Part 2 of 6 in the "Chinese herb risks and checkpoints" series. The list of the other five is at the foot of this part.
Part 1 drew the boundary: what has a record is Aristolochia plants, which contain aristolochic acid. This part takes the next question — how the record describes it, and how the recorded cases actually happened.
The short version
- Hong Kong's Chinese Medicine Regulatory Office page sets out the cause of poisoning, the symptoms and the management item by item; it does not describe how the acid acts inside the body, so this part stops in the same place.
- Hong Kong's recorded cases were a mix-up between plants of two families: similar names, similar looks, different botanical sources.
- That is why the same page sets the herbs "without" beside those "with". It is identification material for the person composing a mix, not a self-check list for a reader.
- What NPRA's step controls is the formulation: prohibited ingredients may not be in it, and products containing List A or List B plants must be tested. "Registered" means checked for this class, not that everything about it is safe.
First, the things that cannot wait
⚠️ A safety note: TCM and Western medicine complement each other; it is not a choice between them. If you experience a severe allergic reaction (such as difficulty breathing or facial swelling) or loss of consciousness after taking herbs, call 999 now, or go to the nearest hospital emergency department.
Who needs extra care, what to do first if you feel unwell, and the reason behind each item are in part 6.
A note: this section is general information only. For conditions like these, follow your doctor's diagnosis and treatment, and seek medical attention when you need it.
I. The four stations a medicine passes through, and the lines the record keeps
A medicine that enters the body passes four stations: absorption in the gut, entry into the blood and distribution through the body, metabolism in the liver, excretion by the kidneys — that is how the Hong Kong Hospital Authority's pharmacist and Chinese medicine pharmacist put it in a public lecture.
They use these four stations to show where Chinese and Western medicines affect each other: the first four routes each happen at one station, and the last two are the effects themselves adding up or cancelling out. The six routes, each with the Hospital Authority's own example, are in section II of "Can You Take Chinese Herbs With Western Medication?" (/chinese-herbs-with-western-medicine/); here we borrow only the four-station frame rather than repeat that article.
The reason for borrowing it is simple: when a class of herb causes a problem, the place it does so is one of those four stations.
① How the record describes it. Hong Kong's Chinese Medicine Regulatory Office page sets it out item by item. Cause of poisoning: aristolochic acid is highly toxic, can cause kidney failure and urinary-tract cancer, and the page states it has been classified by the World Health Organization as a 「甲級致癌物」 (甲级 carcinogen). Symptoms of poisoning: kidney failure and urinary-tract cancer, and in severe cases even death. Management: seek medical attention immediately.
That page records the consequences and what to do; it does not describe how the acid acts inside the body — nothing on the mechanism, nothing on whether it accumulates, nothing on dose. So this article stops there too.
A note: this section is general information only. For conditions like these, follow your doctor's diagnosis and treatment, and seek medical attention when you need it.
II. Where things went wrong: one name, plants from two families
② Hong Kong's recorded cases were 寻骨风 (Aristolochia family) used in place of 白英 (nightshade family), and 广防己 (Aristolochia family) in place of 防己 (of the 防己 family), leading to adverse reactions to Chinese medicine — the same page's account.
The page then sets the herbs "without aristolochic acid" beside those "with" it: 白毛藤 against 寻骨风, 川木通 against 关木通, 防己 and 川木香 against 广防己 and 青木香, each with its botanical source and appearance. Similar names, similar looks, different plants: that is why the checkpoint sits at identification and sourcing.
One thing needs saying plainly: that paired material is for the person composing the mix, not a checklist for you to run at home. What it gives is botanical source and morphology, usable only with the material in hand and training behind it. What you can do is not identify a herb but ask where the packet came from and who composed it — parts 3 and 4 cover both.
💡 Remember: the risk in this class is not in the words "Chinese herbs"; it is in a herb being mistaken for another one. So the checkpoint sits at sourcing and identification, not at drinking a little less.
III. Why "registered" is the checkpoint for this class
③ NPRA's guideline states that prohibited ingredients are not allowed in the formulation of natural products registered by the Authority, and that the whole Aristolochia genus is totally banned. For botanicals known or suspected to contain aristolochic acid (List A), and botanicals that may be adulterated with it (List B), products containing them must be sent to a governmental doping centre for testing, with the result attached to the registration form — all in the same guideline.
List B includes 木通 (Akebia), 川木通 (Clematis armandii), 川木香 (Vladimiria souliei), and Stephania species other than 粉防己. 川木通 and 川木香 are the very two herbs set beside 关木通 and 青木香 on the Hong Kong page. And 粉防己 itself (Stephania tetrandra, the "防己 of the 防己 family" on that Hong Kong page) is separately listed in NPRA's banned table, with the reason "Reported to cause kidney toxicity".
