Yuan Hua (Genkwa Flower)

Chinese Herb Actions

Chinese Herb Dosage

• What is the dosage of Yuan Hua?

  No dose figure is published on this page. Yuan Hua is a toxic drastic purgative whose active constituents are daphnane diterpene orthoesters — among the more powerfully irritant classes of plant compound known. In rats, three times the maximum dose specified in the Chinese Pharmacopoeia produced damage to heart, liver, kidney and testis. That is not a margin that a printed number on a reference page can responsibly represent.

  • Where it belongs, if anywhere. Harsh expellants are practitioner-only medicinals, dispensed inside prepared classical formulas by someone qualified to supervise them. They have no role in self-administration and none in casual experimentation.
  • Processing does not make it a benign herb. Laboratory work has measured the difference between crude and vinegar-processed material, and a 13-week rodent study of processed extract still found raised liver weight and raised serum alkaline phosphatase at higher doses, together with a positive Ames test. We record those findings as toxicology; no processing method is described here.
  • The classical literature agreed. Every traditional source that carries Yuan Hua carries it with warnings attached, and it is one of the herbs named in the Eighteen Incompatibilities — see the notes and cautions sections below.

  Sources: PMID 30339979, DOI 10.1016/j.jep.2018.10.014 (toxicity of heart, liver, kidney and testis in rats at three times the pharmacopoeial maximum dose); PMID 25882305, DOI 10.1016/j.yrtph.2015.04.008 (13-week study of processed Genkwa Flos: increased liver weight, raised alkaline phosphatase, mutagenic in the Ames test); PMID 38906384 (review of toxicity). Reference statement only — not a prescription, preparation or self-use instruction.

Chinese Herb Contraindications & Cautions

• Are there cautions for Yuan Hua?

  Yes, and they are absolute rather than relative. Yuan Hua is flagged toxic in our own record, is contraindicated in pregnancy, and must not be combined with Gan Cao. It belongs to a small class of medicinals that were never routine even in the classical period, and it is not a herb for self-administration under any circumstances.

  • Pregnancy. The dried flowers have a documented historical use as an abortifacient, recorded as such in the pharmacological literature alongside the purgative and diuretic actions. That alone rules the herb out in pregnancy, and it should also be avoided when breastfeeding and in anyone attempting to conceive — rodent work found testicular as well as renal toxicity.
  • Never with licorice. The Gan Cao pairing is recorded in our own data as an incompatibility and is supported by the animal and chemical evidence summarised in the notes section. Because licorice is one of the most widely included herbs in Chinese formulas, this is a practically important restriction rather than a theoretical one.
  • Deficiency and depletion. As with the whole harsh-expellant category, the traditional contraindication extends to weak, depleted or elderly patients, and to anyone whose fluid accumulation arises from deficiency rather than excess — the herb removes fluid violently and takes strength with it.
  • Local irritancy. The daphnane compounds responsible for the plant’s activity are skin and mucous-membrane irritants. Handling raw material carelessly is itself a hazard, quite apart from ingestion.
  • Existing medication. See the interactions section: there is experimental evidence that genkwa alters intestinal drug transport, which matters for anyone taking prescribed medicines.

  Sources: Sacred Lotus herb identity (Toxic) and incompatibility records; PMID 22590685, PMC 3347322, DOI 10.3390/v4040539 (dried flowers documented as an abortifacient with purgative and diuretic activity); PMID 30339979, DOI 10.1016/j.jep.2018.10.014 (renal and reproductive toxicity aggravated in combination with licorice); PMID 38906384, DOI 10.1016/j.fitote.2024.106089 (toxicity overview); PMID 35204693, PMC 8961543, DOI 10.3390/biom12020192 (daphnane diterpene chemistry and associated toxicity). Neutral reference facts, not medical advice.

Chinese Herb Toxicity & Overdose

• Is Yuan Hua toxic, and what makes it toxic?

  Yes — genuinely and specifically. The toxicity of Daphne genkwa comes from daphnane-type diterpenes, in particular the daphnane orthoesters, a compound class whose irritant and tumour-promoting relatives are among the most biologically aggressive substances in the plant kingdom. A 2026 analytical study characterised 37 daphnane diterpenoids in the flowers alone, mainly daphnane orthoesters and polyhydroxy daphnanes.

