Camphor in Traditional Chinese Medicine (Zhang Nao): What the Texts Say and What They Do Not

Zhang nao (樟脑) is the Chinese name for camphor crystals obtained from the camphor tree, Cinnamomum camphora. In traditional Chinese medicine (TCM) it is classed as a pungent, hot, slightly toxic material used mainly on the skin, with a very small internal dose recorded only under practitioner control. This is a record of tradition, not advice.

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Start with the name, because two camphors share it

Most confusion about camphor in Chinese sources comes from one translation problem. Chinese writers distinguished longnao xiang (龍腦香), the crystalline resin of the Southeast Asian tree Dryobalanops aromatica, from zhang (樟), the Cinnamomum camphora tree of southern and eastern China. A historian of medieval Chinese religion summarizes the second material as "sublimated and distilled common camphor" and notes that the shift from the imported resin toward the domestic tree is poorly documented, with the mid-to-late eleventh century showing "some indications of this change" (Romaskiewicz).

That matters for modern readers because the Chinese Pharmacopoeia lists bingpian (冰片, borneol), not camphor, as the standard aromatic "orifice-opening" crystal. Its monograph for borneol describes it as slightly cold, pungent and bitter, and caps camphor as an impurity at 0.50 percent (Shennong Alpha database, citing the 2015 and 2020 editions). Zhang nao is a different material with a different thermal character, which is why a TCM paragraph about "camphor" can describe two substances in opposite terms. For the Indian side of the same confusion, see our piece on edible camphor versus regular camphor.

The tree itself, its chemistry and its range are covered in the tree behind camphor oil. The first Chinese references are older than the zhang camphor trade: a historian lists early sixth-century translated Buddhist sutras and the mid-seventh-century Book of Liang for the substance in general, and the Newly Revised Materia Medica (mid-seventh century) as the firmer early materia medica citation, with a possible late-fifth-century source flagged by that author with a question mark (Romaskiewicz). For the wider trade story, read the history of camphor and a thousand years of camphor.

How TCM sources describe zhang nao

Modern English references agree on the core classification, though they differ in detail. Two practitioner-facing summaries describe zhang nao as pungent, hot and slightly toxic, entering the Heart and Spleen channels (Acupuncture Today; Me & Qi herb database). The second places it in two categories: aromatic substances that open the orifices, and substances for external application.

Concept	What the sources say	Plain meaning
Flavor and temperature	Pungent (xin), hot	A warming, dispersing material in TCM theory
Channels	Heart, Spleen	Where the material is said to act
Toxicity label	"Slightly toxic" (xiao du)	The tradition itself flagged risk
Category	Opens the orifices; external-use substance	Used for fainting-type presentations and mostly applied on the skin
Recorded external uses	Scabies, ringworm, toothache, frostbite, sprains, burns, insect bites	Powder, alcohol solution, oil liniment or lard-based ointment
Recorded internal use	0.06 to 0.15 g per dose in pills or powders, not above 0.2 g (Me & Qi)	Tiny, practitioner-controlled, never in a decoction

Those external indications are reported as what practitioners historically did, not as results. Neither summary gives a historical text citation for them: the Acupuncture Today page cites modern references (the German Commission E, Chen and Chen's 2004 Chinese Medical Herbology and Pharmacology, and the AHPA Botanical Safety Handbook), and the Me & Qi page cites none. We therefore treat the table as a modern summary of tradition, not a quotation from a classical text.

Where the summaries disagree

Two points deserve a plain flag instead of an average. First, the part used. One summary says leaves are the primary part used in herbal preparations and that the whole tree is used in traditional practice (Acupuncture Today). The other lists zhang nao as a processed product, not a plant part (Me & Qi). The historical account fits the second: sublimated and distilled crystals. Wood, root and leaf oils are different materials from the crystals.

Second, the dose. The only numeric internal dose we found (0.06 to 0.15 g) comes from a single herb database that does not cite a classical or pharmacopoeial source, so we repeat it only as that database's statement. We could not locate a Chinese Pharmacopoeia monograph for camphor itself in the sources we opened. Do not use this article to work out a dose of anything.

Why the tradition kept it out of the pot

The most useful practical detail in the TCM material is a restriction. The Me & Qi summary says zhang nao "must NOT be added to decoctions" because it is volatile and evaporates when boiled, and that internal forms are pills, powders, or alcohol solutions, while external forms are powder, liniment or ointment. This is consistent with the physical behavior of the material, and it is the same reasoning behind amber glass and tight closures for the oil. It also shows that the tradition handled camphor differently from ordinary herbs, as something dosed in fractions of a gram or kept to the skin.