Put together: a product with a MAL number is one whose formulation was checked against the banned list, and, if it contains a List A or List B plant, was tested before registration. Hong Kong applies the same logic to proprietary medicines containing Asarum herbs: "no aristolochic acid detectable" is written into the quality standard. "Registered" means "checked for this class". It does not mean "everything about it is safe".
④ Where this checkpoint does not reach. Loose herbs and a practitioner's own dispensing are exempt from registration, so they do not pass through that formulation review — the wording of the exemption, what holds that kind instead, and how to check a packaged product are all in part 3.
These are the regulators' own listed examples, not a list where anything unlisted is safe.
A note: this section is general information only. For conditions like these, follow your doctor's diagnosis and treatment, and seek medical attention when you need it.
The words in this part
All four are words the material itself uses: the first from the Hospital Authority's lecture, the other three written into NPRA's registration guideline.
- Absorption, distribution, metabolism, excretion (吸收、分布、代谢、排泄) — the Hospital Authority's four stations for a medicine's journey through the body: absorption in the gut, entry into the blood and distribution through the body, metabolism in the liver, excretion by the kidneys.
- List A and List B — two lists in NPRA's guideline. List A is "Botanicals Known or Suspected to contain Aristolochic Acid"; List B is "Botanicals that may be Adulterated with Aristolochic Acid". Both do the same job: a product containing a listed plant must be tested before registration.
- Adulterated (掺入) — something mixed into a formulation that should not be in it. List B's title uses this word, so what it targets is not what a plant contains in itself.
- Totally banned (整属禁用) — the guideline's footnote states that products containing other listed herbs may be tested and the result attached, except for Aristolochia species, which are totally banned: not some species, all of them.
Frequently asked
If it has a MAL number, does that mean this bottle is safe? No. The number means this product went through the registration review — under NPRA's guideline its formulation has to be checked against the banned list, and if it contains a List A or List B plant it has to be tested too. What the review controls is whether the formulation contains anything it should not, not whether this bottle suits you — that second question belongs to the consultation. How to check a number is in part 3. If you have an existing kidney condition, follow your doctor's diagnosis and treatment.
Loose herbs weighed out at a medical hall have no number — then what? NPRA's guideline states that loose herbs and a practitioner's own on-the-spot dispensing are exempt from registration, so they never had a MAL number; that is how the system works. The checkpoint sits at sourcing and identification: ask what is in the packet, what situation it was composed for, and whether the person composing it knows those herbs. Storage is part 5.
Do not: work through the paired names above against the packets in your kitchen. That material is used for botanical identification, not text matching; names that match while the material does not is the whole starting point of this story.
A note: this section is general information only. For conditions like these, follow your doctor's diagnosis and treatment, and seek medical attention when you need it.
The other five parts
- Part 1: Do Chinese herbs carry risks? Which class has the record, and how Malaysia regulates it
- Part 3: Can I take what I bought? Reading and checking the MAL number and Meditag
- Part 4: One table: what you are holding, and how to check it
- Part 5: Storing Chinese herbs — herbs and 凉茶 ingredients in a hot, humid climate, and when "too long" starts
- Part 6: Situations that need extra care — who asks a doctor and a practitioner first, and what to do if you feel unwell
👉 If you are unsure whether "this packet of herbs, or this bottle of proprietary medicine in my hand, is actually right for me to use", you are welcome to book an online consultation with HansMed, where a practitioner registered under the T&CM Act 2016 assesses it with you.
Sit with a licensed TCM practitioner from wherever you are.
HansMed Modern TCM
For general wellness education only — not medical advice. Consult a registered TCM practitioner for personal guidance.
Sources
- Chinese Medicine Regulatory Office, Department of Health, Hong Kong, reference material on Chinese herbs associated with adverse events in Hong Kong: herbs containing aristolochic acid — https://www.cmro.gov.hk/html/b5/useful_information/public_health/publication/AdverseEvents13.html
- National Pharmaceutical Regulatory Agency (NPRA), Ministry of Health Malaysia, Drug Registration Guidance Document, Third Edition, 12th Revision July 2026, Appendix 7: Guideline on Registration of Natural Products — https://www.npra.gov.my/easyarticles/images/users/1153/drgd_appendices/APPENDIX-7-Guideline-on-Registration-of-Natural-Products.pdf
- Hong Kong Hospital Authority Smart Patient, lecture slides "當中藥師遇見藥劑師——認識中西藥相互作用", Mr. Chui Chun Ming (Chief Pharmacist) and Ms. Lam Kit Yu (Manager, Chinese Medicine) — https://www.smartpatient.ha.org.hk/smart-patient-web/useful-information/sp-series/sp-series-details/%E8%97%A5-%E5%AF%86-%E8%A7%A3%E9%8E%96%E8%AC%9B%E5%BA%A7
