Herbal Tea Adulteration, Mold and Mislabeling
What published reports show about look-alike substitution, mold and mold toxins, natural plant toxins and label mismatches in herbal teas, and what the sources do not tell us.
Content last updated . This page has not been medically reviewed.
Safety first. Supplements can cause side effects and interact with medicines. Read mushroom safety and interactions before you use any mushroom product.
Read this first. The best-documented harm on this page is star anise tea given to infants, where a look-alike plant with neurotoxins was found in the supply. Case reports describe neurologic reactions including seizure-like episodes. For a suspected poisoning in the US call Poison Help at 1-800-222-1222, and call 911 for a seizure, trouble breathing or loss of consciousness. See poisoning: what to do first. [1][2]
In this page, adulteration means a product contains something other than what was intended, such as a look-alike plant or a contaminant, and mislabeling means the label does not match the contents. How often either happens to herbal teas on shelves is not known from the sources we read. We name no brands.
What has been documented
| Problem | What the source found | Strength of evidence | Form and population |
|---|---|---|---|
| Look-alike substitution | A US case series reported 7 infants with adverse neurologic reactions after home use of star anise tea, and found evidence that Chinese star anise (Illicium verum) had been contaminated with Japanese star anise (Illicium anisatum), which has documented neurologic and gastrointestinal toxicity. [1] A French case report of a 2-month-old links the cause of such poisonings in most cases to that contamination, citing the close macroscopic resemblance and the sale of fruits partly broken or ground. [2] | Case reports | Infants; tea made from whole spice |
| Does the label match the contents? | A study of 15 commercial herbal tea products used DNA metabarcoding and, on average, identified 70% (range 44 to 100) of the declared ingredients. The authors say fraud and adulteration are widespread issues. [3] | Method study; not a measure of how often labels are wrong | 15 products |
| Mold on tea | In 166 teas sold in Latvia (140 Camellia sinensis and 26 herbal), 87% tested positive for fungal species, and 42% carried 1 to 16 mycotoxins (toxins made by molds). The authors' exposure assessment concluded the teas were safe for consumers, assuming full transfer into the cup. [4] | Survey of samples | Dry tea |
| Mold toxins in the drink | In 52 ready-to-drink herbal tea beverages (including chamomile, linden, pennyroyal mint, thyme, valerian and horsetail), several mycotoxins were detected; pennyroyal mint and thyme had the highest levels; as we read the abstract, the authors' risk assessment did not identify a risk from drinking them. [5] | Survey of samples | Beverages; authors based in Spain |
| What favors mold? | A review says mycotoxin production by tea fungi is induced by factors including poor processing and high temperature and humidity. [6] | Review | Tea supply chain |
| Natural plant toxins | In a project analyzing 221 herbal tea, tea and herb samples, the German BfR reported first results of pyrrolizidine alkaloids (PAs, natural plant compounds that can damage the liver) from 0 to 3.4 mg per kg of dry product in the tested herbal tea and tea samples. [7] A 2026 study of 203 rooibos samples from 18 European countries detected PAs in 98% of them, and the mold toxin tenuazonic acid in all. [8] The EU herbal medicines committee (HMPC, 2016) notes PA-containing weeds contaminate raw materials used in food and herbal medicines. [9] | Survey of samples; regulator opinions | Dry tea |
For how plant-based PA tea hazards arise from the plants themselves, such as comfrey and coltsfoot, see comfrey, coltsfoot and pyrrolizidine alkaloid teas.
What the sources do not show
- How common mislabeling is on store shelves: Proper evidence not found. We searched PubMed on 2026-10-23 for "herbal tea mislabeled undeclared ingredient case" and "herbal tea samples label ingredients not declared DNA" and found no records; "adulteration herbal tea authenticity DNA" returned 14 records, and the titles we read were mostly authentication methods for single plants. [10]
- Undeclared drugs in herbal teas: NCCIH says the FDA has found prescription drugs in products sold as dietary supplements. [11] That statement is not specific to teas. See Detox, slimming and laxative teas.
- Any "safe batch" signal: the BfR notes PA content varies considerably, even within the same tea variety. [7]
Frequently asked questions
Can herbal tea contain mold?
Yes, in surveys. A Latvian study found fungal species in 87% of 166 teas, including herbal teas, and mycotoxins in 42%. [4] The authors' exposure assessment judged the teas safe for consumers under their assumptions. [4]
Is star anise tea safe for babies?
