Corydalis (yan hu suo)

• Three different products, three risk pictures. Whole corydalis tuber, the Yuanhu Zhitong formula and purified l-THP (rotundine) are not the same. Most hard safety data (poisoning, hospital series, drug trials) are for purified l-THP or for look-alike products. Whole-herb data are two liver case reports, reviews and animal studies. Do not assume the safety of one applies to another. Authoritative guidance ^{17 5 6 14}
• Liver injury has been reported. Two adults developed probable drug-induced liver injury after a corydalis-containing sleep aid; liver tests improved after stopping and rose again on re-use in one. Reports of liver injury also exist for Jin Bu Huan tablets, which contain l-THP. Case series ^{6 18 11 12}
• Sedation and driving. The most common effects are drowsiness and dizziness. WebMD advises not to drive or do tasks needing alertness until you know how it affects you. In overdose of l-THP, central nervous system depression was the main finding. Authoritative guidance ^{17 5}
• Heart rhythm and blood pressure. WebMD lists heart rhythm changes and fainting as serious but less common effects and advises telling a doctor about heart rhythm problems. In overdose, 16.2% of 37 patients had a prolonged QTc. Reviews say the alkaloids lowered blood pressure in animals. A 3.5-day human trial of l-THP showed no blood pressure or ECG difference. Mixed ^{17 5 19 4 10}
• Pregnancy, breastfeeding and children. Avoid in pregnancy and breastfeeding: effects are unknown and it may affect menstrual flow. Children who swallowed Jin Bu Huan (which contains l-THP) developed life-threatening nerve and heart effects. Case series ^{17 11}
• Product quality is unreliable. In a 2024 analysis of 14 US corydalis supplements, alkaloid content ranged from none measurable to about 11 mg/g, and one product had far more THP than expected, suggesting added isolated compound. Laboratory research ^{13 3}

Two adults developed probable drug-induced liver injury after using a cannabis-dispensary sleep aid that listed corydalis as an active ingredient: one woman without symptoms had liver enzymes rise and fall with use and re-use, and one man with symptoms recovered after stopping. The product may have had other ingredients. Separately, Jin Bu Huan Anodyne Tablets (sold as Lycopodium serratum but found to contain l-THP) were linked to acute hepatitis in seven adults after about 20 weeks of use, with relapse on re-use in two, and to nerve and heart poisoning in children. LiverTox's Jin Bu Huan summary says more than a dozen liver injury cases were reported but that the cause was likely a contaminant; a LiverTox entry for corydalis itself could not be confirmed. WebMD lists liver damage as a reported effect. In animals, high amounts of raw extract caused liver damage, and vinegar processing reduced it. ^{6 18 11 12 17 19}

How often. No frequency can be given. The corydalis cases are two; reports of related products are about a dozen. Not finding more cases is not proof of safety.

Monitoring. No agency monitoring advice was found. Stop and get medical help for yellow skin or eyes, dark urine, pale stools, severe itching, or unusual tiredness and nausea. People with liver disease should ask a doctor before use.

• . Two adults; probable corydalis sleep-aid liver injury; improved on stopping; rechallenge positive in one ⁶
• . Seven adults; Jin Bu Huan hepatitis; six recovered, two relapsed on re-use (product not corydalis; l-THP content reported later) ¹⁸

This is a safety connection. It is not evidence that Corydalis (yan hu suo) supports liver health.

Summary. Human poisoning data are for purified l-THP (rotundine) and Jin Bu Huan, not whole tuber. Reviews say toxicity studies of THP are limited.

Animal. Raw extract at high amounts caused mild liver toxicity, muscle tremor, spasms, convulsions and kidney bleeding in mice and rats; vinegar processing and combining with other herbs reduced toxicity. The toxic alkaloids are not identified (Wu 2021).

Human doses studied. A 3.5-day course of isolated l-THP in 24 men was well tolerated. No dose claims are made here.

High dose or long term signals. Hepatitis after prolonged use of Jin Bu Huan (l-THP) in adults; liver injury with a corydalis sleep aid.

Overdose response. In 37 Vietnamese patients with acute rotundine poisoning: CNS depression, QTc prolongation in 16.2%, 10.8% needed a ventilator, no deaths.

Genotoxicity. Not found in the sources read.

Toxic plant parts. The dried tuber is the medicinal part. Raw (unprocessed) tuber extract was more toxic than vinegar-processed in animals. Other parts are not described as medicine.

Quality is a real problem: alkaloid content varies enormously and some products may contain added purified THP. THP also occurs naturally in other plants such as Stephania, so look-alike or adulterated products are possible.

Wide variation in strength. In 14 US supplements, total alkaloids ranged from below measurable to about 11 mg/g; five matched a lab extract, the others were far weaker. ¹³

Possible added purified THP. One of the 14 products had about 5 mg/g THP, which the authors say suggests adulteration with the isolated compound. ¹³

Undeclared THP in a patent medicine. Hong Kong's Department of Health ordered a recall of Sci-tica Herbal Pills in 2009 after finding undeclared THP. ³

Mislabelled Jin Bu Huan. The package misnamed the ingredients, which delayed finding l-THP as the cause of poisoning. ¹¹

Other plants with THP (Stephania, Corydalis species). THP is found in Stephania and several Corydalis species as well as C. yanhusuo, so a product's THP may come from another plant. No source we read documents substitution of Stephania or other Corydalis species in yan hu suo products. ⁴

• Yellow skin or eyes, dark urine, pale stools, severe itching, or nausea with tiredness (possible liver injury).
• Fainting, chest pain, a very slow, fast or irregular heartbeat.
• Hard to wake, confusion, slow breathing or collapse (especially after a large amount or in a child).
• Swelling of the face or throat, hives or trouble breathing (allergy).

Stop the supplement and contact a clinician or emergency service. In the US, Poison Control is 1-800-222-1222.