Hai Tong Pi (Coral Bean Back)

Chinese Herb Actions

Chinese Herb Dosage

• What is the typical dosage of Hai Tong Pi?

  Our record gives two published ranges: 6–12 g in decoction from one source and 6–15 g in decoction from another. They agree on the floor and differ only on the ceiling, which is ordinary editorial variation between materia medica texts rather than a real disagreement about the herb.

  • Decoction — 6–12 g (Chen); 6–15 g (Bensky), per our record.
  • Part used — the bark.
  • External use — commonly prepared as a soak, wash or steaming preparation for painful joints and for itching skin, in which case it is applied rather than swallowed. Recorded as documented practice; no preparation instructions are given here.

  One reason to keep this herb with a practitioner: the botanical source of material sold as Hai Tong Pi is not uniform (see notes), and dose figures assume you have the article the text was written about. That is an unusually live concern for this particular herb.

  Source: our own herb record dosage entries and part used, cross-referenced against multiple online sources and published materia medica consensus. Reference only — not a prescription and not dosing advice.

Chinese Herb Contraindications & Cautions

• Are there cautions for Hai Tong Pi?

  Our own record notes no specific traditional contraindications for Hai Tong Pi, and no established human safety problem is documented for the decocted bark at conventional doses. That is the honest starting position. Two reference points belong alongside it, neither of which is a warning about ordinary traditional use.

  • Our record — no cautions noted, and no toxicity noted.
  • The evidence base is thin, not clean — a 2023 evidence-based review of the Erythrina genus states plainly that toxicity and clinical studies of these plants are only limitedly reported. Absence of documented harm here reflects absence of study, and should not be read as a demonstration of safety.
  • Botanical identity — because material sold under this name is not always the same plant (see notes), the safety profile of a given batch is only as certain as its identification.
  • Alkaloid class — Erythrina species carry erythrinane alkaloids with documented activity at nicotinic acetylcholine receptors. This is laboratory pharmacology of isolated compounds and extracts rather than a reported effect of the decocted bark, but it is a reason to treat this herb as a practitioner’s medicine rather than a casual one. See the toxicity section.
  • Pregnancy — no specific contraindication is recorded in our own materia medica for this herb, and we do not assert one. As with any wind-damp herb whose safety data are limited, it is a matter for a qualified practitioner.

  Source: our own herb record caution and toxicity entries; limited-evidence statement per PMID 38044940, PMC 10690608, DOI 10.3389/fphar.2023.1281150; alkaloid pharmacology per PMID 22228954, PMC 3249914 and PMID 7498257. Reference information, not medical advice.

Chinese Herb Toxicity & Overdose

• Are Erythrina alkaloids dangerous? Is Hai Tong Pi toxic?

  Our record notes no toxicity for the bark, and the decocted bark at conventional doses has no documented acute toxicity in the sources we checked. The pharmacology of the isolated Erythrina alkaloids is nonetheless real and worth stating accurately: this genus produces compounds with curare-like, neuromuscular-blocking activity. Both halves of that sentence matter, and separating them is the point of this section.

  • What the alkaloids do — Erythrina species yield tetracyclic erythrinane alkaloids that act at nicotinic acetylcholine receptors. Dihydro-β-erythroidine, derived from this genus, is a standard laboratory nicotinic-receptor antagonist used routinely in neuroscience; erysodine, a related Erythrina alkaloid, is characterised in the pharmacology literature as a competitive, reversible antagonist at neuronal nicotinic receptors. Blocking these receptors at the neuromuscular junction is the mechanism curare works by, which is why the historical description “curare-like” attaches to this genus.
  • What has been reported for the bark specifically — a review of Erythrina variegata lists neuromuscular blocking among the pharmacological effects reported for the plant, alongside smooth-muscle relaxant, central-nervous-system depressant and hydrocholeretic activity, noting these are consistent with its indigenous medicinal uses.
  • Proportion — what this does not mean — there is no reported record of clinical neuromuscular blockade from taking Hai Tong Pi as a decoction. The alkaloid content of a bark decoction and the intravenous dose of a purified alkaloid in a laboratory are not comparable exposures. This is presented as accurate pharmacology of the plant group, not as an alarm about the herb.
  • What is genuinely unknown — the 2023 evidence-based review of the genus states that toxicity and clinical studies are only limitedly reported. There is no adequate human safety dataset for this herb in either direction.
  • No dose ceilings, preparation methods or monitoring guidance are given here. These are documented reference facts.

