How to judge a cup of herbal tea, which is gentle but not automatically harmless

Key takeaways

• In a 2013 report, German food-safety scientists who tested 221 teas found plant toxins called pyrrolizidine alkaloids at levels up to 3,430 micrograms per kilogram, possibly from weeds harvested with the crop¹.
• Since July 2022, the European Union has set legal limits for those toxins in herbal teas, with the strictest limits for teas made for babies and young children².
• Evidence for popular teas is mostly early: chamomile for anxiety and hibiscus for blood pressure show promise, while peppermint tea itself has barely been studied⁸⁹¹¹.
• Licorice root may raise blood pressure, St. John’s wort weakens many prescription drugs and senna is a stimulant laxative, so check with a clinician before using them regularly¹¹¹³¹⁴.
• Read the label for the plant’s scientific name and the part used, and treat “detox” or disease-cure claims as a reason to walk away⁶¹⁵.

In 2013, Germany’s Federal Institute for Risk Assessment published the results of a shopping trip. Researchers had bought 221 teas from Berlin food stores and pharmacies, including chamomile, peppermint, fennel, lemon balm and teas sold for babies¹.

Many contained pyrrolizidine alkaloids, or PAs: natural plant compounds that can harm the liver in high doses and are treated as possible cancer-causing agents over the long term¹. Levels ranged from none at all to 3,430 micrograms per kilogram of dry tea. Chamomile and lemon balm had the highest averages¹.

The surprising part was the likely source. The scientists didn’t blame the chamomile. Their leading explanation was PA-containing wild weeds growing in the same fields and getting harvested along with the crop¹.

That finding gets to the heart of judging an herbal tea. The tradition is sound and the plant may be gentle. But what reaches your cup depends on which plant it is, which part, what grew next to it, how strong you brew it and what else you take.

This guide shows you how to judge each of those, while keeping the pleasure of a good cup intact.

The weeds in the field matter as much as the herb

Europe acted on findings like Germany’s. Starting July 1, 2022, the European Union set legal maximum levels for PAs in tea and herbal infusions².

The limits are measured in micrograms per kilogram of dried product:

Product	EU maximum for PAs
Most dried herbal teas	200
Chamomile, peppermint, rooibos, lemon balm, anise, thyme, lemon verbena	400
Black and green tea	150
Teas and herbal teas for infants and young children, dried	75
Same infant products, ready to drink (liquid)	1

The EU explained why. Europe’s food-safety authority had concluded that tea and herbal infusions are the main sources of PA exposure for people. It flagged a possible concern for frequent, heavy tea drinkers and for younger people². The rule also notes that better farming and harvest practices can keep PAs down².

We found no comparable U.S. limit for PAs in tea. That doesn’t mean American tea is worse. It means the burden of asking falls more on you and on the companies you buy from.

The German scientists’ advice was practical: vary your teas rather than drinking one kind all day, and don’t give children herbal tea as their only drink¹. They also urged producers to test batches before sale¹. That gives you a fair question for any tea company: “Do you test your herbs for pyrrolizidine alkaloids?”

One herb is a PA source by nature, not by accident. Comfrey contains PAs, and the FDA issued a safety communication about comfrey products in July 2001⁴. Comfrey tea is one to skip.

Food or supplement? The label decides more than you’d think

In the U.S., an herbal tea can be sold as a regular food or as a dietary supplement. Neither needs FDA approval before it goes on sale.

The FDA decides which one a product is by looking at the whole package: its name, packaging, serving size, directions and marketing³. Its 2014 guidance notes that the word “tea” can fit either category, so the name alone doesn’t settle it³. A product sold to refresh or quench thirst is generally a food, even if the label calls it a supplement³.

Why it matters to you: a tea labeled as a supplement carries a Supplement Facts panel, which tells you more about its dose. A tea sold as food carries an ingredient list, and the box may say little about strength.

Claims matter too. The Federal Trade Commission requires health claims to be backed by competent and reliable scientific evidence, generally human clinical trials⁵. Its guidance includes a telling example: a traditional claim like “used for centuries to aid digestion” can still mislead if a glowing testimonial next to it promises instant relief⁵.

Strength: a cup, a tincture and an oil are different doses

The same plant can show up in very different strengths. Concentrated forms pack a plant into far less liquid or powder: according to the NIH Office of Dietary Supplements, what’s in one cup of tea can match a few teaspoons of tincture, and an extract shrinks it further still⁶.

Peppermint shows why this matters. A cup of the tea is usually fine to drink, but the oil is much more concentrated and can be toxic when used the wrong way⁶.

Preparation also changes what you get. Leaves and flowers are usually steeped in hot water. Tougher parts, like many roots, bark and berries, are often simmered into a stronger brew called a decoction⁶.

The FTC has made the same point about concentrates. Its guidance says a long history of brewing a raw plant as tea does not vouch for a concentrated extract of that plant⁵. The tradition belongs to the cup.

