Yan Hu Suo
StarCorydalis yanhusuo W.T.Wang
Traditionally used for
- Digestion
- Menstrual & women's health
- Sleep
- Pain & joints
- Heart & circulation
Cautions & contraindications
- Pregnancy
- Young children
- Liver conditions
☯ TCM Properties
Invigorates Blood and Dispels Stasis; Moves Qi; Alleviates Pain
Traditional Chinese Uses
Yan Hu Suo (corydalis rhizome) is one of the most powerful analgesic herbs in Chinese medicine, used wherever pain from Blood and Qi stagnation is the primary complaint. It addresses menstrual pain, postpartum abdominal pain, chest pain, and pain from traumatic injuries — all conditions where stagnant Qi and Blood are obstructing the free flow through the channels. Modern pharmacology has confirmed its potent alkaloid-based pain-relieving mechanism, and it is widely used in modern Chinese clinical practice for various pain conditions.
Western Herbalism Properties
Pharmacological Effects
- Analgesic: Powdered herb orally in mice was analgesic at 1/10 the potency of opium, lasting 2 h; dl-THP (15-20 mg/kg i.v.) and d-corydaline analgesic in rabbits; protopine ED50 27 mg/kg i.p. in mice; rats developed tolerance but not addiction to dl-THP.
- Hypnotic, sedative and tranquilizing: l-THP was sedative/tranquilizing in mice by blocking postsynaptic dopamine receptors without depleting monoamines; large dl-THP doses were hypnotic in rabbits, dogs and monkeys; d-THP inactive.
- Muscle relaxant: Protopine relaxed guinea pig ileum (IC50 3.4 and 5.1 µM vs acetylcholine and BaCl2) and cat ciliary muscle.
- Cardiovascular: Ethanolic extract dilated coronaries and raised coronary flow; total alkaloids antagonized pituitrin ECG changes; dehydrocorydaline protected against isoproterenol myocardial necrosis and hypoxia; a water-insoluble alkaloid fraction was antiarrhythmic in rats.
- Antiulcer and antisecretory: Dehydrocorydaline reduced gastric secretion, pepsin output and ulceration from stress and drugs in rats and antagonized histamine-induced secretion in dogs.
- Pituitary-adrenocortical: dl-THP caused thymic atrophy and adrenal vitamin C reduction in rodents, apparently via hypothalamus.
Source: Zhu YP. Chinese Materia Medica: Chemistry, Pharmacology and Applications. Harwood Academic, 1998, p. 445.
Relationships
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Botanical Description
Corydalis yanhusuo (Y.H.Chou & Chun C.Hsu) W.T.Wang ex Z.Y.Su & C.Y.Wu (Papaveraceae) is a small perennial herb 10-30 cm tall endemic to eastern China, with finely divided ternately compound bluish-green leaves and short racemes of pink to purplish-rose tubular spurred flowers in spring. From the base of the stem it forms a small subglobose to flattened-globose yellow tuberous rhizome 1-2.5 cm in diameter. For Yan Hu Suo, the tubers are dug after the aerial parts wither in early summer, boiled briefly until the centers turn yellow, dried, and often dry-fried with vinegar before use. In TCM, Yan Hu Suo is acrid and bitter in flavor and warm in nature, entering the Heart, Liver, Spleen, and Lung channels; it invigorates blood, moves qi, and is one of the strongest analgesic herbs for many pain patterns.
Active Constituents
Levo-tetrahydropalmatine
Tetrahydroprotoberberine isoquinoline alkaloidConcentration: highly variable; total alkaloid content of a rhizome extract measured about 12.7 mg/g, while 14 commercial supplements ranged from below the limit of quantification to roughly 11 mg/g
The principal sedative and analgesic alkaloid of the drug, acting as an antagonist at dopamine D1 and D2 receptors rather than at opioid receptors. It is also the compound responsible for the hepatitis reported with levo-tetrahydropalmatine-containing herbal products, so it carries both the benefit and the main toxicity of the herb.
Dehydrocorybulbine
Quaternary protoberberine alkaloidIdentified by activity-guided fractionation as the constituent effective against inflammatory and injury-induced neuropathic pain in rodents. Its antinociception depends on inhibitory activity at the dopamine D2 receptor and, unlike opioids, did not produce antinociceptive tolerance on repeated dosing.
Corydaline
Tetrahydroprotoberberine isoquinoline alkaloidOne of eight alkaloids from this species confirmed as dopamine D1 receptor antagonists in a CRE-luciferase reporter assay. It contributes to the antispasmodic and gastric effects attributed to the herb.
Dehydrocorydaline
Quaternary protoberberine alkaloidAn abundant quaternary alkaloid of the tuber with D1 antagonist activity and analgesic and cardiovascular actions in animal models.
Protopine
Protopine-type isoquinoline alkaloidA widely distributed Papaveraceae alkaloid present in the tuber; its content rises or falls with cultivation and rotation practice and it is used alongside tetrahydropalmatine as a quality indicator.
