Drug & supplement interaction

Tansy Ragwort + Ondansetron

Ondansetron brand name: Zofran.

No Known Interaction
Medically reviewed by · Updated July 2026 · Pair last verified Sep 20, 2026
The bottom line No known interaction

We found no known interaction between Tansy Ragwort and Ondansetron in our sources. Absence of a documented interaction is not the same as proven safety, and does not guarantee one does not exist. Do not start, stop, or change a medication or supplement based on this page; confirm with your pharmacist or doctor first. Additionally, although there is no interaction, the two are separately associated with some of the same side effects, which would make a new symptom harder to attribute to one or the other.

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Interaction report

Tansy Ragwort and Ondansetron

We checked these two against our interaction database. Here is what we found.

No Known Interaction Found

We did not find a documented interaction between Ondansetron and Tansy Ragwort in our sources. This does not guarantee that the combination is completely free of risk — there is often limited research on supplements and herbal products, especially around drug interactions.

If you decide to take both, the practical routine is simple: add one new thing at a time and note the date you started it. If the combination is going to disagree with you, it usually shows in the first days to a couple of weeks — and a start date turns “I’ve been feeling off” into something a pharmacist can actually work with. Do not stop a prescribed medicine on your own.

Always talk with your pharmacist or doctor before making changes to your medications or supplements, particularly if you take several medications or have an ongoing health condition.

Tansy Ragwort safety at a glance

Tansy Ragwort overall Avoid It contains liver-toxic pyrrolizidine alkaloids and should not be taken internally.
Pregnancy Likely Unsafe When used orally. Tansy ragwort preparations containing hepatotoxic pyrrolizidine alkaloid (PA) constituents might be teratogenic and hepatotoxic. There is insu... Read the full pregnancy detail
Breastfeeding Likely Unsafe When used orally. Hepatotoxic pyrrolizidine alkaloid (PA) constituents in tansy ragwort are excreted in milk. There is insufficient reliable information availab... Read the full breastfeeding detail

Pregnancy & breastfeeding ratings are from Natural Medicines (Therapeutic Research Center) — the full detail is in the Special populations card below. Safety guidance is general; always confirm with your pharmacist or doctor for your situation.

Still wondering about combining Ondansetron and Tansy Ragwort? Ask Dr. Brian Staiger, PharmD, BCPS directly ›
How we checked

Why No Interaction Is Listed for Ondansetron

Interactions in our licensed database are recorded against drug classes, not just single drug names. Ondansetron is filed under 7 classifications — including serotonergic drugs, serotonergic drugs, cytochrome p450 1a2 (cyp1a2) substrates. Tansy Ragwort has documented interactions with 1 drug class — the most serious being cytochrome p450 3a4 (cyp3a4) inducers (moderate) — and none of Ondansetron’s classifications are among them.

Classification data comes from our licensed Natural Medicines dataset. A medication can belong to classes beyond those recorded there, so this describes how the check was run — it is not a safety guarantee.

Keep it in perspective

Tansy Ragwort Does Interact With Other Medications

Tansy Ragwort has 87 moderate known drug interactions in our database — Ondansetron isn’t one of them. If you take anything else, check it against the full list below.

Moderate 87 No known interaction 2,743 (incl. Ondansetron)
Taking anything else?

Check Another of Your Medications Against Tansy Ragwort

Covers the 2,830 medications we’ve checked against Tansy Ragwort. Pick one to open its full report.

What to actually watch for

No Interaction Found — But Data Suggests Tansy Ragwort and Ondansetron May Share a Side Effect

This is not an interaction. Neither one changes how your body handles the other, and nothing here says they react together. What our sources do show is that each has separately been linked to the effects below — so taking both can make those effects more likely to turn up, and harder to pin on one or the other if they do. One of them is worth acting on rather than waiting out — marked below.

  • Raised blood pressure Worth acting on Additional detail

    Tansy Ragwort

    “Orally, the major concern with tansy ragwort use is its pyrrolizidine alkaloid (PA) content. These constituents can cause lung damage with pulmonary-arterial hypertension.”

    Tansy Ragwort · Natural Medicines adverse-effect record, reported in hypertension.

    2 sources cited
    1. 12841. Chojkier M. Hepatic sinusoidal-obstruction syndrome: toxicity of pyrrolizidine alkaloids. J Hepatol 2003;39:437-46. PubMed
    2. 12842. Roeder E. Medicinal plants in Europe containing pyrrolizidine alkaloids. Pharmazie 1995;50:83-98.

    Ondansetron

    Listed in the ADVERSE REACTIONS section of the FDA label for Ondansetron. Read the label on DailyMed ›

Reported for Tansy Ragwort but not commonly for Ondansetron: vomiting and diarrhea.

