weak Spleen and Stomach and cannot tolerate the raw gelatin's sticky, cloying nature. Also preferred when the primary goal is Lung moistening or stopping bleeding rather than heavy Blood tonification. The Pu Huang-fried form is specifically chosen when stopping bleeding is the priority.

Common Ingredient Pairs

These ingredients are traditionally combined with E Jiao for enhanced therapeutic effect

Ai Ye
Ai Ye E Jiao 9g : Ai Ye 9g (as in Jiao Ai Tang)

E Jiao nourishes Blood and stops bleeding through its rich, moistening nature, while Ai Ye warms the channels, dispels Cold, and strengthens the capacity of the uterus to contain Blood. Together they address both the deficiency and Cold aspects of uterine bleeding, warming and nourishing the Chong and Ren vessels simultaneously.

When to use: Heavy or prolonged menstrual bleeding, threatened miscarriage with vaginal bleeding, or postpartum bleeding, especially when there are signs of Cold such as cold lower abdomen and pale blood.

Huang Lian
Huang Lian Huang Lian 12g : E Jiao 9g (as in Huang Lian E Jiao Tang)

Huang Lian's bitter Cold nature powerfully clears Heart Fire and drains excess Heat, while E Jiao's sweet, moistening nature deeply nourishes Kidney Yin. Together they re-establish the Heart-Kidney axis by simultaneously draining the Fire above and replenishing the Water below.

When to use: Insomnia and restlessness caused by Yin deficiency with empty Fire, where the patient feels agitated, has a dry mouth, and cannot sleep despite feeling exhausted. The tongue is typically red with little coating.

Pu Huang
Pu Huang E Jiao 9g : Pu Huang 9g

Pu Huang (cattail pollen) invigorates Blood and stops bleeding through its astringent action, while E Jiao nourishes Blood and stops bleeding through its consolidating, moistening quality. Together they stop bleeding without causing stasis, and replenish Blood that has been lost.

When to use: Hematemesis, epistaxis, or hematuria with signs of Blood Heat and concurrent Blood deficiency.

Shu Di Huang
Shu Di Huang Sheng Di Huang 18g : E Jiao 9g (as in Da Ding Feng Zhu)

Sheng Di Huang (raw Rehmannia) cools Blood Heat, generates fluids, and nourishes Yin, while E Jiao tonifies Blood and moistens dryness. Together they provide powerful Yin and Blood nourishment with an ability to cool Blood Heat and stop bleeding driven by Heat.

When to use: Bleeding due to Blood Heat (vomiting blood, nosebleeds) accompanied by Yin deficiency signs, or for Yin-deficient internal wind conditions.

Key Formulas

These well-known formulas feature E Jiao in a prominent role

Da Ding Feng Zhu 大定風珠 King

From Wu Jutong's Wen Bing Tiao Bian, this formula treats critical Yin deficiency with internal wind after prolonged febrile disease. E Jiao serves as co-King with egg yolk (Ji Zi Huang), both being 'blood-and-flesh' substances that powerfully replenish the nearly exhausted true Yin. This formula showcases E Jiao's role in the most severe Yin-depleted situations.

Bu Fei E Jiao Tang 補肺阿膠湯 King

Originally named E Jiao San from Qian Yi's Xiao Er Yao Zheng Zhi Jue, this formula highlights E Jiao's Lung-moistening action. It treats Lung Yin deficiency with cough, wheezing, and blood-streaked sputum. E Jiao serves as King at a large dose, directly nourishing and moistening the Lungs.

Huang Lian E Jiao Tang 黃連阿膠湯 Deputy

A classic Shang Han Lun formula for Yin deficiency with Fire flaring, causing severe insomnia and restlessness. While Huang Lian is the King herb clearing Heart Fire, E Jiao plays a crucial Deputy role nourishing Kidney Yin to restore Heart-Kidney communication. This formula highlights E Jiao's Yin-nourishing capacity rather than its Blood-tonifying role.

Comparable Ingredients

These ingredients have overlapping uses — here's how to tell them apart

Shu Di Huang
E Jiao vs Shu Di Huang

Both are premier Blood-tonifying substances, but they differ in nature and additional actions. E Jiao is neutral, also stops bleeding and moistens the Lungs, and is a 'blood-and-flesh' product with a particular affinity for building Blood substance directly. Shu Di Huang (prepared Rehmannia) is warm, more focused on nourishing Liver and Kidney Yin-essence and filling the marrow, but is heavier and more cloying to the Spleen. E Jiao is preferred when bleeding is present alongside Blood deficiency, while Shu Di Huang is preferred for deep Kidney essence deficiency.

