Herbal Tea for People Taking Many Medicines
How to think about herbal tea if you take several medicines: what "documented", "reported" and "theoretical" mean, which teas sources flag, and how to prepare for a pharmacist visit.
Content last updated . This page has not been medically reviewed.
Safety first. Natural products can cause side effects and interact with medicines. Read herbal tea and extract safety before you use anything on this page.
Read this first
- Tell the pharmacist and prescriber about every tea. NIH says dietary supplements may interact with medications. [1] Herbal teas are among the forms herbal supplements are sold in. [1]
- St. John's wort is the clearest warning in the sources we read. NIH says it has been clearly shown that St. John's wort (Hypericum perforatum L.) can interact in dangerous, sometimes life-threatening ways with a variety of medicines. [2] It can weaken the effects of many medicines, including crucially important ones. [2] That NIH page covers the herb in general, not only tea.
- Never stop or change a prescribed medicine because of a tea. Ask the prescriber or pharmacist.
- If someone may have swallowed too much of a product, call Poison Help at 1-800-222-1222 (US), or 911 in an emergency.
Why many medicines change the question
The more medicines a person takes, the more combinations there are to check. Sources show that herbal products are part of that picture, though they usually do not separate teas from capsules.| Question | What the source found | Strength of evidence | Population and form |
|---|---|---|---|
| How often do supplements and medicines overlap? | In a hospital study, 458 of 927 patients (49%) reported dietary or herbal supplement use, and 215 of those had at least one potential interaction. [3] | Observational; potential interactions were identified by database lookup | Inpatients in Israel; supplements in general |
| Are they recorded? | Doctors documented only 16.5% of the supplements involved in those interactions. [3] | Observational | As above |
| Do clinicians ask? | A clinical review says physicians are often unaware that patients use herbal products alongside conventional medicines. [4] | Review | Older people |
| How common is polypharmacy? | 72.3% of 130 adults aged 60 or older at senior centers on the US-Mexico border met the study's polypharmacy definition. [5] | Descriptive survey | Older adults; all products |
Proper evidence not found for a trial that tested herbal tea against a set of medicines in people taking many of them. Our PubMed searches on herbal tea, herb-drug interactions and polypharmacy returned supplement surveys and reviews like those above, not tea trials.
Documented, reported, preliminary, theoretical
NIH uses different wording for different strengths of evidence, and so does our interactions guide. The table keeps NIH's words.| Tea plant | What NIH says | How strong the wording is |
|---|---|---|
| St. John's wort | Dangerous interactions with a variety of medicines have been clearly shown. [2] | Documented |
| Licorice (Glycyrrhiza glabra L.) | Interactions with corticosteroids have been reported. [6] Even small amounts of glycyrrhizin have been linked to severe adverse effects. [6] | Reported |
| Chamomile (Matricaria chamomilla L.) | Interactions with warfarin and some drugs processed by the liver have been reported; sedatives are a theoretical concern. [7] | Reported and theoretical |
| Valerian (Valeriana officinalis L.) | Should not be taken with alcohol or sedatives, because it might have a sleep-inducing effect (not proven). [8] | Possible |
| Passionflower (Passiflora incarnata L.) | Might interact with some anesthesia drugs; avoid before surgery unless a provider recommends it. [9] | Possible |
| Dandelion (Taraxacum officinale Weber ex F.H.Wigg.) | Theoretical interactions with antidiabetes, anticoagulant, antiplatelet and water pill drugs. [10] | Theoretical |
Plant names were checked against GBIF. [11] "Theoretical" means a reason to suspect an interaction, not proof of harm. It is also not proof of safety. Medicine groups to ask about include blood thinners, sedatives, diabetes medicines, water pills, corticosteroids, and medicines processed by the liver. For a longer list by medicine group, see interactions by drug class and herbal tea and medicine interactions.
Herb pages versus a cup of tea, and blends
NIH describes chamomile as likely safe in the amounts commonly found in teas, yet still notes reported interactions. [7] The NIH pages above describe the herb in general, not a single cup of tea, so they cannot tell you how much a cup matters. Blends make it harder: check the ingredient list for licorice, St. John's wort and sedating herbs. See reading an ingredient list and blends and what labels hide.How to prepare for a pharmacist visit
- Write down each tea, with the full ingredient list from the box, and how often you drink it.
- Bring all prescription, over-the-counter and supplement products.
- Ask: "Does any ingredient in this tea matter with my medicines, my kidneys or liver, or an upcoming procedure?"
- FDA advises talking to a doctor, pharmacist or other health professional before using a dietary supplement. [12]
- Before surgery, tell the surgical team about teas. See herbal tea before surgery.
Quality is a separate question. FDA says it is not authorized to approve dietary supplements for safety and effectiveness before they are marketed. [12] See product quality and contamination.
Frequently asked questions
Can I drink herbal tea if I take several medicines?
Possibly, but the answer depends on the tea and the medicines. Ask a pharmacist with your full list. NIH states that supplements may interact with medications. [1]
Which tea has the strongest interaction warning?
In the NIH pages we read, St. John's wort has the strongest wording ("clearly shown" dangerous interactions). [2] We do not rank teas for general safety.
What does "theoretical interaction" mean?
It means there is a reason to suspect an interaction, such as NIH's note that dandelion might interact with antidiabetes, blood-thinning and water pill drugs. [10] It is not proof of harm and not proof of safety.
Is my chamomile tea a problem with warfarin?
NIH says interactions between chamomile and warfarin have been reported. [7] Ask the prescriber or pharmacist before making it a regular habit, and do not change warfarin yourself.
Do pharmacists know about herbal teas?
Many can check an ingredient list against your medicines. A review found physicians are often unaware of patients' herbal product use, so raise it yourself. [4]
References
- National Center for Complementary and Integrative Health (NIH). Using Dietary Supplements Wisely. Read 2026-10-23.
- National Center for Complementary and Integrative Health (NIH). St. John’s Wort: Usefulness and Safety. Read 2026-10-23.
- Potential drug interactions with dietary and herbal supplements during hospitalization. Internal and Emergency Medicine. 2017. PubMed 27709322 (abstract; hospital inpatients in Israel, supplements in general, not teas only). Read 2026-10-23.
- Herbal medications and other dietary supplements. A clinical review for physicians caring for older people. Annals of Medicine. 2016. PubMed 27427263 (abstract). Read 2026-10-23.
- Prevalence of polypharmacy, polyherbacy, nutritional supplement use and potential product interactions among older adults living on the United States-Mexico border. Drugs & Aging. 2009. PubMed 19552494 (abstract; questionnaire study). Read 2026-10-23.
- National Center for Complementary and Integrative Health (NIH). Licorice Root: Usefulness and Safety. Read 2026-10-23.
- National Center for Complementary and Integrative Health (NIH). Chamomile: Usefulness and Safety. Read 2026-10-23.
- National Center for Complementary and Integrative Health (NIH). Valerian: Usefulness and Safety. Read 2026-10-23.
- National Center for Complementary and Integrative Health (NIH). Passionflower: Usefulness and Safety. Read 2026-10-23.
- National Center for Complementary and Integrative Health (NIH). Dandelion: Usefulness and Safety. Read 2026-10-23.
- GBIF Secretariat. GBIF Backbone Taxonomy species match (accepted names checked for the plants named on these pages). Read 2026-10-23.
- U.S. Food and Drug Administration. Information for Consumers on Using Dietary Supplements. Read 2026-10-23.