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Contamination is documented rather than universal. How lead, arsenic and hidden drugs end up in herbal products, and what a serious dispensary does about it.
Where this idea comes from
The fear is built on cases, not on rumours. In the 1990s a slimming clinic in Belgium prescribed a Chinese herb that turned out to be the wrong species, and dozens of women developed kidney failure. Some products sold as natural have been found to contain lead, mercury, arsenic or hidden corticosteroids.
Journalism then generalises, reasonably enough. A confiscated batch becomes a headline about Chinese herbs, and the word Chinese does work that the evidence does not support. Contamination is a supply-chain problem found in many pharmacopoeias, including European ones, and it becomes a Chinese problem in the retelling. Regulators find the same problem in imported slimming and arthritis products from several continents.
What Chinese medicine actually says
The classical pharmacopoeia grades substances by toxicity and specifies processing to reduce it, including soaking, boiling, roasting and pairing with other ingredients. A raw toxic herb and its prepared form are different medicines in the literature, which is why the method matters more than the plant.
Identification is also part of the tradition. Texts describe how to distinguish species by shape, smell and taste, precisely because substitution was a known hazard. The older the text, the more attention it pays to telling one root from another, and that attention is a response to real danger.
What the research says
Some risks are established. Aristolochic acid, present in certain Aristolochia species, is classified by the IARC as a Group 1 carcinogen and is banned in many countries. Adulteration with synthetic steroids or anti-inflammatories has been documented in products marketed for arthritis and weight loss. Documented harm of this kind is rare relative to the volume sold, and it is severe when it happens.
The NCCIH notes both the long history of use and the reports of contamination, misidentification and liver or kidney injury. Regulation 1924/2006 governs what may be claimed for such products in Europe, not what they contain. That gap between claims law and content law is where a buyer needs a supplier they can question.
What you can realistically expect
At the Centre Équilibre in Grenoble, Ghislaine Morin prescribes through the TCM dispensary she runs at the centre, with named suppliers, batch numbers and certificates of analysis for heavy metals and pesticides. Formulas are dispensed for a stated indication and a defined period, not as a general tonic.
Realistically, expect to be asked what else you take and to be told which herb is in the bag and why. Expect a refusal if a product cannot be traced. The honest position is that a plant is a chemical mixture with a source, and the source is the part you can actually check. A dispensary that cannot answer those questions is a shop with a certificate on the wall.
When to consult, and when not to
Consult a practitioner who can name the supplier and show an analysis, especially if you have kidney or liver disease, take anticoagulants, or are pregnant. Ask what happens if a batch is recalled, and expect a written answer rather than a shrug.
Do not buy loose herbs from an unlabelled jar, a market stall or a social media seller, and do not take a product marketed for a disease with a promised outcome. Do not continue anything that coincides with fatigue, dark urine or yellowing skin. Those symptoms need a doctor and a blood test. The question is not whether herbs are natural. It is whether this batch is what the label says.
Frequently asked questions
Are Chinese herbs contaminated?
Sometimes, and the problem is documented rather than imaginary. Heavy metals, pesticides, misidentified species and added pharmaceuticals have all been found in products sold worldwide. A regulated supply chain with batch testing reduces the risk substantially, but no supply chain removes it entirely.
How can I check a herbal product?
Look for a batch number, a named manufacturer and a certificate of analysis covering heavy metals and pesticides. Buy from a dispensary that will answer questions about origin. Avoid products with disease claims, unlabelled powders and anything bought from a social media seller.
Are all Chinese herbs risky?
No. Most are used safely within a supervised prescription, and many have long records of use. The risks cluster around a small number of toxic species, misidentification, contamination and interaction with drugs. That is an argument for traceability and supervision, not for avoiding the tradition altogether.
Useful links
Sources
- IARC Monographs vol. 100A, aristolochic acid, Group 1 carcinogen, 2012 — https://monographs.iarc.who.int/
- NCCIH, "Traditional Chinese Medicine: what you need to know", accessed 2026 — https://www.nccih.nih.gov/health/traditional-chinese-medicine-what-you-need-to-know
- Regulation (EC) No 1924/2006 on nutrition and health claims, 2006 — https://eur-lex.europa.eu/
- Auteur:Ghislaine Morin
- Lien:https://accuponcture-grenoble.com/en/en/article/chinese-herbs-contain-heavy-metals-and-steroids
- Droit d'auteur:Sauf mention contraire, les contenus de ce site sont publiés sous licence CC BY-NC-SA 4.0 — merci d’indiquer la source.