Corydalis

In Traditional Chinese Medicine, corydalis (yan hu suo) is considered acrid, bitter and warm.

It is used to invigorate the blood, move qi and relieve pain. It is regarded as one of the more versatile pain-relieving herbs of the tradition, and it is used for pain anywhere in the body.

Traditional indications include menstrual pain, chest pain, abdominal pain, injury, headache, hernia pain and rheumatic pain. It is especially associated with fixed, sharp pain from stagnation.

Western herbalists use corydalis as a pain reliever and mild sedative.

It is used for chronic musculoskeletal pain, rheumatoid arthritis, nerve pain, menstrual pain and tension-related pain.

It is often combined with California poppy, Jamaican dogwood, cramp bark and valerian in formulas for pain.

Pain relief is the most studied activity of corydalis, almost all of it in animals. A 2014 Current Biology study screened the tuber and isolated dehydrocorybulbine (DHCB), a moderate dopamine-receptor antagonist. It relieved acute thermal, inflammatory and injury-induced neuropathic pain in mice, mainly through D2 receptors, without producing tolerance ^{1Reference 1Zhang Y et al et al. · 2014AnimalA novel analgesic isolated from a traditional Chinese medicine — animal model, in vivoView study →}.

A follow-up tested a whole Corydalis yanhusuo extract in acute, inflammatory and chronic neuropathic pain assays and found pain relief at non-sedative doses, again without tolerance ^{2Reference 2Wang L et al et al. · 2016AnimalThe Antinociceptive Properties of the Corydalis yanhusuo Extract — animal model, knock-out miceView study →}.

The main tuber alkaloids (tetrahydropalmatine, corydaline, protopine and dehydrocorydaline) all inhibit the Nav1.7 sodium channel ^{3Reference 3Xu Y et al et al. · 2021In vitroAnalgesic effect of the main components of Corydalis yanhusuo (yanhusuo in Chinese) is caused by inhibition of voltage gated sodium channels — in vivo, in vitroView study →}.

Dehydrocorydaline’s pain relief in inflammatory pain was blocked by naloxone, implicating opioid receptors, and it lowered spinal TNF-α, IL-1β and IL-6 ^{4Reference 4Yin ZY et al et al. · 2016AnimalAntinociceptive effects of dehydrocorydaline in mouse models of inflammatory pain involve the opioid receptor and inflammatory cytokines — mouse, in vivoView study →}. It also reduced spinal neuroinflammation in bone-cancer and nerve-injury pain models, shifting microglia towards the anti-inflammatory M2 type ^{5,6,9Reference 5Huo W et al et al. · 2018AnimalDehydrocorydaline attenuates bone cancer pain by shifting microglial M1/M2 polarization toward the M2 phenotype — mouse model, in vivoView study →Reference 6Hou BL et al et al. · 2025AnimalAnalgesic Effect of Dehydrocorydaline on Chronic Constriction Injury-Induced Neuropathic Pain via Alleviating Neuroinflammation — mouse, in vivoView study →Reference 9Dehghani M et al et al. · 2025ReviewEXPRESS: Dehydrocorydaline can be a suitable candidate for analgesic purposes: a review on the current preclinical evidence — reviewView study →}.

L-THP relieved neuropathic pain in rats through the Clec7a–NF-κB–NLRP3 inflammasome pathway ^{7Reference 7Wu D et al et al. · 2023AnimalLevo-tetrahydropalmatine ameliorates neuropathic pain by inhibiting the activation of the Clec7a-MAPK/NF-κB-NLRP3 inflammasome axis — rat, in vivoView study →}.

In a rat model of trigeminal nerve pain, the effect of dl-THP was blocked by a CB1 cannabinoid-receptor antagonist ^{8Reference 8Huang JY et al et al. · 2010AnimalHuang JY et al. (2010). [Analgesic effect of Corydalis yanhusuo in a rat model of trigeminal neuropathic pain] — rat model, in vivo. Nan Fang Yi Ke Da Xue Xue Bao. https://pubmed.ncbi.nlm.nih.gov/20855279/View study →}. L-THP itself has been used for decades to relieve chronic pain ^{7Reference 7Wu D et al et al. · 2023AnimalLevo-tetrahydropalmatine ameliorates neuropathic pain by inhibiting the activation of the Clec7a-MAPK/NF-κB-NLRP3 inflammasome axis — rat, in vivoView study →}.