Dang Gui
E Jiao vs Dang Gui

Both tonify Blood, but Dang Gui is warm and also invigorates Blood circulation and relieves pain, making it better suited for Blood stasis patterns with pain (such as painful menstruation). E Jiao is neutral and has stronger Blood-building and bleeding-stopping actions but does not move Blood. For purely deficient Blood without stasis, or when bleeding is the concern, E Jiao is preferred. For Blood deficiency with stasis or pain, Dang Gui is better.

Long Yan Rou
E Jiao vs Long Yan Rou

Both tonify Blood with a sweet taste, but Long Yan Rou (longan fruit) is warm and also tonifies the Heart and calms the spirit, making it well-suited for Heart-Spleen deficiency with insomnia and poor appetite. It is much milder in Blood-tonifying power and has no hemostatic action. E Jiao is far stronger for Blood deficiency, has significant bleeding-stopping and Yin-nourishing actions, and enters the Lung channel for respiratory conditions.

Common Substitutes & Adulterants

Related species and common adulterations to be aware of when sourcing E Jiao

E Jiao is one of the most frequently adulterated medicines in China due to its high price and the global shortage of donkey hides. Common adulterants include gelatin made from horse hide, mule hide, pig hide, cow hide, or even old leather products. Historically, Li Shizhen noted that fake E Jiao was already widespread in the Ming Dynasty. Modern analytical methods using LC-MS/MS can identify species-specific peptide markers (e.g., GPTGEPGKPGDK for donkey, GPSGEPGKPGDK for horse, GEAGPSGPAGPTGAR for cow, GEGGPQGP for cow, and GPTGPAGVR for pig) to detect adulteration even at levels as low as 0.5%. Legitimate substitutes used in clinical practice include: - Huang Ming Jiao (黄明胶, cow-hide gelatin): first recorded in the Tang-dynasty Shi Liao Ben Cao, similar properties and functions to E Jiao, used as a substitute when E Jiao is unavailable. - Xin A Jiao (新阿胶, pig-skin gelatin): first recorded in the Ben Cao Gang Mu under the name "pig-skin glue" (猪皮胶), a less expensive alternative. Authentic E Jiao should be purchased from reputable manufacturers. The leading producer, Dong-E-E-Jiao Co. Ltd., uses DNA molecular identification and chromatographic methods to ensure product authenticity.

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

Toxicity Classification

Classical Chinese pharmacopoeia toxicity rating for E Jiao

Non-toxic

E Jiao is classified as non-toxic in the Chinese Pharmacopoeia. As a gelatin product composed primarily of collagen-derived amino acids and proteins, it contains no known toxic alkaloids or harmful compounds. Clinical trials and animal studies have confirmed that standard doses do not produce adverse effects. The main concern is not toxicity but rather its rich, sticky nature, which can impair digestion in people with weak Spleen and Stomach function, potentially causing nausea, bloating, or loose stools. Some users report a sensation of internal heat (上火) after taking E Jiao, but controlled studies have not found a statistically significant increase in fire-heat symptoms compared to placebo.

Contraindications

Situations where E Jiao should not be used or requires extra caution

Caution

Spleen and Stomach weakness with poor digestion: E Jiao is sticky and cloying by nature, which can obstruct the Spleen and Stomach, worsening symptoms like bloating, poor appetite, loose stools, or nausea. Classical sources such as the Ben Cao Jing Shu state that those with a weak Stomach prone to vomiting should not take it.

Caution

Phlegm-Damp or Damp-Heat patterns: the rich, sticky nature of E Jiao can trap Dampness and make these conditions worse. It should be avoided in people with heavy feelings in the limbs, thick greasy tongue coating, or signs of Damp accumulation.

Caution

Exterior patterns (colds and flu with active symptoms): using E Jiao during the early stages of an exterior pathogen invasion can trap the pathogen inside the body. Classical teaching warns that when pathogenic factors are dominant at onset, using E Jiao may close the door on the pathogen and create new problems.

Avoid

Known allergy to gelatin or donkey-derived products: individuals with a history of allergic reactions to animal gelatins should avoid E Jiao.

Caution

Uterine fibroids or estrogen-sensitive conditions: pharmacological studies suggest E Jiao may promote endometrial growth and increase estradiol levels. Many TCM practitioners advise caution or avoidance in patients with uterine fibroids, endometrial hyperplasia, or other estrogen-dependent conditions.

