Traditionally used for
- Dizziness
- Cough & breathing
- Bowel health
- Menstrual & women's health
- Heart & circulation
- Energy & fatigue
☯ TCM Properties
Nourishes Blood; Stops Bleeding; Nourishes Yin; Moistens Dryness; Moistens the Lungs; Calms the Fetus
Traditional Chinese Uses
E Jiao (donkey-hide gelatin, ass-hide glue) is a warm, sweet substance considered one of the three most important Blood tonics in Chinese medicine — alongside Shu Di Huang and He Shou Wu. It nourishes Blood and Yin, stops bleeding by stabilizing the Chong channel, and moistens dryness. It is used for Blood deficiency patterns with pallor, dizziness, and palpitations; for uterine bleeding and heavy menstruation from Blood deficiency; and for cough or constipation from Lung or Intestinal Yin dryness. Its gelatinous, nourishing character makes it a revered tonic for depleted conditions.
Used In Formulas (8)
Relationships
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Botanical Description
E Jiao is a solid glue-like gelatin prepared by prolonged simmering of the cleaned and soaked hides of donkeys (Equus asinus), with the resulting decoction skimmed, concentrated, clarified, and poured into molds where it cools into translucent dark-amber to nearly black rectangular blocks with a glossy, slightly brittle texture. Traditionally the highest grades originate from Dong'e County in Shandong Province, where local well water is said to give the finished product its characteristic clarity. The blocks are broken into pieces for clinical use or stir-fried with clamshell powder into pearly beads. In Traditional Chinese Medicine, E Jiao is sweet in flavor and neutral in nature, entering the Lung, Liver, and Kidney channels; it tonifies blood, nourishes Yin, moistens dryness, and stops bleeding, especially in deficiency-pattern hemorrhage.
Active Constituents
Type I collagen (alpha1(I) and alpha2(I) chains) and its hydrolysis peptides
Structural protein and derived peptidesConcentration: protein is typically 70-90% of commercial Ejiao; over 2000 peptides have been catalogued in the drug
Ejiao is donkey hide boiled down to a gelatin, so it is essentially hydrolysed type I collagen. Collagen alpha1(I), alpha2(I) and albumin have been identified directly by proteomics. The peptide fraction, not intact collagen, is what is absorbed, and low-molecular-weight Ejiao peptides are the material investigated for the drug's haematopoietic effects in myelosuppression models.
Glycine
Amino acidConcentration: about 19% of the total amino acids of the drug
The most abundant amino acid, as expected from the Gly-X-Y repeat of collagen. Total amino acid content of hydrolysed Ejiao has been measured at 51.9-82.0%, across 19 amino acids including nine essential ones. Glycine dominance is one of the simplest checks that a sample really is a hide gelatin, though it does not identify the species.
Proline
Amino acidConcentration: about 12% of the total amino acids of the drug
The X position residue of the collagen triple helix repeat, and second only to glycine in abundance. Like glycine it confirms gelatin identity but is common to donkey, horse, cattle and pig hide alike, so it cannot distinguish genuine Ejiao from its substitutes.
Hydroxyproline
Post-translationally modified amino acidConcentration: present as the Y position residue of the collagen repeat; used as a quantitative marker rather than reported as a fixed percentage
The fingerprint amino acid for collagen, since it occurs in essentially no other dietary protein at comparable levels. Hydroxyproline assay is therefore the standard way to confirm that a product is a collagen preparation, and to detect dilution with non-collagen protein or with starch.
Donkey-specific collagen marker peptides
Species-diagnostic tryptic peptidesConcentration: four donkey-specific marker peptides identified alongside one horse-specific, three cattle-specific and six pig-specific peptides
These are the only constituents that establish species identity. Detection limits of 0.02-0.05 mg per marker allow LC-MS/MS to quantify how much of a product is genuinely donkey and how much is horse, cattle or pig gelatin; a separate marker-peptide method detects cattle or pig hide gelatin in Ejiao at 0.1% and horse hide at 0.5%. Real-time PCR against single-copy nuclear genes gives an independent DNA-based check.
Ejiao polysaccharides and trace elements
Polysaccharide and inorganic minor componentsConcentration: twelve polysaccharides and assorted trace elements and fatty acids reported, alongside over one hundred volatile components
Minor by mass but part of why a decocted glue is not simply equivalent to a purified collagen hydrolysate. Donkey-hide gelatin hydrolysates show high iron-binding affinity, which is the current mechanistic proposal for the drug's traditional blood-nourishing action, working through improved iron bioavailability rather than by supplying iron itself.