Gap: No placebo-controlled trial has tested the whole tuber for a defined pain condition. Human experience comes from clinical use of isolated l-THP.

The human trials of corydalis alkaloids are of tetrahydropalmatine in its levo form (l-THP), which blocks dopamine D1 and D2 receptors and interacts with D3 receptors ^{13Reference 13Mantsch JR et al et al. · 2007AnimalLevo-tetrahydropalmatine attenuates cocaine self-administration and cocaine-induced reinstatement in rats — rat, in vivoView study →}.

In a randomised, double-blind, placebo-controlled pilot trial in 120 heroin-dependent patients, four weeks of l-THP reduced withdrawal symptoms and craving. Among patients who stayed in the programme, the three-month abstinence rate was 47.8% on l-THP against 15.2% on placebo ^{10Reference 10Yang Z et al et al. · 2008RCTMedication of l-tetrahydropalmatine significantly ameliorates opiate craving and increases the abstinence rate in heroin users: a pilot study — randomised, double-blind, placebo-controlledView study →}.

In a randomised, double-blind, placebo-controlled study in 24 men who used cocaine, oral l-THP (30 mg twice daily for four days) was safe and well tolerated and did not change cocaine’s blood levels or its effects on the heart ^{11Reference 11Hassan HE et al et al. · 2017RCTPharmacokinetics and Safety Assessment of l-Tetrahydropalmatine in Cocaine Users: A Randomized, Double-Blind, Placebo-Controlled Study — randomised, double-blind, placebo-controlledView study →}.

These small trials sit on a consistent rodent literature. L-THP reduced self-administration and relapse-like reinstatement for cocaine ^{12,13Reference 12Figueroa-Guzman Y et al et al. · 2011AnimalOral administration of levo-tetrahydropalmatine attenuates reinstatement of extinguished cocaine seeking by cocaine, stress or drug-associated cues in rats — rat, in vivoView study →Reference 13Mantsch JR et al et al. · 2007AnimalLevo-tetrahydropalmatine attenuates cocaine self-administration and cocaine-induced reinstatement in rats — rat, in vivoView study →}, heroin ^{14Reference 14Yue K et al et al. · 2012AnimalThe dopamine receptor antagonist levo-tetrahydropalmatine attenuates heroin self-administration and heroin-induced reinstatement in rats — rat, in vivoView study →}, nicotine ^{15Reference 15Faison SL et al et al. · 2016Animall-tetrahydropalmatine reduces nicotine self-administration and reinstatement in rats — rat, in vivoView study →} and methamphetamine ^{17,18,19Reference 17Liu L et al et al. · 2021ReviewLevo-tetrahydropalmatine: A new potential medication for methamphetamine addiction and neurotoxicity — reviewView study →Reference 18Gong X et al et al. · 2016AnimalLevo-tetrahydropalmatine, a natural, mixed dopamine receptor antagonist, inhibits methamphetamine self-administration and methamphetamine-induced reinstatement — rat, in vivoView study →Reference 19Su H et al et al. · 2020AnimalLevo-tetrahydropalmatine attenuates methamphetamine reward behavior and the accompanying activation of ERK phosphorylation in mice — mouse, in vivoView study →}, and a combination with low-dose naltrexone worked better than l-THP alone for cocaine relapse ^{16Reference 16Sushchyk S et al et al. · 2016AnimalCombination of Levo-Tetrahydropalmatine and Low Dose Naltrexone: A Promising Treatment for Prevention of Cocaine Relapse — rat, in vivoView study →}.

Gap: The human evidence is for a purified single alkaloid, l-THP, not the herb. The tuber has never been trialled for addiction, and the two trials are small.

