Chinese Herbal Products: Quality, Contamination and Medicine Interactions

Urgent first

If someone has taken a Chinese herbal product and has collapsed, had a seizure, 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 being traditional does not make a product safe. Safety depends on which herb it is, what else is in the bottle, and what 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.

Chinese herbal product quality

What has been found in products. 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]

Hidden drugs. 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. The authors advised the public to avoid Chinese proprietary medicines of dubious source. [3] This tells us such products exist and can harm. It does not tell us how common they are in any one country.

Aristolochic acid. In the early 1990s in Belgium, young women taking slimming pills developed rapidly progressive kidney scarring. Investigators found that roots of one herb (Han Fang Ji, Stephania tetrandra) had been mistakenly replaced with roots of an aristolochic acid-containing herb (Guang Fang Ji, Aristolochia fangchi), because the names are similar and both belong to the "Fang Ji" family in TCM. [4] Aristolochic acid exposure is also associated with a high incidence of urothelial (urinary tract lining) cancer, and there is no effective treatment for delaying or reversing the kidney damage. [4] Many countries have banned or restricted products containing it, and the US FDA issued an alert in 2001. [4] The review says occasional cases still occur. [4]

What you can do.

• Avoid products of unknown origin or with no ingredient list, especially those sold as "natural" remedies for diabetes or slimming, the two settings in the cases described above.
• Use a practitioner who can name each herb, its source and its supplier, and ask whether the formula contains any herb from the Fang Ji or Aristolochia group.
• 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 the original packaging and stop the product and contact a clinician or pharmacist if you feel unwell after starting it.

The general quality issues of all supplements are covered on Product Quality and Contamination.

Herb-medication interactions

Warfarin. A review of 44 commonly used Chinese herbal products in Singapore found 11 herbs with the strongest evidence of potential interaction with warfarin: danshen, ginkgo, dong quai, American ginseng, safflower, peach kernel, licorice, Asian ginseng, lycium, ginger and notoginseng. [6] A separate review states that danshen is well known to lead to anticoagulation failure of warfarin. [7] Treat this as a list of reasons to ask, not a complete or ranked list.

Other medicines. The NHS lists medicines that may not mix well with herbal medicines: statins, antidepressants, diabetes medicines, blood pressure medicines, warfarin and hormonal contraception. [5] It advises checking first with a pharmacist before taking a herbal medicine if you take other medicine, including over-the-counter products. [5]

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 because not enough is known about their safety. [5] Tell your surgical team about all herbs before an operation; see Supplements Before Surgery.

Do not stop or change prescribed medicine yourself. Tell your doctor and pharmacist everything you use. [1]

Evidence label for these warnings: evidence of harm for contaminated and adulterated products and aristolochic acid; insufficient evidence to rank how common each interaction is in practice.

Related pages

See Herb Safety and Interactions and How Interactions Work for the general picture, and TCM Qualifications, Licensing and Medical Care for how to check a practitioner.