Reviewed August 2026 by the Corydalis Labs Technical Team. How we research and review.
The plant
Corydalis yanhusuo is a perennial in the Papaveraceae — the poppy family. It grows from a small tuberous rhizome, which is the part harvested, dried, and used. In classical Chinese materia medica the material is called yan hu suo; you will also see the plant referred to as Corydalis turtschaninovii and the material as Rhizoma Corydalis.
It has been cultivated and traded as a herbal material for a very long time, which is worth stating clearly: this is not a newly discovered organism, and its constituents are not novel chemistry. That history is part of why the compound sits where it does regulatorily.
What is in the rhizome
The rhizome contains a complex mixture of isoquinoline alkaloids. The best characterised and most abundant is tetrahydropalmatine (THP). Others reported in the literature include corydaline, protopine, dehydrocorybulbine (DHCB), and palmatine.
You will encounter suppliers and articles that name different alkaloids as the "primary active" — most often THP or DHCB. Both appear in the plant and both are discussed in the literature; which one is emphasised often reflects what a given product is standardised to rather than a settled scientific claim. We standardise our material on 13-OH and report it on the certificate of analysis, so there is no ambiguity about what you are buying. Our testing programme.
Extract is not the same as isolate
"Corydalis extract" can mean anything from a lightly concentrated whole-rhizome preparation to a standardised single-alkaloid isolate. The word alone tells you nothing about potency or composition — the certificate of analysis does. This matters when comparing suppliers, because two materials with identical names can differ enormously.
The traditional record
Yan hu suo appears in classical Chinese materia medica and has been used in traditional preparations for centuries, typically decocted or powdered. We reference this because it is historically accurate and because it speaks to the plant's long human association — not as evidence of any particular effect in a modern product.
Traditional use is a fact about history, not a health claim, and we are careful not to blur those. Nothing on this site is intended to suggest that 13-OH or any product containing it diagnoses, treats, cures, or prevents any condition.
Why the plant matters to the compound
Two reasons, one scientific and one regulatory.
Scientifically, the botanical origin means 13-OH is a derivative of a naturally occurring plant alkaloid rather than a molecule designed from scratch. That is a genuinely different provenance from compounds built to resemble something already controlled.
Regulatorily, neither the plant, nor its extract, nor its principal alkaloid appears on the federal controlled substance schedules or the DEA List I/II chemical lists. Because the salts-and-isomers principle extends control only where a parent is scheduled, there is nothing here for a derivative rule to attach to. The regulatory summary sets this out with the primary sources.
Sourcing and consistency
Botanical raw material varies — with cultivar, growing conditions, harvest timing, and processing. That variability is exactly why a finished ingredient needs to be standardised and tested rather than sold on the strength of its plant name.
Our material is standardised and assayed lot by lot, typically running 93–98% active, and every lot ships with a certificate of analysis. If you are comparing suppliers, the certificate is the only meaningful basis for comparison. What we test and what you receive.
Common questions
Corydalis rhizome and its extract do not appear on the federal controlled substance schedules or the DEA List I/II chemical lists as of August 2026. That is a statement about controlled-substance status specifically; how a finished product may be formulated, labelled, and marketed involves separate rules. Review both with your own counsel. Regulatory summary.
No. Corydalis yanhusuo is in the poppy family, Papaveraceae. Kratom is Mitragyna speciosa, in the coffee family, Rubiaceae. They are unrelated plants with unrelated alkaloid chemistry.
Dehydrocorybulbine, another alkaloid reported in Corydalis rhizome. It is a different compound from tetrahydropalmatine. Some sources name DHCB as the plant’s primary active and others name THP; both are present, and which is emphasised usually depends on what a particular product is standardised to. Both are defined in the glossary.
No, and we would not claim that. A long history of traditional use is a historical fact. It is not a substitute for modern safety or efficacy data, and it does not support any health claim about a finished product.