Palmatine and columbamine
Quaternary protoberberine alkaloidsBoth were among the alkaloids shown to antagonise the dopamine D1 receptor. They are also common in Berberidaceae and Menispermaceae drugs, so their presence alone does not authenticate Corydalis yanhusuo.
⚠ Drug Interactions
Hepatotoxic drugs and pre-existing liver disease (paracetamol, methotrexate, isoniazid)
Seven patients taking the herbal product Jin Bu Huan developed acute hepatitis after a mean of about 20 weeks, with a hepatocellular enzyme pattern resembling acute viral hepatitis, hepatomegaly and jaundice, resolving over a mean of eight weeks after withdrawal; a chronic hepatitis case was later reported. The product was labelled as a Polygala species but in fact delivered levo-tetrahydropalmatine, most likely from a Stephania species, so the offending molecule is the same one that Corydalis yanhusuo supplies. The mechanism is undefined and may be idiosyncratic or metabolite-mediated. Attribution of the whole hazard to Corydalis yanhusuo is therefore an inference from shared chemistry, not a direct series on this species, but it is the reason liver monitoring belongs on this herb.
Clinical note: Do not prescribe long courses without baseline and follow-up liver enzymes, and stop at once for nausea, fatigue, pruritus, right upper quadrant pain or jaundice. Avoid stacking with other hepatotoxic drugs or in established liver disease.
Antipsychotics and other dopamine antagonists (haloperidol, risperidone, metoclopramide)
The pharmacology of this herb is largely dopaminergic antagonism, not opioid agonism. Eight alkaloids from Corydalis yanhusuo, including tetrahydropalmatine, corydaline, dehydrocorybulbine, dehydrocorydaline, palmatine and columbamine, were confirmed as dopamine D1 receptor antagonists, and the analgesic action of dehydrocorybulbine is mediated through D2 inhibition. Adding a dopamine-blocking drug on top is pharmacodynamically additive.
Clinical note: Use cautiously in patients on antipsychotics or prokinetics and ask specifically about restlessness, stiffness or tremor. The same logic makes the herb a poor choice for a patient with Parkinson's disease on levodopa or a dopamine agonist, where it may blunt the drug.
CNS depressants (benzodiazepines, z-drugs, opioids, alcohol)
Tetrahydropalmatine is a sedative-hypnotic in its own right, and acute overdose of levo-tetrahydropalmatine-containing products in children produced rapid, life-threatening neurological and cardiovascular depression. Combining the herb with any CNS depressant is therefore expected to be additive.
Clinical note: Warn patients about driving and machinery, especially in the first week. Keep the powdered herb and any concentrated extract out of reach of children, where a single acute ingestion is the dangerous scenario.
Morphine and other opioid analgesics
In rodents the whole extract increased the efficacy of morphine antinociception, so less opioid was needed, and co-administration inhibited morphine tolerance, dependence and addiction, and partially reversed established dependence. This is a potentially useful interaction rather than a purely harmful one, but it is animal data and it means the effective opioid exposure changes when the herb is started or stopped.
Clinical note: If a patient on chronic opioids starts or stops Yan Hu Suo, review the opioid dose and watch for sedation on starting and for breakthrough pain on stopping. Do not present the herb to a patient as a proven opioid-sparing treatment; no human trial has tested that.
Stephania species supplying levo-tetrahydropalmatine (as substituted or adulterating material)
Analysis of 14 Corydalis yanhusuo products sold in the United States found total alkaloid content ranging from below quantifiable to about 11 mg/g. Only five products matched the alkaloid content of an extract made from authentic rhizome, and one was so enriched in tetrahydropalmatine, at roughly 5 mg/g, that the authors concluded it had been adulterated with the isolated compound and flagged the toxicological liability. The Jin Bu Huan hepatitis cases arose from exactly this pattern of a product whose declared botanical identity did not match the alkaloid it delivered.
Clinical note: Buy on a certificate of analysis that quantifies the alkaloid profile, not just tetrahydropalmatine, and be sceptical of any product whose tetrahydropalmatine content is far above what a rhizome extract can deliver.
Calcium channel blockers and negative inotropes
Corydalis yanhusuo total alkaloids inhibited the L-type calcium current, cell contraction and the calcium transient in isolated rat cardiomyocytes under patch clamp and IonOptix measurement. No human cardiovascular interaction study exists; the concern is extrapolated from that isolated-cell electrophysiology.
Clinical note: Reasonable caution in patients with reduced ejection fraction already on rate- or contractility-limiting drugs; no monitoring protocol is established.
Dosage
| Form | Amount | Frequency | Duration | Population | Notes |
|---|---|---|---|---|---|
| decoction, or powder/pills | 3–10 g | Daily | — | — | 中国药典 2020 monograph 【延胡索（元胡）】【用法与用量】3～10g；研末吞服，一次1.5～3g。 【性味与归经】辛、苦，温。归肝、脾经。 — Matched by hand: Identical drug; ChP simply prints the 元胡 alias in the monograph title. Chinese Pharmacopoeia 2020, quoted verbatim. |
Dui Yao — Herb Pairs
The classical two-herb combinations this herb appears in, each with an action neither herb has alone.