Caution

Phlegm with Cold or retained fluid (Han Tan Liu Yin): the Ben Cao Hui Yan specifically warns against using E Jiao when there is Cold Phlegm or retained Yin fluids in the Stomach.

Special Populations

Important considerations for pregnancy, breastfeeding, and pediatric use

Pregnancy

E Jiao has been traditionally used during pregnancy and is generally considered safe and even beneficial for pregnant women. Classical texts consistently describe it as a medicine that "calms the fetus" (安胎). It appears in famous classical formulas for pregnancy-related bleeding, such as Jiao Ai Tang (胶艾汤) from the Jin Gui Yao Lue, used for threatened miscarriage and uterine bleeding. The Ben Cao Gang Mu records E Jiao combined with Ai Ye (mugwort leaf) for stabilizing pregnancy. However, some pharmacological studies suggest E Jiao may promote endometrial growth and increase estradiol levels, so use during pregnancy should still be under practitioner supervision to ensure appropriate pattern differentiation. Not recommended for self-medication during pregnancy without professional guidance.

Breastfeeding

E Jiao is generally considered compatible with breastfeeding. As a collagen-based gelatin rich in amino acids, it does not contain known harmful compounds that would pose a risk through breast milk. In traditional practice, it is commonly used in the postpartum period to help replenish Blood lost during childbirth and support recovery. Compound E Jiao preparations (such as Fufang E Jiao Jiang) have been used to treat postpartum anemia. However, its rich and cloying nature may cause digestive discomfort in the mother, which could indirectly affect milk quality. As always, use under practitioner guidance is advisable.

Children

E Jiao has been used in classical pediatric formulas. For example, Bu Fei E Jiao Tang (补肺阿胶汤) from Qian Yi's Xiao Er Yao Zheng Zhi Jue (《小儿药证直诀》) uses E Jiao for pediatric Lung deficiency with cough. Li Shizhen also noted its use for children's post-convulsion eye disorders. Dosage for children should be significantly reduced from the adult range, typically 2-5g depending on the child's age and weight, and always under practitioner supervision. Its sticky, cloying nature makes it particularly important to assess the child's digestive function before use, as children's Spleen and Stomach function is characteristically immature.

Drug Interactions

If you are taking pharmaceutical medications, be aware of these potential interactions with E Jiao

No well-documented severe drug interactions have been established for E Jiao in peer-reviewed pharmacological literature. However, theoretical considerations based on its known properties warrant caution in the following situations:

  • Anticoagulant and antiplatelet medications (e.g. warfarin, aspirin, clopidogrel): E Jiao is used traditionally to both stop bleeding and nourish Blood. Its collagen-derived components could theoretically interact with drugs affecting coagulation. Patients on blood-thinning medications should inform their physician before taking E Jiao.
  • Estrogen-related therapies (hormone replacement therapy, oral contraceptives): Pharmacological studies have found that E Jiao may increase estradiol levels and promote endometrial growth. This could potentially have additive effects with exogenous estrogen therapies.
  • Iron supplements: E Jiao is rich in amino acids (particularly glycine) that may enhance calcium and potentially iron absorption. While this is generally beneficial, it may alter the pharmacokinetics of concurrently administered mineral supplements.

Overall, robust clinical data on E Jiao drug interactions is lacking. Patients taking any pharmaceutical medications should consult their healthcare provider before adding E Jiao.

Dietary Advice

Foods and dietary considerations when taking E Jiao

While taking E Jiao, avoid excessive consumption of cold and raw foods (such as raw salads, iced drinks, and cold fruit) as these can impair the Spleen's digestive function, compounding E Jiao's naturally cloying quality. Strong tea should be avoided around the time of ingestion, as tannins may interfere with protein absorption. Radish (turnip) is traditionally avoided during E Jiao supplementation, as it is considered to counteract the tonic effect. Warm, easily digestible foods are favored. Pairing E Jiao with a small amount of Chen Pi (tangerine peel) tea or ginger can help offset any digestive heaviness.

Botanical Description

Physical characteristics and morphology of the E Jiao source source material

E Jiao (阿胶, Asini Corii Colla) is not derived from a plant but from an animal source. It is a solid gelatin prepared from the hide of the donkey (Equus asinus L., family Equidae). The donkey is a domesticated member of the horse family, typically smaller than horses (around 200 kg), with long ears, a sturdy body, short mane, and a tail with long hair at the tip. Coat color is usually black, chestnut-brown, or grey. The famous Guanzhong (关中) donkey breed, prized for its large size and high-quality hide, has been historically associated with E Jiao production.