Corydalis extracts suppress inflammatory signalling, and the activity has been traced to a specific alkaloid. In cultured macrophages stimulated with LPS, dehydrocorydaline, which made up more than half of the extract’s alkaloids, accounted for most of the anti-inflammatory effect ^{20Reference 20Kong X et al et al. · 2020In vitroDehydrocorydaline Accounts the Majority of Anti-Inflammatory Property of Corydalis Rhizoma in Cultured Macrophage — in vitroView study →}.

Newly isolated seco-protoberberines from C. yanhusuo suppressed nitric oxide in the same macrophage system ^{21Reference 21Xia GY et al et al. · 2022In vitroXia GY et al. (2022). 13,13a-seco-protoberberines from the tubers of Corydalis yanhusuo and their anti-inflammatory activity — in vitro. Phytochemistry. https://pubmed.ncbi.nlm.nih.gov/34839130/View study →}. In a collagen-induced arthritis model in rats, a related species, C. decumbens, and its alkaloid reduced macrophage inflammation through the transcription factor Fosl2 ^{22Reference 22Gao P et al et al. · 2025In vitroCorydalis decumbens and tetrahydropalmatrubin inhibit macrophages inflammation to relieve rheumatoid arthritis by targeting Fosl2 — rat, in vivo, in vitroView study →}.

In a diet-induced fatty-liver model, tetrahydropalmatine reduced liver fat by shifting lipid metabolism through the AMPK–SREBP-1c–Sirt1 pathway ^{34Reference 34Yin X et al et al. · 2023In vitroTetrahydropalmatine ameliorates hepatic steatosis in nonalcoholic fatty liver disease by switching lipid metabolism via AMPK-SREBP-1c-Sirt1 signaling axis — in vitro, in vivoView study →}.

The strongest data are in vitro, use a different Corydalis species, or rest on an isolated alkaloid in a rodent model. No human anti-inflammatory trial exists.

In a rat model of single prolonged stress (a PTSD model), daily l-THP had anxiety-reducing and antidepressant-like effects in the elevated-plus-maze, open-field and forced-swim tests ^{23Reference 23Lee B et al et al. · 2014AnimalL-tetrahydropalmatine ameliorates development of anxiety and depression-related symptoms induced by single prolonged stress in rats — rat, in vivoView study →}.

Dehydrocorydaline had antidepressant-like effects in a chronic mild stress model in mice, apparently by blocking uptake-2 monoamine transporters and raising brain monoamine levels ^{24Reference 24Jin L et al et al. · 2019AnimalDehydrocorydaline induced antidepressant-like effect in a chronic unpredictable mild stress mouse model via inhibiting uptake-2 monoamine transporters — mouse, in vivoView study →}.

Gap: The sedative activity behind this indication is also corydalis’s main interaction hazard, since it adds to alcohol, benzodiazepines, opioids and other sedatives. The behavioural evidence is entirely from animals.

A scattered set of studies reports neuroprotection across very different injuries. Tetrahydropalmatine reduced neuronal injury, overheating and brain ischaemia in a rat heatstroke model ^{26Reference 26Chang CK et al et al. · 1999AnimalThe neuroprotective effect of DL-tetrahydropalmatine in rat heatstroke — rat, in vivoView study →}, and lowered death rates and brain inflammation in mice infected with Japanese encephalitis virus ^{25Reference 25Lixia H et al et al. · 2018AnimalNeuroprotective effect of (-)-tetrahydropalmatine in Japanese encephalitis virus strain GP-78 infected mouse model — mouse, in vivoView study →}.

In rat brain nerve terminals, dehydrocorydaline inhibited glutamate release ^{27Reference 27Lin TY et al et al. · 2022In vitroInhibition of Glutamate Release from Rat Cortical Nerve Terminals by Dehydrocorydaline, an Alkaloid from — in vitroView study →}.

The models are varied, and none maps onto a human neurological condition.