⚠ Drug Interactions
Bovine (cattle) hide gelatin substituted for donkey hide
Demand for Ejiao vastly exceeds donkey supply, so substitution is the norm rather than the exception. In a marker-peptide survey of 110 commercial Ejiao samples analysed by LC-QTOF-MS/MS and scheduled MRM, 57 samples (51.8%) were adulterated, of which 45 were cattle gelatin products; one sample contained no gelatin at all. Cattle-hide glue is itself a separate classical drug (Huang Ming Jiao) with different traditional indications, so this is a substitution of one drug for another and not merely a purity issue.
Clinical note: Treat any Ejiao without batch-level species verification as probably not donkey. This matters directly for patients who avoid beef on religious or personal grounds, and for anyone with a beef or bovine gelatin sensitivity. Ask suppliers for LC-MS/MS marker peptide or real-time PCR results, not just a certificate of origin.
Porcine (pig) hide gelatin substituted for donkey hide
Pig-specific marker peptides were among the fourteen species markers developed for Ejiao authentication, and pig or pig-and-horse gelatin blends were identified in the same 110-sample commercial survey in which 51.8% of products were adulterated. Marker peptide LC-MS/MS detects pig hide gelatin in Ejiao down to 0.1%. Because the finished glue is an opaque dark block, there is no organoleptic way for a patient or practitioner to detect this.
Clinical note: For any patient with a religious or ethical prohibition on pork, do not dispense Ejiao unless the batch has species verification. Raise the possibility proactively rather than waiting to be asked, since patients will not expect a blood tonic to contain pig.
Horse hide gelatin (Colla Corii Equi) substituted for donkey hide
Horse and donkey are congeneric, so their collagen sequences are the most similar of the common substitution pairs and horse gelatin has the highest detection limit, 0.5% versus 0.1% for cattle and pig by marker peptide LC-MS/MS. The commercial survey found five horse gelatin products, three pig and horse blends, one cattle and horse blend and two products containing both donkey and horse gelatin, so partial dilution with horse is common.
Clinical note: Insist on a method validated for equid discrimination, since a generic gelatin test will not separate horse from donkey. Suspect partial horse dilution in any product priced well below the market for genuine Ejiao.
Ejiao of unverified provenance and international donkey-skin trade restrictions
Ejiao production consumes an estimated 4 to 6 million donkey hides a year, close to a tenth of the global donkey population, and equine welfare organisations put worldwide slaughter for the trade at around 5.9 million donkeys annually. The African Union assembly meeting in Addis Ababa in February 2024 adopted a continent-wide moratorium on slaughtering donkeys for their skins, following national bans by exporting countries including Niger and Burkina Faso in 2016 and Kenya in 2020. An AU-IBAR report prepared with the International Coalition for Working Equids projects that Africa's donkey population could fall from roughly 27 million to 14 million by 2040 if the moratorium is not enforced. The welfare and livelihood consequences are documented and substantial, because donkeys in exporting countries are working animals whose loss falls on the poorest households, and because post-moratorium illegal slaughter continues. This is a supply-chain and legal matter rather than a pharmacological one, but it is the direct cause of the adulteration hazard above.
Clinical note: Ask suppliers where the hides came from, not only what species they are. Where a Blood-nourishing and Yin-nourishing effect is the aim, discuss with the patient whether a plant-based strategy is acceptable, since many patients would not choose this drug if told what the supply chain involves.
Oral iron salts and iron-deficiency treatment
Donkey-hide gelatin hydrolysates have high iron-binding affinity in vitro, and in rodent models markedly enhanced haematopoiesis and iron homeostasis with a reported 44% rise in haemoglobin and normalised serum ferritin. Peptide chelation can either enhance iron uptake or sequester it depending on the peptide and the iron species, and no human study has measured iron pharmacokinetics with concurrent Ejiao, so the direction of effect in a patient on ferrous sulphate is unknown.
Clinical note: There is no evidence of harm. Recheck haemoglobin and ferritin on the usual schedule rather than assuming Ejiao is inert, and do not let it displace iron replacement in documented iron-deficiency anaemia.
Dosage
| Form | Amount | Frequency | Duration | Population | Notes |
|---|---|---|---|---|---|
| decoction | 3–9 g | Daily | — | — | 中国药典 2020 【用法与用量】3～9g。烊化兑服。 【性味与归经】甘，平。归肺、肝、肾经。 — Chinese Pharmacopoeia 2020, quoted verbatim; route and cautions preserved. Replaces a cleared category-filler value. |
Dui Yao — Herb Pairs
The classical two-herb combinations this herb appears in, each with an action neither herb has alone.
The combination warms the channels and nourishes blood while stopping bleeding, securing the Chong and Ren vessels.
Uterine bleeding, prolonged spotting and threatened miscarriage with bleeding from deficiency cold of the Chong and Ren.
Core pair of a classical formula — Jiao Ai Tang (Xiong Gui Jiao Ai Tang), Jin Gui Yao Lue (Zhang Zhongjing)
Together they drain Heart fire and nourish yin and blood, calming the spirit when excess fire and deficient yin coexist.