  • Named compounds. The best-studied are the “yuanhua” series — yuanhuacin (also written yuanhuacine), yuanhuadin, yuanhuafin and seven further analogues. A review of the series notes that while some are studied for anticancer activity, others, specifically yuanhuafin and yuanhuapin, are regarded as more toxic. Structure matters: the orthoester group is directly implicated in the cytotoxicity of these diterpenes.
  • Whole-organism toxicity. A full toxicity assessment in the nematode C. elegans found that raw genkwa exposure shortened lifespan and impaired development, reproduction and locomotion, produced abnormal vulval formation, damaged the development of GABAergic motor neurons, and induced intestinal reactive-oxygen-species production with disrupted intestinal barrier gene expression.
  • Target organs in mammals. Subacute dosing in rats produced toxicity of heart, liver, kidney and testis at three times the pharmacopoeial maximum dose. In intestinal epithelial cells, the dichloromethane fraction was identified as the toxic fraction, depleting glutathione and superoxide dismutase, raising lactate dehydrogenase and malondialdehyde, inhibiting membrane ATPases and driving apoptosis.
  • Genotoxicity signal. A 13-week rodent study of processed genkwa extract, conducted to international test guidelines, reported increased liver weight and raised serum alkaline phosphatase at 667 and 2,000 mg/kg — evidence of hepatotoxic potential — and a positive Ames test indicating mutagenic potential. This is the finding that most argues against treating processed material as simply safe.

  Sources: PMID 42329339, DOI 10.1007/s11418-026-02056-z (37 daphnane diterpenoids characterised in the flowers); PMID 35204693, PMC 8961543, DOI 10.3390/biom12020192 (the yuanhua diterpene series; relative toxicity of analogues); PMID 30406671, DOI 10.1080/14786419.2018.1536133 (orthoester group and cytotoxicity); PMID 24626436, PMC 3953530, DOI 10.1371/journal.pone.0091825 (full toxicity assessment in C. elegans); PMID 30339979, DOI 10.1016/j.jep.2018.10.014 (cardiac, hepatic, renal and testicular toxicity in rats); PMID 29945380, DOI 10.19540/j.cnki.cjcmm.2018.0070 (toxic fraction and oxidative damage in intestinal epithelial cells); PMID 25882305, DOI 10.1016/j.yrtph.2015.04.008 (13-week toxicity and positive Ames test for processed material). Neutral reference facts, not medical advice.

• This herb is considered toxic.
  (while some Chinese herbs are toxic, it must be noted that many come prepared, or are combined, to mitigate their toxicity)

Herb-Drug Interactions

• Does Yuan Hua interact with medications?

  There is experimental evidence that it can. In rats, genkwa decoction significantly increased the absorptive transport of rhodamine 123 — a standard marker substrate for the P-glycoprotein efflux transporter — across jejunum membranes, and the same effect was seen with licorice decoction and with the two given together. P-glycoprotein governs how much of many oral drugs is absorbed and how much is pumped back out of the gut wall, so interference with it is a general mechanism for altered drug levels.

  • Why this matters. Medicines whose absorption depends on P-glycoprotein include several cardiac, immunosuppressant, anticoagulant and antiviral drugs. An effect on that transporter is a plausible route to unintended changes in blood levels.
  • It is also part of the incompatibility story. The same experiment tested licorice and genkwa together, which is the classically prohibited pair — giving a transport-level dimension to a rule that is usually discussed only in terms of toxicity.
  • Scope of the evidence. This is animal-tissue work, not a clinical interaction study. It establishes a mechanism worth respecting, not a quantified human risk.

  Source: PMID 19149264 (permeability of rhodamine 123, a P-glycoprotein substrate, across rat jejunum membranes after Glycyrrhiza inflata and Daphne genkwa decoctions, alone and combined). Reference information, not medical advice.

Western / Biomedical Research

Chinese Herb Clinical Studies & Research

Provided as research context — a summary of published biomedical study, not a therapeutic or medical claim.

• Is there modern research on Yuan Hua (Daphne genkwa)?

  Yes, and it splits cleanly in two: research into the daphnane diterpenes as potential anticancer and anti-inflammatory lead compounds, and research into the plant’s toxicity and its classical incompatibility with licorice. The first is isolated-compound pharmacology at the drug-discovery stage; none of it describes a use for the crude herb.

  • Diterpene chemistry. The flowers are a rich source of daphnane diterpenoids; 37 have been structurally characterised from the flowers in a single recent study, nine of them previously undescribed. A dedicated review covers ten named analogues of the yuanhua series and the signalling pathways implicated in their antitumour effects, with protein kinase C identified as a key factor for the lead compound.
  • Anticancer investigation. Yuanhuacin has shown activity in laboratory and animal models of lung and breast cancer; new daphnane-type diterpenes isolated from the flower buds have been screened for cytotoxicity against breast and liver cancer cell lines. This is preclinical compound work, a long way from any clinical use.
  • Antiviral activity. A water extract of the dried buds inhibited enterovirus 71 by blocking viral entry rather than by acting on infected cells, without cytotoxicity at the concentrations tested.
  • Incompatibility research. The genkwa-and-licorice pair has been examined by biochemistry, histopathology and metabonomics in rats, and by high-resolution mass spectrometry with a supramolecular self-assembly model that proposes a chemical mechanism for the enhanced toxicity. This is one of the better-studied of the classical incompatibility pairs.
  • Quality control and authentication. Untargeted metabolomics with high-resolution mass spectrometry has been used to distinguish crude from vinegar-processed material and to identify marker compounds for each — work driven by the need to tell processed material apart reliably in commerce.