  Sources: our own herb record toxicity entry; PMID 22228954, PMC 3249914, DOI 10.4103/0973-7847.70908 (Erythrina variegata review: neuromuscular blocking, smooth-muscle relaxant, CNS-depressant and hydrocholeretic effects); PMID 7498257, DOI 10.1016/0014-2999(95)00191-m (erysodine as a competitive antagonist at neuronal nicotinic acetylcholine receptors, and its relation to dihydro-β-erythroidine); PMID 31226894 and PMID 30767297 (reviews of Erythrina alkaloids and their pharmacology); PMID 20334036 (Erythrina and related alkaloids, chemistry review); PMID 38044940, PMC 10690608 (limited toxicity and clinical data across the genus). Neutral reference facts, not a safety guarantee and not usage guidance.

Herb-Drug Interactions

• Does Hai Tong Pi interact with medications?

  No herb–drug interactions are documented. A 2023 evidence-based review of the Erythrina genus states explicitly that no interactions were recorded in the literature it surveyed — but the same review notes that clinical and toxicity data for these plants are limited, so this is an absence of findings rather than a positive finding of safety.

  • The one theoretical concern worth naming — because Erythrina alkaloids act at nicotinic acetylcholine receptors and neuromuscular blocking has been reported for extracts of this species, a practitioner would reasonably want to know about herbal use before surgery involving neuromuscular blocking agents. This is precautionary reasoning from mechanism, not a demonstrated interaction, and no case has been reported.
  • Botanical identity again — any interaction reasoning assumes you know which plant the material is. For this herb that assumption is weaker than usual.

  Anyone taking prescription medication, or scheduled for surgery, should raise any herbal product with their doctor or pharmacist. (Flagged for practitioner confirmation.)

  Sources: PMID 38044940, PMC 10690608, DOI 10.3389/fphar.2023.1281150 (no recorded interactions; limited clinical and toxicity data); PMID 22228954, PMC 3249914 (neuromuscular blocking reported for Erythrina variegata). 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 Hai Tong Pi (Erythrina variegata)?

  Yes, but it divides into two literatures that barely speak to each other: a large chemical literature on Erythrina alkaloids, and a smaller Chinese clinical literature on Hai Tong Pi in external preparations for joint pain. Neither yet amounts to clinical validation of the traditional wind-damp indication.

  • Alkaloid chemistry — the genus is one of the better-studied alkaloid sources in the plant kingdom. Tetracyclic erythrinane alkaloids are the major class, with dimeric and more complex structures also reported from E. variegata bark specifically. Reviews describe established anxiolytic and anticonvulsant potential for Erythrina species acting on the central nervous system, and note the striking biosynthetic parallel between erythrinane alkaloids, the morphinans and the Amaryllidaceae alkaloids.
  • Isoflavonoids from the bark — a prenylated-isoflavonoid-rich extract of Erythrinae Cortex has been studied for bone-protective effects in ovariectomised mice, reported as acting through changes in gut microbial composition and metabolites. Animal work, and a different direction from the traditional indication.
  • Other preclinical reports for the bark — antidepressant-like activity with monoamine oxidase regulation in mice, anti-inflammatory and analgesic activity of leaf alkaloids, and antibacterial activity of isolated isoflavonoids. All cell and animal work.
  • Chinese clinical work — Hai Tong Pi appears repeatedly as an ingredient in fumigation-and-washing and ointment preparations for knee osteoarthritis, and data-mining studies of these compounded external formulas identify it as a recurring component. These are studies of multi-herb preparations, not of the single herb, and the trial quality in this area is generally low.
  • The honest gap — the 2023 evidence-based review of the genus concludes that Erythrina plants are promising for further exploration while noting that toxicity and clinical studies remain limitedly reported. That is a fair summary of where this herb stands.