In anaesthetised rats, intravenous dl-tetrahydropalmatine lowered blood pressure and slowed the heart through central dopamine-D2 and 5-HT2 antagonism ^{28,29Reference 28Lin MT et al et al. · 1996AnimalAntihypertensive effects of DL-tetrahydropalmatine: an active principle isolated from Corydalis — rat, in vivoView study →Reference 29Chueh FY et al et al. · 1995AnimalDL-tetrahydropalmatine-produced hypotension and bradycardia in rats through the inhibition of central nervous dopaminergic mechanisms — rat, in vivoView study →}. A separate rat study reported protection of the heart after acute myocardial infarction ^{30Reference 30Han BJ et al et al. · 2022AnimalCardioprotective Effects of Tetrahydropalmatine on Acute Myocardial Infarction in Rats — rat, in vivoView study →}.

Gap: Lowering blood pressure and slowing the heart is a safety signal as much as a benefit, particularly alongside blood-pressure medicines or in anyone prone to low blood pressure. All of the data are from animals.

Dehydrocorydaline inhibited the growth of MCF-7 breast-cancer cells by inducing caspase-dependent apoptosis ^{31Reference 31Xu Z et al et al. · 2012In vitroDehydrocorydaline inhibits breast cancer cells proliferation by inducing apoptosis in MCF-7 cells — in vitroView study →}. It also reduced the growth, spread and survival of the more aggressive MDA-MB-231 breast-cancer cells, and slowed the growth of these tumours grafted into mice ^{32Reference 32Huang Y et al et al. · 2020In vitroDehydrocorydaline inhibits the tumorigenesis of breast cancer MDA‑MB‑231 cells — in vitroView study →}.

The evidence is for one compound, in cells and one mouse model, with no human data.

A C. yanhusuo extract showed activity against Helicobacter pylori in vitro and protected the stomach in infected mice. Dehydrocorydaline and berberine were among its active alkaloids ^{33Reference 33Wu H et al et al. · 2023In vitroGastroprotective action of the extract of Corydalis yanhusuo in Helicobacter pylori infection and its bioactive component, dehydrocorydaline — in vitro, in vivoView study →}.

This is a single extract study in cells and mice, with no clinical confirmation.

Sedation. Tetrahydropalmatine blocks dopamine receptors and is sedating, so corydalis adds to the effect of sedatives, sleep medicines, alcohol and other CNS depressants.

Blood pressure and heart. In rats, tetrahydropalmatine lowers blood pressure and slows the heart through central dopamine mechanisms ^{28,29Reference 28Lin MT et al et al. · 1996AnimalAntihypertensive effects of DL-tetrahydropalmatine: an active principle isolated from Corydalis — rat, in vivoView study →Reference 29Chueh FY et al et al. · 1995AnimalDL-tetrahydropalmatine-produced hypotension and bradycardia in rats through the inhibition of central nervous dopaminergic mechanisms — rat, in vivoView study →}. This calls for care in people with low blood pressure or a slow heart rate, or on blood-pressure or heart medicines. In animal tests, the minor alkaloid protopine raised the heart-muscle enzyme CK-MB and affected the heart’s Nav1.5 sodium channel ^{3Reference 3Xu Y et al et al. · 2021In vitroAnalgesic effect of the main components of Corydalis yanhusuo (yanhusuo in Chinese) is caused by inhibition of voltage gated sodium channels — in vivo, in vitroView study →}.

Liver. Jin Bu Huan is a concentrated Chinese patent medicine whose neuroactive alkaloid is l-THP; its ingredients were misidentified on the package. Long-term use in adults caused hepatitis, and a single overdose in children caused life-threatening effects on the nervous system and heart ^{36Reference 36Horowitz RS et al et al. · 1996Case reportThe clinical spectrum of Jin Bu Huan toxicity — case reportsView study →}. Corydalis is best avoided in liver disease.

Interactions. In cocaine users, oral l-THP did not change cocaine’s blood levels ^{11Reference 11Hassan HE et al et al. · 2017RCTPharmacokinetics and Safety Assessment of l-Tetrahydropalmatine in Cocaine Users: A Randomized, Double-Blind, Placebo-Controlled Study — randomised, double-blind, placebo-controlledView study →}. No human CYP450 interaction study has been done.

Anyone taking prescription pain, sedative or neurological medicines should consult a qualified practitioner before use.