For a sense of a traditional dose, Europe’s medicines agency lists 1.5 to 4 grams of dried chamomile flowers in 150 milliliters (about 5 ounces) of boiling water, three to four times a day, for adults with minor stomach complaints⁷. For children ages 6 months to 2 years, it lists 0.5 to 1 gram, two to four times a day⁷.

What the evidence says about popular teas

Most research on herbs tests capsules or extracts, not the tea in your mug. Keep that in mind as you read the ratings below.

Tea and use	What research shows	Rating
Chamomile for anxiety	Early studies, mostly of chamomile supplements, suggest it may ease generalized anxiety8	Promising but early
Chamomile for sleep	A 2019 review found only one insomnia study, and it showed no benefit8	Not enough evidence
Chamomile for minor stomach upset	Europe registers it as a traditional use based on long-standing use, not trials7	Not enough evidence
Peppermint tea for digestion	Very little research on peppermint leaf exists9	Not enough evidence
Peppermint oil capsules for irritable bowel syndrome	A 2022 review of 10 studies with 1,030 people found benefit over placebo9	Strong evidence, for capsules, not tea
Ginger for nausea in pregnancy	Research suggests it may help; most studies used supplements10	Promising but early
Ginger for motion sickness	Most studies have not found it helpful10	Evidence says no
Hibiscus for high blood pressure	Limited evidence of a small effect11	Promising but early
Licorice root for any condition	Not enough high-quality evidence for any use12	Not enough evidence
“Detox” teas for weight loss	The FTC charged one major seller with lacking reliable evidence15	Not enough evidence

A note on hibiscus: NCCIH says no supplement lowers blood pressure as much as prescription drugs do¹¹. If you have high blood pressure, a daily cup can be part of your routine, not a replacement for treatment your clinician prescribed.

Teas with real cautions, and who should check first

Most herbal teas are low-risk for most adults. A few herbs deserve respect.

Herb	What can go wrong	Talk to a clinician first if you…
Licorice root	Its compound glycyrrhizin, in large amounts or with long use, has been linked to irregular heartbeat and cardiac arrest; licorice may also raise blood pressure1112	have high blood pressure, heart or kidney disease, eat a lot of salt, take steroid medicines or are pregnant
St. John’s wort	Weakens many medicines, including birth control pills, warfarin, some antidepressants and some HIV, heart, transplant and cancer drugs13	take any prescription medicine or are pregnant
Senna	A stimulant laxative; long or frequent use can make you dependent on laxatives14	need it for more than a week, are pregnant or breastfeeding, or are 65 or older
Chamomile	Allergic reactions, rarely severe; interactions with warfarin have been reported8	are allergic to ragweed, daisies, marigolds or chrysanthemums, or take warfarin
Comfrey	A natural source of PAs; subject of a 2001 FDA safety communication4	Skip it entirely

Some licorice products remove glycyrrhizin and are labeled DGL, which NCCIH says might be safe for up to four months¹².

If you find St. John’s wort in a tea blend, remember that NCCIH’s interaction warnings don’t carve out the tea form¹³. Treat a daily cup the way you would a capsule, and tell your pharmacist.

Pregnancy. NCCIH warns that heavy licorice use, about 250 grams of licorice a week, is unsafe in pregnancy and raises the risk of early delivery¹². It says St. John’s wort may be unsafe in pregnancy¹³. For chamomile, NCCIH says little is known about safety in pregnancy⁸, while Europe’s medicines agency considers the plain dried flower safe in pregnancy and breastfeeding⁷. When expert bodies disagree, ask your prenatal clinician.

Babies and children. The German scientists advised parents not to give children herbal tea as their only drink¹. Europe’s strictest PA limits apply to teas made for infants and young children². Ask your pediatrician before giving any herbal tea to a baby.

“Detox” and “skinny” teas: what one federal case showed

In March 2020, the FTC announced a case against Teami, a company that promoted its teas through celebrity Instagram posts¹⁵. The agency said Teami claimed, without reliable scientific evidence, that its 30 Day Detox Pack helped people lose weight¹⁵.

The FTC also said Teami claimed its other teas fought cancer, cleared clogged arteries, reduced migraines and treated or prevented colds and flu¹⁵. Posts by paid influencers, including Cardi B and Jordin Sparks, hid the disclosure that they were paid unless followers clicked “more”¹⁵.

The court order included a $15.2 million judgment, equal to Teami’s sales of the challenged products. The FTC agreed to suspend it once the company paid $1 million, because it couldn’t afford the rest¹⁵.

Check the ingredient list on any “detox” or “slimming” tea. If it includes senna, you are drinking a stimulant laxative, the same plant used in over-the-counter laxatives¹⁴. MedlinePlus advises not taking senna for more than a week without talking to a doctor, and to stop and call a doctor if you have rectal bleeding¹⁴.

How to read an herbal tea label

Use this checklist in the store or on a shopping site. Every “no” is a question to ask the seller.

