Chinese Herbal Products: Quality, Contamination and Medicine Interactions

Urgent first

If someone has taken a Chinese herbal product and has collapsed, had a seizure, has trouble breathing, severe vomiting or cannot be woken, call emergency services. In the US, call 911, or Poison Help at 1-800-222-1222 for advice. Other countries are listed on Poison Help by Country. Bring the product and its packaging.

Why Chinese herbal products need extra care

Chinese herbal medicine has a long history of traditional use, but "traditional" does not mean tested or risk-free. Safety depends on which herb it is, what else is in the product, who makes it, and which medicines you take. NCCIH summarizes that some Chinese herbal products have been contaminated with toxic compounds, heavy metals, pesticides and microorganisms and may have serious side effects, and that manufacturing errors in which one herb is mistakenly replaced with another have caused serious complications. [1] What the herbs are traditionally used for is covered on Chinese Herbal Medicine. This page is the safety overview; each concern below has its own page.

The main concerns at a glance

Product quality

NCCIH reports that some Chinese herbal products were contaminated with undeclared plant or animal material; drugs such as warfarin and diclofenac; heavy metals such as arsenic, lead and cadmium; pesticides or sulfites; or incorrect herbs, some of which caused organ damage. [1] An overview of 26 systematic reviews found herbal medicinal products in general were adulterated or contaminated with things such as microbes, toxins, pesticides, toxic heavy metals and prescription drugs, and that for Chinese remedies contamination was the most commonly noted problem. The authors called for stricter quality control and enforcement. [2]

In a Hong Kong case series, 27 people used 29 herbal antidiabetic products that contained undeclared pharmaceuticals, including glibenclamide and phenformin. Seventeen (63%) had clinical toxicity, most commonly low blood sugar. [3] This shows such products exist and can harm. It does not tell us how common they are in any one country. Many products are fine; the point is that you cannot tell from the label alone.

Interactions in brief

A review of 44 commonly used Chinese herbal products in Singapore found 11 herbs with the strongest evidence of potential interaction with warfarin, including danshen, ginkgo, dong quai, licorice and ginger. [4] The NHS lists medicines that may not mix well with herbal medicines: statins, antidepressants, diabetes medicines, blood pressure medicines, warfarin and hormonal contraception, and advises checking with a pharmacist first. [5] See Chinese Herbs and Prescription Medicines for how the evidence looks.

What you can do

• Avoid products of unknown origin or with no ingredient list, especially those sold for diabetes or slimming, the settings in the cases above. [3]
• Ask a practitioner to name each herb, its source and its supplier. See Buying Chinese Herbs Safely.
• In the UK, the NHS advises checking that a herbal medicine has a traditional herbal registration (THR) mark. [5] We could not verify equivalent marks for other countries.
• Keep products in their original packaging. If you feel unwell after starting one, stop it and contact a clinician or pharmacist; see Warning Signs After Taking Herbs.
• Tell your doctor and pharmacist everything you use, and do not stop or change prescribed medicine yourself. [1]

Who is at higher risk

The NHS says not to take herbal medicines if you are pregnant or breastfeeding or have kidney or liver problems, and that they are not recommended for children. [5] Tell your surgical team about all herbs before an operation; see Supplements Before Surgery.

Related pages

Herb Safety and Interactions, How Interactions Work, and TCM Qualifications, Licensing and Medical Care for checking a practitioner.