  Reader caution: because the botanical source of commercial Hai Tong Pi is contested (see notes), research conducted on Erythrina variegata does not necessarily describe every article sold under this name.

  Sources: PMID 30767297, DOI 10.1002/ptr.6321 (genus Erythrina: alkaloids, preclinical and clinical studies); PMID 31226894 (updated review of Erythrina alkaloids); PMID 20334036 (Erythrina and related alkaloids, chemistry); PMID 35292327 (dimeric Erythrina alkaloids from E. variegata); PMID 22228954, PMC 3249914 (E. variegata morphology, phytochemistry and pharmacology); PMID 34578822, PMC 8471919, DOI 10.3390/nu13092943 (prenylated isoflavonoid-rich Erythrinae Cortex extract, bone-protective effects in ovariectomised mice); PMID 31600560 (antidepressant activity of E. variegata bark extract in mice); PMID 24660597 (data-mining analysis of fuming-washing formulas for knee osteoarthritis); PMID 38012881 (haitongpi prescription ointment in knee osteoarthritis, transcriptome study); PMID 38044940, PMC 10690608 (evidence-based review of the genus); PMID 33164448 (herbal textual research on Cortex Erythrinae). Research context, not a therapeutic claim.

Chinese Herb Notes

• Which plant does Hai Tong Pi actually come from?

  This is a genuinely unsettled question, and readers should know that before anything else. Our own record gives the pharmaceutical Latin as Cortex Erythrinae — the bark of Erythrina, the coral bean tree — which is the modern pharmacopoeial position: the 1977 Chinese Pharmacopoeia specified the dried bark of Erythrina variegata var. orientalis and E. arborescens. But published herbological textual research reaches a different conclusion about what the classical texts meant, and the commercial market has never been uniform.

  • The modern official source — Erythrina variegata bark (family Fabaceae, the bean family), which is what our record and most contemporary materia medica describe.
  • The textual-research conclusion — a 2020 herbological investigation of Cortex Erythrinae concluded that the authentic article described in the historical materia medica was the dried bark of Bombax malabaricum (the kapok or silk-cotton tree), which is still standardised and used in Guangdong province under the name Guang Hai Tong Pi, and that the Erythrina bark of the 1977 pharmacopoeia corresponds to what the ancient texts called ci tong, a different entry.
  • Why it matters — the same paper records that many varieties have been used in different places under this name, producing what it calls confusion in Cortex Erythrinae commodities. Two unrelated plant families supplying one name is not a trivial substitution: the chemistry is entirely different, and a bark carrying Erythrina alkaloids is not pharmacologically interchangeable with one that does not.

  Discrepancy note: our own record gives the source as Erythrina (Cortex Erythrinae), consistent with modern pharmacopoeial practice, while the published textual research argues the historically authentic Hai Tong Pi was Bombax malabaricum bark — still current in Guangdong as Guang Hai Tong Pi. Additional regional barks also circulate under the name. We report the conflict rather than resolving it, and our identity fields are left unchanged pending review. Anyone relying on this herb should know which botanical source their material actually is.

  What is the coral bean tree?

  Erythrina variegata is a thorny deciduous tree of the bean family, widely planted across tropical and subtropical Asia and the Pacific, known in English as coral tree or Indian coral tree for its brilliant red flowers. The genus contains roughly 115 to 120 species and has been studied heavily for its alkaloids. Different parts of the plant appear in several traditional systems — in Indian medicine the bark and leaves are recorded as a nervine sedative, an eye application, an antiasthmatic and an astringent, uses that sit alongside rather than inside the Chinese wind-damp indication.

  Formula context: our own formula records do not currently link Hai Tong Pi to a classical formula. In modern Chinese practice it appears most often in compounded external preparations for joint pain rather than as a chief herb of the classical repertoire.

  Source: our own herb record pharmaceutical Latin, common name and identity; botanical-source dispute per PMID 33164448, DOI 10.19540/j.cnki.cjcmm.20200627.101 (herbal textual research on Cortex Erythrinae); Erythrina variegata botany and traditional uses per PMID 22228954, PMC 3249914; genus size per PMID 30767297 and PMID 38044940, PMC 10690608. Cross-referenced against multiple online sources and published materia medica consensus.