  Sources: PMID 42329339, DOI 10.1007/s11418-026-02056-z; PMID 35204693, PMC 8961543, DOI 10.3390/biom12020192; PMID 30406671, DOI 10.1080/14786419.2018.1536133; PMID 22590685, PMC 3347322, DOI 10.3390/v4040539; PMID 30339979, DOI 10.1016/j.jep.2018.10.014; PMID 35004606, PMC 8733466, DOI 10.3389/fchem.2021.740952; PMID 37241730, PMC 10223954, DOI 10.3390/molecules28103990; PMID 38906384, DOI 10.1016/j.fitote.2024.106089. Research context, not a therapeutic claim.

Chinese Herb Notes

• Why must Yuan Hua not be combined with Gan Cao, and how does it compare with Gan Sui and Jing Da Ji?

  Yuan Hua and Gan Cao (licorice) form one of the classical “Eighteen Incompatibilities” (shi ba fan) — the traditional list of herb pairs held never to be combined in one prescription. The Sacred Lotus records this pairing explicitly. It is not an isolated rule: the same classical couplet places licorice against four medicinals together — Gan Sui (kansui), Jing Da Ji (Peking spurge root), Yuan Hua (genkwa) and Hai Zao (sargassum) — and our records hold all four of those pairings.

  • Where the rule comes from. A history of the doctrine traces the “seven relations” framework to the Divine Husbandman’s Classic of the Materia Medica, with the explicit prohibition on combining licorice with kansui, genkwa, Peking spurge and sargassum first stated in the Variorum of the Classic of the Materia Medica and later condensed into the mnemonic verse that students still learn.
  • Modern investigation supports this particular pair. In rats, genkwa alone at three times the pharmacopoeial maximum dose damaged heart, liver, kidney and testis; the genkwa-plus-licorice combination produced comparable liver injury but aggravated the kidney and reproductive toxicity. A separate chemical study offers a mechanism: glycyrrhizic acid from licorice and yuanhuacine from genkwa self-assemble into a supramolecular complex through hydrophobic interaction, and that complex was more cytotoxic to liver cells than genkwa alone.
  • The parallel evidence from kansui. The licorice-and-kansui pair, from the same couplet, has been studied in more depth still — by dose-ratio experiments in a pleural-effusion model and by plasma and tissue metabolomics, which identified heart, liver and kidney as the target organs of the incompatible combination. The historical rule is not uniformly reproduced across every study, but for these particular pairs the modern data broadly point the same way as the classical warning.
  • How it differs from its category-mates. Gan Sui and Jing Da Ji drive water by the same drastic route; the traditional distinction places Yuan Hua more toward fluid congested in the chest and flanks, and gives it the additional external role against parasitic skin disease that the others lack. All three sit in the same risk class, and all three are named against licorice.

  A naming point worth stating. The “Da Ji” of the classical couplet is Euphorbia pekinensis — the herb listed here as Jing Da Ji — and not the similarly romanised Da Ji, Japanese thistle (Cirsium japonicum), which is a blood-cooling haemostatic in an entirely different category. Our records currently carry an incompatibility entry pairing Gan Cao with the thistle as well as with Jing Da Ji. We have flagged that to the site editor as a probable romanisation collision rather than altering it here.

  Formula composition note. Our record for Shi Zao Tang lists the three toxic expellants in equal quantity but does not list the jujube (Da Zao) that gives the formula its name. In the classical transmission the jujubes are the vehicle rather than a co-decocted ingredient, so the omission may be intentional; we have raised it for the editor and changed nothing.

  Sources: Sacred Lotus incompatibility and formula records; PMID 26420521 (history of the licorice/sargassum/Peking-spurge/kansui/genkwa prohibition and its modern reception); PMID 30339979, DOI 10.1016/j.jep.2018.10.014 (genkwa alone versus genkwa with licorice in rats); PMID 35004606, PMC 8733466, DOI 10.3389/fchem.2021.740952 (glycyrrhizic acid and yuanhuacine self-assembly; greater cytotoxicity of the complex); PMID 27084456, DOI 10.1016/j.jep.2016.04.012 and PMID 31929940, DOI 10.1016/j.jpha.2019.05.005 (kansui-licorice dose-ratio and metabolomic studies). Reference information only.

This herb is incompatible with:

• Gan Cao (Radix Glycyrrhizae)

This herb is considered toxic