Classic indication: irritability and insomnia from yin deficiency with blazing Heart fire.
Core pair of a classical formula — Huang Lian E Jiao Tang, Shang Han Lun (Zhang Zhongjing)
Yin and blood are richly nourished to extinguish internal wind arising from exhausted yin.
Also paired in Huang Lian E Jiao Tang.
Core pair of a classical formula — Da Ding Feng Zhu, Wen Bing Tiao Bian (Wu Jutong)
Evidence Tier
Moderate evidence · 3 studiesRecorded studies by study design, strongest design at the top. This is a study-design tier only, not a GRADE rating: it does not weigh risk of bias, consistency or precision.
Systematic review / meta-analysis
0
Randomized controlled trial
1
0 verified · 1 unverified
Other clinical trial
0
Observational / case report
0
In vitro / animal
2
2 verified · 0 unverified
Other / unclassified
0
Verified: design read from PubMed for a DOI that resolves to the cited paper Unverified: taken from the study's recorded description
Clinical Studies
Efficacy and Safety of Ejiao (Asini Corii Colla) in Women With Blood Deficient Symptoms: A Randomized, Double-Blind, and Placebo-Controlled Clinical Trial
Randomised, double-blind, placebo-controlled trial in 210 participants with blood deficiency pattern, mainly women, taking 6 g of Ejiao daily or placebo for eight weeks; 181 completed (119 Ejiao, 62 placebo). Dizziness improved significantly in the Ejiao arm, with moderate-severity dizziness falling to 6.5% versus 14.5% in controls at day 56. Red cell count and haematocrit declined in both arms but significantly less on Ejiao, and SF-36 vitality, social function and role-emotional scores improved by week 4. Eleven adverse events occurred on Ejiao versus four on placebo (not significant), most commonly dry skin and facial acne; liver and kidney function stayed normal. Note that the haematological result is a smaller decline rather than a rise, so this does not establish Ejiao as a treatment for anaemia.
Qualitative and Quantitative Analysis of Ejiao-Related Animal Gelatins through Peptide Markers Using LC-QTOF-MS/MS and Scheduled Multiple Reaction Monitoring (MRM) by LC-QQQ-MS/MS
Fourteen species-specific marker peptides were identified from eleven laboratory-made animal hide gelatins and four reference standards: four donkey-specific, one horse-specific, three cattle-specific and six pig-specific. Detection limits were 0.05 mg for the donkey marker and 0.02-0.03 mg for the horse, cattle and pig markers. Applied to 110 commercial Ejiao samples, 57 (51.8%) were adulterated: 45 cattle gelatin, 5 horse, 3 pig and horse blends, 1 cattle and horse blend, 2 containing both donkey and horse, and 1 containing no gelatin at all. This is the clearest published measure of how often Ejiao on the market is not donkey hide.
Species-specific identification of donkey-hide gelatin and its adulterants using marker peptides
Twelve species-specific marker peptides were identified for donkey-hide gelatin and its adulterants from donkey, horse, cattle and pig, and one marker per species was taken forward into an LC-MS/MS method. The method detected cattle-hide and pig-hide gelatin added to donkey-hide gelatin at 0.1%, and horse-hide gelatin at 0.5%, the higher limit for horse reflecting how close equid collagen sequences are. It gives practitioners a concrete specification to demand from suppliers.
Historical Texts
Shen Nong Ben Cao Jing
Han dynastyMing Yi Bie Lu
Southern dynasties (Tao Hongjing, c. 500 CE)Ben Cao Gang Mu
Ming dynasty (Li Shizhen, 1596)References
- Yuanzhong Wang, Guiju Chen, Qin Wang, Zaifu Zhou, Wenjian Zhao, Sok Kuan Wong, Tao Wang, Kok-Yong Chin. A Comprehensive Review of Traditional Chinese Medicine Ejiao (Colla Corii Asini): Chemical Composition, Quality Control, and Pharmacological Actions . Natural Product Communications (2025) [DOI]
- Lauren A. Johnston. China, Africa, and the Market for Donkeys: Why Did the African Union Ban the Ejiao-Linked Donkey Hide Trade? . Journal of Contemporary China (2024) [DOI]
- Hao-Bin Lin, Chun-Yan Peng, Hui Wang, Yang-En Sun, Xiao-Bo Duan, Hai-Bin Liu, Xin-Yi Lin, Le-Ying Yang, Zong-Cai Tu, Xiao-Mei Sha. Stability and iron affinity of Donkey-hide gelatin hydrolysates: Implications for improving iron bioavailability and gut microbiota modulation . npj Science of Food (2025) [DOI]
This information is for educational purposes only and is not intended to replace professional medical advice. Always consult a qualified healthcare provider before using any herbal remedy, especially if you are pregnant, nursing, or taking medications.
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