Rou Gui (Inner Bark of Saigon Cinnamon)

Chinese Herb Actions

Chinese Herb Dosage

• What is the typical dosage of Rou Gui?

  1–4.5 g in decoction, added near the end of cooking (hou xia) to preserve its volatile oil; 1–2 g when powdered and taken directly. It is a warm, potent herb used in relatively small amounts.

  Source: owner’s Five Branches notes (0.5–1.5 qian); standard materia medica ranges. Reference only — not a prescription.

Chinese Herb Contraindications & Cautions

• Are there cautions or contraindications for Rou Gui?

  Rou Gui is hot and drying, so it is contraindicated in yin deficiency with heat signs, in interior excess heat, and in reckless movement of hot blood (bleeding due to heat). It is also cautioned against, or avoided, during pregnancy. Per the classical Nineteen Antagonisms, it is traditionally not combined with Chi Shi Zhi (Halloysite).

  Source: owner’s Five Branches notes (contraindications); classical incompatibility lists.

Chinese Herb Toxicity & Overdose

• Low at traditional therapeutic doses. Cassia cinnamon bark naturally contains coumarin (roughly 3 mg per gram of bark), and the European Food Safety Authority sets a tolerable daily intake for coumarin of 0.1 mg/kg body weight, so concentrated or high, long-term intake is a theoretical hepatic concern in sensitive individuals. In practice, a clinical study of traditional (Kampo) formulas containing cinnamon bark found no measurable liver injury attributable to the herb even where many patients exceeded the coumarin intake limit.

  Sources: PubMed 27378929 / PMC 4913087 (coumarin intake from cinnamon-bark traditional medicines vs. hepatotoxicity); EFSA coumarin tolerable daily intake. Research context, not a therapeutic claim.

Herb-Drug Interactions

• No well-established clinical herb–drug interactions are documented. Because cinnamaldehyde lowers glucose in animal studies (below), a theoretical additive effect with antidiabetic drugs is reasonable to monitor. Note that the coumarin in cassia is simple coumarin (1,2-benzopyrone), not the 4-hydroxycoumarin anticoagulant class (warfarin/dicoumarol), so cinnamon bark is not itself a blood thinner. (Flagged for practitioner confirmation — absence of documented interactions is not proof of safety.)

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 cinnamon bark (Rou Gui / Cinnamomum cassia)?

  Yes, but it is largely preclinical. The most-studied constituent is cinnamaldehyde, the main compound of the bark’s volatile oil. In macrophage and animal models it shows anti-inflammatory activity — concentration-dependently lowering nitric oxide, TNF-α and PGE2 and downregulating iNOS, COX-2 and NF-κB. In diabetic animals cinnamaldehyde and cassia oil improved glucose uptake and insulin sensitivity (via PPAR/AMPK signaling). Human clinical evidence remains limited.

  Sources: PubMed 22536283 / PMC 3318905 (anti-inflammatory constituents of Cinnamomum cassia, in vitro & in vivo); PubMed 38903995 / PMC 11187351 (review of cinnamaldehyde pharmacology); PMC 11435133 (cassia oil in alloxan-diabetic rats). Research context, not a therapeutic claim.

Chinese Herb Notes

• How is Rou Gui different from Gui Zhi and Fu Zi?

  Rou Gui is the warming, interior-directed bark that tonifies Kidney yang and leads fire to its source; Gui Zhi is the young twig that releases the exterior and unblocks the channels. Both come from the same cinnamon plant (Cinnamomum cassia), but Rou Gui (the thick inner bark) is hotter and works on the interior and Lower Burner, while Gui Zhi (the twig) is directed outward and upward to warm and free the yang of the exterior and the limbs.

  It also differs from its closest warming neighbor:

  • vs Fu Zi — both warm the Ming Men fire and treat yang deficiency with cold from the Lower Burner. Rou Gui is milder, more focused on the Lower Burner, leads fire back to its source, and additionally warms the channels and moves blood. Unlike Fu Zi, it is not used to rescue collapsed (devastated) yang.

  Common combinations: with Fu Zi (and Shu Di Huang / Shan Zhu Yu, the Shen Qi Wan / You Gui framework) to warm Kidney yang and lead fire back to its source; with Dang Gui and blood-moving herbs to warm and free the channels for cold amenorrhea and dysmenorrhea; added in small amounts to qi-and-blood tonic formulas to warm and promote the generation of qi and blood.

  Source: owner’s Five Branches notes (Fu Zi/Rou Gui comparison & combinations); standard materia medica for the Rou Gui vs Gui Zhi distinction.

This herb antagonizes or is antagonized by:

• Chi Shi Zhi (Hallyositum Rubrum)