The cautions listed in the same sources read like a modern safety sheet. They name pregnancy, breastfeeding, children (Me & Qi says under 2 should avoid it), epilepsy or seizure disorders, open wounds, and liver or kidney impairment. The American Herbal Products Association rates camphor class 2B and 2D, advising against use in pregnancy and against application to the face of infants and children, and the German Commission E advises against applying it to burned or injured skin (as reported by Acupuncture Today). Our standing position matches these: see whether camphor oil is safe.

What modern toxicology says about the "slightly toxic" label

"Slightly" understates the modern data. A 2006 evidence-based guideline from poison-center and toxicology specialists, Camphor Poisoning: An Evidence-Based Practice Guideline for Out-of-Hospital Management, notes that absorption from the gut is rapid, that irritation, nausea and vomiting can appear within 5 to 15 minutes, and that generalized convulsions are often the first sign of significant toxicity. It recommends emergency department referral for anyone who has ingested more than 30 mg/kg of a camphor product or shows moderate to severe symptoms (Manoguerra et al., Clinical Toxicology 2006;44:357-370). The same guideline reviewed child cases and recorded that poison-center referral thresholds ranged from 15 to 30 mg/kg across centers.

A Chinese pharmacovigilance review reaches a similar view from the other direction. Its authors, at Tianjin University of Traditional Chinese Medicine, describe camphor as widely used but notably toxic, with evident toxicity to the nervous system, liver, heart, fetus and pregnant women (Ding, Ma and Zhang, Chinese Journal of Pharmacovigilance, 2012). The same Me & Qi summary states oral toxicity at about 2 g in adults, which is far above its own recorded dose. That gap between a dose in hundredths of a gram and a toxic dose in grams is real, but it narrows sharply for children and for people who mistake a household camphor product for something edible. If anyone swallows camphor, call Poison Help at 1-800-222-1222 (free, confidential, 24 hours, per MedlinePlus) or 911 for an emergency.

The regulatory contrast

US law handles camphor very differently from the TCM tradition. FDA's rulemaking history lists a 1980 proposal and a September 21, 1982 final rule (47 FR 41716) on camphorated oil drug products, later consolidated into 21 CFR 310.502 in 1997 (FDA). Secondary sources summarize the rule as a ban on camphorated oil and an 11 percent cap on camphor in products. We did not open the rule text itself, so confirm the exact scope there before relying on it.

What this does not show

Everything in the TCM columns above is a record of what was done in a tradition, not evidence that camphor works for any listed condition. A 2022 review of Cinnamomum camphora compiled its traditional uses, chemistry and reported pharmacology and called for further research, and it draws mainly on Unani texts rather than Chinese practice (Usmani, Jahan and Sofiya, IJPPS 2022). Our own Camphor Essential Oil is sold as an aromatic and cosmetic material, not a drug, and it is not zhang nao: one is a distilled, fractionated oil, the other a crystalline solid with traditional dosing rules. If you want a TCM opinion on any use, a licensed practitioner who also knows your medications, pregnancy status and any seizure history is the person to ask, together with a pharmacist.

Frequently asked questions

Is zhang nao the same as borneol (bingpian)?

No. Borneol is a separate crystalline compound that the Chinese Pharmacopoeia lists under its own monograph with a different thermal character, slightly cold against camphor's hot. Camphor is only a controlled impurity there.

Does TCM use camphor oil?

The summaries we opened describe crystals as powder, alcohol solution, oil liniment or lard-based ointment. They do not describe the essential oil as sold in aromatherapy, so treat "TCM uses camphor oil" as unsupported by these sources.

Can I follow a TCM dose at home?

No. The only dose we found is a single database's statement, with no classical citation, and the margin to the toxic range is small for children. Ask a licensed practitioner and a pharmacist.

Where does camphor fit in other traditions?

The ritual and trade dimensions are covered in camphor in ritual and tradition, and the Indian medical tradition in our piece on camphor in Ayurveda.

If you came here to buy an aromatic oil

Keep the two ideas apart. Our Camphor Essential Oil is a white-fraction aromatic oil, and how it is made and what we ask of each lot is on Inside the Still. The traditional material above is a different thing with a different risk profile.