The authors of a US case series said star anise tea should no longer be given to infants because of its potential danger. [1] Ask a pediatric clinician.
Can I tell by looking whether a tea is adulterated?
The French case report says chemical analysis is required in most cases to detect adulteration of star anise. [2] This page does not offer identification instructions.
How do laboratories check what is in a tea?
One study used DNA metabarcoding with two DNA markers and identified, on average, 70% of the ingredients declared on 15 products; the authors describe it as a step toward quality control. [3]
What are pyrrolizidine alkaloids in tea?
Natural plant compounds. The BfR says certain ones can cause acute liver damage in high doses and some have proven to be genotoxic carcinogens in animal studies. [7]
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.
What the regulators and risk assessors said about PAs
- The BfR said that short-term intake (up to 14 days) is improbable to pose a health risk to adults and children, but that for people who frequently drink large amounts of tea with high PA content there is a risk of health impairment, particularly for children, pregnant women and breastfeeding mothers. [7]
- It advised parents not to offer children herbal teas and tea exclusively, and pregnant and breastfeeding women to vary their drinks. [7]
- The 2026 rooibos study reported mean and median total PA levels of 47 and 33 micrograms per kg; preliminary estimates suggested limited risk at mean contamination, while highly contaminated samples may contribute significantly to cumulative exposure. [8]
Safety and who should ask a clinician
- Infants and children. Case reports of star anise tea relate to infants. [1] The BfR advises not offering children herbal teas exclusively. [7] Ask a pediatric clinician before giving any herbal tea to a baby, and see children and teens.
- Pregnancy and breastfeeding. The BfR names these groups as most at risk from long-term high-PA tea consumption. [7] See pregnancy and breastfeeding.
- Liver. PAs are described as potentially causing acute liver damage in high doses. [7] See liver safety.
- Identification. This page does not teach how to identify plants. For wild or look-alike plants, contact poison help and a local expert such as a botanist or extension service.
- Report problems through side effects and reporting. Storage and mold basics are on storing herbal tea.
References
- Ize-Ludlow D, et al. Neurotoxicities in infants seen with the consumption of star anise tea. Pediatrics. 2004;114(5):e653-6. Case series. PubMed 15492355. Abstract read 2026-10-23.
- Perret C, et al. Apparent life-threatening event in infants: think about star anise intoxication! Arch Pediatr. 2011;18(7):750-3. Case report (abstract in English). PubMed 21652187. Abstract read 2026-10-23.
- Frigerio J, et al. DNA-Based Herbal Teas' Authentication: An ITS2 and psbA-trnH Multi-Marker DNA Metabarcoding Approach. Plants (Basel). 2021. PubMed 34685929. Abstract read 2026-10-23.
- Reinholds I, et al. Determination of Fungi and Multi-Class Mycotoxins in Camelia Sinensis and Herbal Teas and Dietary Exposure Assessment. Toxins (Basel). 2020. PubMed 32872457. Abstract read 2026-10-23.
- Pallarés N, et al. Occurrence of Mycotoxins in Botanical Dietary Supplement Infusion Beverages. J Nat Prod. 2019;82(2):403-406. PubMed 30688071. Abstract read 2026-10-23.
- Pandey AK, et al. Mycotoxins along the tea supply chain: A dark side of an ancient and high valued aromatic beverage. Crit Rev Food Sci Nutr. 2023. Review. PubMed 35452322. Abstract read 2026-10-23.
- German Federal Institute for Risk Assessment (BfR). Pyrrolizidine alkaloids in herbal teas and teas, BfR Opinion No. 018/2013, 5 July 2013. Read 2026-10-23.
- Volkov A, et al. Occurrence of tropane alkaloids, pyrrolizidine alkaloids and mycotoxins in rooibos: a comprehensive safety assessment. Food Addit Contam Part A. 2026. PubMed 42615889. Abstract read 2026-10-23.
- European Medicines Agency, Committee on Herbal Medicinal Products (HMPC). Public statement on contamination of herbal medicinal products/traditional herbal medicinal products with pyrrolizidine alkaloids: transitional recommendations for risk management and quality control, EMA/HMPC/328782/2016, adopted 31 May 2016. Read 2026-10-23.
- National Library of Medicine. PubMed, searched through the NCBI E-utilities on 2026-10-23. Queries and record counts are listed in the evidence log.
- National Center for Complementary and Integrative Health (NIH). Using Dietary Supplements Wisely. Last updated January 2019. Read 2026-10-23.