• Scientific name. Does the box name the species, not just “chamomile”? Europe’s chamomile standards, for example, cover Matricaria recutita, or German chamomile⁷⁸.
• Plant part. Does it say flower, leaf, root or seed? The part changes the chemistry and the brewing method⁶.
• Food or supplement. Is it labeled as a dietary supplement with a Supplement Facts panel, or as a food with an ingredient list³?
• Hidden heavy hitters. Scan blends for licorice root, senna, St. John’s wort or comfrey.
• Caffeine. “Herbal” blends sometimes include green or black tea, which contain caffeine.
• Claims. Words like “detox,” “flushes fat,” “cures” or “treats” are red flags¹⁵.
• Traceability. Is there a lot number, a best-by date and a company you can contact?
• Testing. Will the seller tell you whether it tests for PAs¹, and for pesticides and heavy metals?
• Kids’ teas. Is a tea marketed for babies? Ask your pediatrician before using it².

Tradition counts, and so does the evidence

People have steeped plants in hot water for a very long time, and that history deserves respect. Europe gives it a formal role: its medicines agency registers chamomile flower as a traditional herbal medicine for minor complaints, based on long-standing use rather than clinical trials⁷.

That approach honors tradition without pretending it is the same as proof. It also keeps the tradition tied to the gentle form people used: a cup of tea, not a concentrated pill⁵.

You can do the same. Enjoy the ritual, choose plants from sellers who know their fields, and save your skepticism for the box that promises a cure.

When to get help

Stop drinking a tea and call your clinician if you notice a racing or irregular heartbeat, swelling, new muscle weakness, a rash or hives, or digestive trouble that won’t quit. Tell every clinician and pharmacist which herbal teas you drink regularly, especially before surgery or a new prescription.

Call 911 for trouble breathing, swelling of the face or throat, chest pain or fainting. For a child who drank a large amount of an herbal product, call Poison Control at 1-800-222-1222.

You can report a problem with a tea sold as a supplement to the FDA’s Safety Reporting Portal at safetyreporting.hhs.gov. Report misleading health claims to the FTC at ReportFraud.ftc.gov.

Questions readers ask

The bottom line

Herbal tea is still one of the gentlest ways to use plants, and for most adults most teas are low-risk. But “gentle” depends on details: the right species and part, a clean harvest, a sensible strength and no clash with your medicines.

Read the label for the scientific name and plant part, rotate your teas, be cautious with licorice, St. John’s wort and senna, and skip comfrey. Treat promises to detox, slim or cure as the clearest sign that a seller cares more about the sale than the cup.

Related reading

• Why “natural” on a food label guarantees almost nothing
• What gets into supplements that isn’t on the label
• What happens when you don’t tell your doctor about supplements
• The four USDA organic labels and what each one promises
• A supplement brand can outsource the making, not the responsibility

Sources

1. German Federal Institute for Risk Assessment (BfR). “Pyrrolizidine Alkaloids in Herbal Teas and Teas.” BfR Opinion No. 018/2013, July 5, 2013. bfr.bund.de
2. European Commission. “Commission Regulation (EU) 2020/2040 Amending Regulation (EC) No 1881/2006 as Regards Maximum Levels of Pyrrolizidine Alkaloids in Certain Foodstuffs.” Official Journal of the European Union, 2020. eur-lex.europa.eu
3. U.S. Food and Drug Administration. “Guidance for Industry: Distinguishing Liquid Dietary Supplements from Beverages.” FDA, January 2014. fda.gov
4. U.S. Food and Drug Administration. “Information on Select Dietary Supplement Ingredients and Other Substances.” FDA, 2026. fda.gov
5. Federal Trade Commission. “Health Products Compliance Guidance.” FTC, December 2022. ftc.gov
6. NIH Office of Dietary Supplements. “Botanical Dietary Supplements: Background Information.” National Institutes of Health, 2020. ods.od.nih.gov
7. European Medicines Agency, Committee on Herbal Medicinal Products. “European Union Herbal Monograph on Matricaria recutita L., flos.” EMA, adopted July 7, 2015. ema.europa.eu
8. National Center for Complementary and Integrative Health. “Chamomile.” NIH, November 2024. nccih.nih.gov
9. National Center for Complementary and Integrative Health. “Peppermint Oil.” NIH, May 2025. nccih.nih.gov
10. National Center for Complementary and Integrative Health. “Ginger.” NIH, February 2025. nccih.nih.gov
11. National Center for Complementary and Integrative Health. “High Blood Pressure and Complementary Health Approaches.” NIH, July 2018. nccih.nih.gov
12. National Center for Complementary and Integrative Health. “Licorice Root.” NIH, April 2025. nccih.nih.gov
13. National Center for Complementary and Integrative Health. “St. John’s Wort.” NIH, May 2025. nccih.nih.gov
14. MedlinePlus. “Senna.” National Library of Medicine, revised June 20, 2024. medlineplus.gov
15. Federal Trade Commission. “Tea Marketer Misled Consumers, Didn’t Adequately Disclose Payments to Well-Known Influencers, FTC Alleges.” FTC, March 6, 2020. ftc.gov