The raw donkey hide is collected, soaked in water to soften it, and the hair is removed. The cleaned hide is then cut into small pieces and boiled repeatedly in water (traditionally using the mineral-rich well water of Dong'e County, Shandong Province). The gelatin is separated, concentrated with additives such as rice wine, rock sugar, and soybean oil, then cooled, shaped into rectangular blocks, and air-dried to produce the final medicinal product.

Sourcing & Harvesting

Where E Jiao is sourced, when it's harvested or collected, and how to assess quality

Harvesting season

Donkey hides are collected year-round, but traditional production of the highest quality E Jiao occurs from the winter solstice through early March, when the mineral-rich well water is considered at its best quality.

Primary growing regions

The finest E Jiao (道地药材) has traditionally come from Dong'e County (东阿县) in Shandong Province, China, where the local well water (阿井水) is rich in minerals such as calcium, magnesium, and potassium. This mineral-rich groundwater has long been considered essential for producing the highest quality product. The name "E Jiao" itself derives from the ancient county name "E" (阿). Shandong Province remains the primary and most famous production region, with Dong-E-E-Jiao Co. Ltd. being the leading manufacturer. Zhejiang Province also produces large quantities. Other production sites include Shanghai, Beijing, Tianjin, and Shenyang.

Quality indicators

Good quality E Jiao comes in neat rectangular blocks, approximately 8.5 cm long, 3.7 cm wide, and 0.7-1.5 cm thick. The surface should be dark brown to jet black (乌黑), smooth, and glossy with a lustrous sheen. When held up to light, authentic E Jiao should be slightly translucent, showing a semi-transparent brownish appearance. The texture should be firm and brittle, snapping cleanly when broken. The fracture surface should be smooth and shiny, matching the exterior color. The taste should be mildly sweet with very little odor and absolutely no fishy or foul smell. Critically, high-quality E Jiao should not soften or become sticky in summer heat (经夏不软). The most prized variety is "Dong'e Jiao" (东阿胶) made with authentic Dong'e well water.

Classical Texts

Key passages from the classical Chinese medical texts that describe E Jiao and its therapeutic uses

Shen Nong Ben Cao Jing (《神农本草经》)

Chinese: 主心腹内崩，劳极洒洒如疟状，腰腹痛，四肢酸疼，女子下血。安胎。久服轻身益气。

English: It treats internal collapse of the chest and abdomen, extreme exhaustion with chills resembling malaria, pain in the lower back and abdomen, soreness of the four limbs, and uterine bleeding in women. It calms the fetus. Long-term use lightens the body and boosts Qi.

Ben Cao Gang Mu (《本草纲目》), Li Shizhen

Chinese: 阿胶，大要只是补血与液，故能清肺益阴而治诸证。

English: The essential function of E Jiao is simply to nourish the Blood and body fluids, and therefore it can clear the Lungs, benefit the Yin, and treat various conditions.

Tang Ye Ben Cao (《汤液本草》)

Chinese: 阿胶益肺气，肺虚极损，咳嗽唾脓血，非阿胶不补。

English: E Jiao benefits the Lung Qi. When the Lungs are severely depleted, with coughing and spitting of pus and blood, nothing but E Jiao can tonify [the Lungs].

Attributed to Cheng Wuji (成无己)

Chinese: 阴不足者，补之以味，阿胶之甘，以补阴血。

English: When Yin is insufficient, supplement it with flavor. The sweetness of E Jiao supplements the Yin and Blood.

Yang Shiying (杨士瀛), Song Dynasty

Chinese: 凡治喘嗽，不论肺虚、肺实，可下可温，须用阿胶以安肺润肺，其性和平，为肺经要药。

English: In all cases of wheezing and cough, whether from Lung deficiency or excess, whether the treatment calls for purging or warming, E Jiao should be used to calm and moisten the Lungs. Its nature is gentle and balanced, making it an essential medicine for the Lung channel.

