Heavy Metals in Traditional Medicines: Lead, Mercury, Arsenic and Cadmium
What studies and regulators have found about lead, mercury, arsenic and cadmium in some traditional medicines, what the findings do not show, and how to lower your risk.
Content last updated . This page has not been medically reviewed.
Urgent first
If someone is severely unwell, or a child may have swallowed a product, call 911 in the United States. Poison Help is 1-800-222-1222. See poisoning: what to do first.Why metals appear in some products
There are two different routes. Metals can be present as an intentional ingredient: in Ayurveda, the practice of rasa shastra combines herbs with metals and minerals, and a review of Bhasmas (Ayurvedic) and Zuotai (Tibetan) notes that the metals found in Ayurveda are mainly from intentional addition. [1][2] Metals can also be present by accident, from soil, water or manufacturing. Reviews of herbal products worldwide find that contamination varies between settings and products. [3] Traditional systems that use processed metals describe their own purification steps; that is a traditional framework, and the studies below test finished products, not the framework.What studies found
These are studies of the products tested, not of every product in a tradition.| Study | What it found |
|---|---|
| Ayurvedic products from South Asian stores in the Boston area (2004) | 14 of 70 contained lead, mercury and/or arsenic, and each could exceed regulatory standards if taken as recommended. [4] |
| Ayurvedic medicines bought on the internet (2008) | One-fifth contained detectable metals, with similar rates for US-made and Indian-made products, and more in rasa shastra products (40.6% vs 17.1%). [1] |
| 2,245 batches of Chinese herbal medicines (2020) | Most were not an unacceptable risk for the average user, but the high-exposure group needed more attention. [5] |
| Systematic review of herbal medicines (2026) | 70 studies from 27 countries or territories; contamination varied by setting and product. [3] |
NCCIH states that some Ayurvedic preparations may contain lead, mercury or arsenic in amounts that can be toxic, and cites a 2015 survey in which 40 percent of people who use Ayurvedic preparations had elevated blood lead. [6] These samples came from specific markets and years, so they cannot tell you the risk of a particular product today. Health Canada has issued warnings about specific Ayurvedic and other unauthorized products, one noting a poisoning case and another lots with high lead and mercury. [7][8]
Other traditions
A 2026 case report links heavy metal toxicity to a Siddha product, though the authors say Siddha has only very rarely been reported with lead and mercury poisoning. [9] A review of Zuotai and Bhasmas says metal poisoning case reports from inappropriate use of traditional medicines are increasing. [2] Samples of Mexican folk remedies used for empacho (azarcon, greta and albayalde) were very high in lead. [10] See also Tibetan precious pills, Siddha preparations and Unani products.What you can do
- Ask your clinician before using a mineral, metal-containing or imported traditional product, and especially for a child or in pregnancy.
- Prefer products from sellers who can show independent testing for metals, and note that a "good manufacturing practice" claim does not guarantee testing; in the 2008 study 75% of metal-containing products claimed it. [1]
- If you have used a product and have symptoms, tell a clinician; lead exposure is assessed by measuring lead in blood, so ask your clinician about a test. [11]
- Report problems: reporting a problem with a traditional product.
We cannot tell you which brands are safe, and a clean result in one batch does not cover the next.
Related pages
Ayurvedic products: heavy metals and quality, product quality and contamination, and the safety overview.Frequently asked questions
Do all traditional medicines contain heavy metals?
No. In the studies, a minority of products tested had detectable metals, about one-fifth in two Ayurvedic studies. [4][1]
Are metals in rasa shastra products deliberate?
Yes, in that tradition metals are added on purpose; the 2008 study found a higher rate of metals in these products. [1][2]
Are Chinese herbal medicines safe from metals?
In a large batch study most herbs did not pose an unacceptable risk for the average user, but some herbs and high-exposure users did. [5]
Can children be harmed?
Yes. WHO says lead is particularly harmful to young children. [11]
Can I test a product at home?
Not that we know of from the sources we read. Ask a clinician or pharmacist about testing, and about a blood test if you have symptoms. [11]
More details: evidence, limits and cautions
The details behind this page: cautions, limits of the evidence and where sources disagree. Open any note to read it.
Who is most at risk
References
- Saper RB and others. Lead, mercury, and arsenic in US- and Indian-manufactured Ayurvedic medicines sold via the Internet. JAMA 2008. Read 2026-10-22.
- Chemical compositions of metals in Bhasmas and Tibetan Zuotai are a major determinant of their pharmacologic properties and safety. Evidence-Based Complementary and Alternative Medicine 2019. Read 2026-10-22.
- Boulares E and others. Heavy metal contamination in herbal medicines: a systematic review and meta-analysis. Reviews on Environmental Health 2026. Read 2026-10-22.
- Saper RB and others. Heavy metal content of ayurvedic herbal medicine products. JAMA 2004. Read 2026-10-22.
- Zuo T-T and others. Innovative health risk assessment of heavy metals in Chinese herbal medicines based on extensive data. Pharmacological Research 2020. Read 2026-10-22.
- National Center for Complementary and Integrative Health. Ayurvedic Medicine: In Depth. Read 2026-10-22.
- Health Canada. Health Canada Reminds Consumers that Some Ayurvedic Medicinal Products Contain High Levels of Heavy Metals. Archived 2008 news release, read 2026-10-22. Read 2026-10-22.
- Health Canada. Health Canada Advises Consumers not to use two Unauthorized Natural Health Products due to Heavy Metal Contamination. Archived 2006 news release, read 2026-10-22. Read 2026-10-22.
- Tan Z and others. Cerebral edema secondary to heavy metal toxicity from Siddha medicine: a case report and case-based review. Case Reports in Neurological Medicine 2026. Read 2026-10-22.
- Baer RD and others. Toxic Mexican folk remedies for the treatment of empacho: the case of azarcon, greta, and albayalde. Journal of Ethnopharmacology 1988. Read 2026-10-22.
- World Health Organization. Lead poisoning and health. Fact sheet. Read 2026-10-22.
- World Health Organization. Mercury and health. Fact sheet. Read 2026-10-22.