Together they spread constrained Liver qi, drain Liver heat and move blood, giving a strong analgesic effect for pain from qi stagnation transforming into heat.
Hypochondriac, epigastric, hernial and menstrual pain from Liver qi stagnation with heat. Chuan Lian Zi is mildly toxic.
Core pair of a classical formula — Jin Ling Zi San, Tai Ping Sheng Hui Fang (recorded in Xiu Zhen Fang)
Evidence Tier
Moderate evidence · 5 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
0
Other clinical trial
1
1 verified · 0 unverified
Observational / case report
0
In vitro / animal
4
1 verified · 3 unverified
Show 4 studies
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
Effects of Corydalis yanhusuo and Angelicae dahuricae on Cold Pressor-Induced Pain in Humans: A Controlled Trial
Using the cold-pressor test for tonic pain, a single oral dose of extracts of Corydalis yanhusuo and Angelica dahurica significantly reduced pain intensity and pain bothersomeness scores, both p less than 0.01, with a dose-related effect. This is one of the few human analgesia datasets for the herb, but it tested the two-herb pair rather than Corydalis yanhusuo alone, so the contribution of each species cannot be separated.
A Novel Analgesic Isolated from a Traditional Chinese Medicine
Activity-guided fractionation of Corydalis yanhusuo identified dehydrocorybulbine as the compound relieving thermally induced acute pain, and it was also effective against inflammatory and injury-induced neuropathic pain in rodents. Its antinociception depended on dopamine D2 receptor inhibition and, in contrast to opioids, produced no antinociceptive tolerance.
The Antinociceptive Properties of the Corydalis yanhusuo Extract
The whole extract of Corydalis yanhusuo produced antinociception across acute, inflammatory and neuropathic pain models in rodents, and the effect was attributed substantially to antagonism at dopamine receptors rather than to opioid receptor activity.
The Extract of Corydalis yanhusuo Prevents Morphine Tolerance and Dependence
In rodents the extract increased the efficacy of morphine antinociception, and when co-administered it inhibited morphine tolerance, dependence and addiction; in animals already treated with morphine for several days it partially reversed dependence and addiction. The authors attribute the effect at least in part to dopamine D2 receptor inhibition.
Large variability in the alkaloid content of Corydalis yanhusuo dietary supplements
Nineteen alkaloids were quantified by HPLC with diode array detection in 14 Corydalis yanhusuo products covering most of what is sold online in the United States. Total alkaloid content ranged from below quantifiable to about 11 mg/g; five products matched the roughly 12.7 mg/g of an extract prepared from the rhizome, others held about 1.8 mg/g, and one was so enriched in tetrahydropalmatine, near 5 mg/g, that the authors judged it adulterated with the isolated compound and raised a toxicological concern.
⚠ Safety & Contraindications
- Pregnancy
- Young children
- Liver conditions
Contraindications
Its use is prohibited in pregnant women and patients with blood heat and qi deficiency.
Source: Xi S, Gong Y. Essentials of Chinese Materia Medica and Medical Formulas. Academic Press/Elsevier, 2017, pp. 230–235.
Side Effects
- dl-THP does not significantly affect liver/renal function, blood pressure or heart rate
- At therapeutic doses may cause vertigo, fatigue and occasional nausea
- In monkeys, oral dl-THP 180 mg/kg caused transient stimulation then severe depression, sedation, deep hypnosis, parkinsonian limb tremor and urinary casts, reversible in a few days; 85 mg/kg daily for 2 weeks caused similar reactions (without sedation/hypnosis) and mild cloudy swelling of heart and kidney
- Single oral 85 or 100 mg/kg or s.c. 80 mg/kg dl-THP in monkeys produced no significant toxicity
Source: Zhu YP. Chinese Materia Medica: Chemistry, Pharmacology and Applications. Harwood Academic, 1998, p. 445.
Historical Texts
Ben Cao Shi Yi
Tang dynasty, 739Ben Cao Gang Mu
Ming dynasty, 1596References
- Woolf GM, Petrovic LM, Rojter SE, Wainwright S, Villamil FG, Katkov WN, Michieletti P, Wanless IR, Stermitz FR, Beck JJ, Vierling JM. Acute Hepatitis Associated with the Chinese Herbal Product Jin Bu Huan . Annals of Internal Medicine (1994) [DOI]
- Alhassen L, Dabbous T, Ha A, Dang LHL, Civelli O. The Analgesic Properties of Corydalis yanhusuo . Molecules (2021) [DOI]
- Wu L, Yang Y, Mao Z, Wu J, Ren D, Zhu B, Qin L. Processing and Compatibility of Corydalis yanhusuo: Phytochemistry, Pharmacology, Pharmacokinetics, and Safety . Evidence-Based Complementary and Alternative Medicine (2021) [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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