Historical Context

The history and evolution of E Jiao's use in Chinese medicine over the centuries

E Jiao is one of the oldest continuously used medicinal substances in the Chinese tradition, with a history spanning over 2,000 years. Its name derives from the ancient county of E (阿, in modern Dong'e, Shandong), where it was first produced. The character "胶" (jiāo) means "glue" or "gelatin." Tao Hongjing, the Six Dynasties-era physician, noted: "It comes from Dong'e, hence the name E Jiao" (出东阿，故名阿胶). It was classified as an "upper grade" (上品) medicine in the Shen Nong Ben Cao Jing, indicating it was considered safe for long-term use and broadly nourishing.

Interestingly, E Jiao was originally made from cow hide. The transition to donkey hide occurred gradually during the Tang Dynasty, when practitioners found donkey skin produced a gelatin with superior medicinal properties. Li Shizhen noted in the Ben Cao Gang Mu that ancient formulas mostly used cow skin, but later generations came to value donkey skin more highly. He listed E Jiao alongside Ren Shen (ginseng) and Lu Rong (deer antler velvet) as the "three treasures of tonification" in Chinese medicine. From the Song Dynasty onward, Five Phases (Wu Xing) theory was increasingly used to explain why black donkey hide was considered essential: black corresponds to Water and the Kidneys, thereby enhancing E Jiao's Yin-nourishing properties. Traditionally, the best E Jiao was made only from late autumn through early spring (roughly winter solstice to March), and the imperial court controlled access to the Dong'e well.

The Qing-dynasty physician Chen Xiuyuan offered an elegant theoretical explanation: the donkey belongs to the horse family (Fire), yet its hide is worked with the deep, still water of the Dong'e well, so "stillness controls movement, and Wind and Fire are extinguished while Yin Blood is generated." E Jiao remains one of the most commercially significant traditional medicines in China today, with its demand contributing to significant global impact on donkey populations.

Modern Research

4 published studies investigating the pharmacological effects or clinical outcomes of E Jiao

1

Efficacy and Safety of Ejiao in Women With Blood Deficient Symptoms: A Randomized, Double-Blind, and Placebo-Controlled Clinical Trial (RCT, 2021)

Zhang L, Xu Z, Jiang T, et al. Frontiers in Pharmacology, 2021, Volume 12, Article 718154.

This RCT recruited 210 women with TCM Blood Deficiency symptoms and randomly assigned them to receive Ejiao (6 g/day) or placebo for 8 weeks. The Ejiao group showed significantly improved dizziness symptoms and better maintenance of hematocrit and red blood cell counts compared to placebo. Quality of life scores also improved. No significant increase in fire-heat symptoms or safety concerns was observed.

2

Blood-supplementing effect of low molecular weight peptides of E-Jiao on chemotherapy-induced myelosuppression (Preclinical, 2024)

Zhang J, Lin D, Wu Y, et al. Frontiers in Pharmacology, 2024, Volume 15, Article 1366407.

This study used zebrafish and mouse models to investigate which components of E Jiao are responsible for its blood-nourishing effects. Researchers identified low molecular weight peptides derived from type I collagen as the active fraction. Two specific peptides absorbed into rat blood were shown to protect zebrafish from chemotherapy-induced myelosuppression by increasing red blood cell or neutrophil counts. Network pharmacology suggested mechanisms involving Nrf2/ARE antioxidant signaling.

PubMed
3

Ejiao as a preventive agent for osteoporosis: a scoping review (Scoping Review, 2025)

Wang Y, Chen G, Ji X, Wong SK, Ekeuku SO, Chin KY. Journal of Orthopaedic Surgery and Research, 2025, 20(1):445.

This scoping review systematically evaluated the current evidence on E Jiao's potential bone-protective properties. Searching PubMed, Scopus, and CNKI through October 2024, it included 22 studies (5 on Ejiao alone, 17 on Ejiao-based formulations). The review found emerging evidence that Ejiao and its formulations may have anti-osteoporotic effects, warranting further clinical investigation.

4

A Comprehensive Review of Ejiao: Chemical Composition, Quality Control, and Pharmacological Actions (Review, 2025)

Wang Y, Chen G, Wang Q, et al. Natural Product Communications, 2025, 20(1), 1934578X251335424.

This comprehensive review analyzed Ejiao's chemical composition, which includes 19 amino acids, over 2,000 peptides, 12 polysaccharides, and over 100 volatile components. Pharmacological evidence was summarized for blood-nourishing, anti-anemic, lung-protective, anti-aging, antioxidant, immune-modulating, anti-tumor, anti-osteoporotic, and estrogenic effects. Quality control methods using chromatography-mass spectrometry and DNA molecular identification were also reviewed.

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