Effects for Ondansetron come from the ADVERSE REACTIONS section of its FDA label; effects for Tansy Ragwort come from the Natural Medicines adverse-effect record, quoted above. Where a percentage is shown, it is the share of 121,840 voluntary FDA FAERS reports for Ondansetron that mention that effect — a reporting proportion, not an incidence rate and not evidence the drug caused it. Wording is matched across sources by our own clinical vocabulary, so treat this as a prompt to pay attention, not a diagnosis.

Special populations

Tansy Ragwort in Pregnancy & Breastfeeding

Pregnancy Likely Unsafe

When used orally. Tansy ragwort preparations containing hepatotoxic pyrrolizidine alkaloid (PA) constituents might be teratogenic and hepatotoxic. There is insufficient reliable information available about the safety of using tansy ragwort products that do not contain hepatotoxic PAs during pregnancy.

Lactation Likely Unsafe

When used orally. Hepatotoxic pyrrolizidine alkaloid (PA) constituents in tansy ragwort are excreted in milk. There is insufficient reliable information available about the safety of using tansy ragwort products that do not contain hepatotoxic PAs during lactation.

DISCLAIMER: This tool is intended for informational purposes only, and should not be interpreted as specific medical advice. Patients should consult with a qualified healthcare provider before making decisions about therapies and/or health conditions.© 2026 Therapeutic Research Center

From our Q&A

Questions About Tansy Ragwort or Ondansetron

These are real questions from readers, answered by the pharmacists at HelloPharmacist — written by a person, not generated from a database. Each one covers Tansy Ragwort or Ondansetron, not necessarily both, but if one is close to what you were about to ask it will usually go further than a database entry can:

Not quite your question? Ask our pharmacists directly — it is free, there is no account required, and answers usually come back within 24 hours.

Everything else you take

See Every Supplement That Interacts With Ondansetron

This page covers Tansy Ragwort only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Ondansetron page lists 195 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), Grapefruit (major), Lithium (major), St. John's Wort (major) and 1,3-dmaa (moderate).

By severity: 4 major · 145 moderate · 46 minor.

From our pharmacist’s overview on the Ondansetron page

“Ondansetron (Zofran) often stands between you and relentless nausea from chemotherapy or surgery, so read this page carefully. Four of the 195 ingredients rate major.”

Reviewed by 2 · Jul 18, 2026

Open the Ondansetron interaction page

How much people look this up

Where Tansy Ragwort and Ondansetron Sit Against Everything Else

Out of every supplement and medication people look up on HelloPharmacist, here is where these two land this week — and which way each has been moving.

Supplement Tansy Ragwort
Steady interest

#825 of 1,452 supplements looked up here in the last 7 days

29 days ago today
Medication Ondansetron
Steady interest

#1,687 of 2,830 medications looked up here in the last 7 days

29 days ago today

Position among everything looked up on this site, not a measure of how commonly either one is used or how important it is. A supplement can climb this list because of a news story. It counts every request to the page, automated ones included, and nothing here identifies anyone.

Where does our data come from?
  • Source: the Natural Medicines (TRC Healthcare) clinical database — the evidence-graded professional reference for herb & supplement interactions.
  • Citation library: 103,510 references behind our interaction content, 65,311 of them resolved to verified PubMed/DOI sources. See every Tansy Ragwort reference on this page ↓
  • Freshness: we automatically re-check this combination every week — this pair was last verified September 20, 2026. The Tansy Ragwort and Ondansetron records this page draws on were last updated July 11, 2026.
  • What “no known interaction” means: no documented interaction in the sources above — not a guarantee of safety. Supplements are studied far less than prescription drugs, so we say exactly what the evidence supports, and nothing more.
Data structure & sourcing designed and verified by .
Supplement

About Tansy Ragwort

What is Tansy Ragwort?

  • Traditional wound and skin washes
  • Folk remedy for sore throat (gargle)
  • Topical poultice for joint or muscle aches
  • Historical use for menstrual complaints

Tansy ragwort is a toxic weed that contains pyrrolizidine alkaloids, which can seriously damage the liver. It is not recommended as a supplement or home remedy, and there is no reliable evidence that it safely treats any condition. Avoid taking it internally and talk to a pharmacist or doctor before using any herbal product.

Jacobaea vulgaris · Asteraceae · Aerial parts (leaves, flowers, stems) · Rarely sold as a supplement; historically used as a tea, poultice, or topical wash

An interaction check asks whether these two react with each other — it does not ask whether Tansy Ragwort is a good idea for someone in your situation. Here is what our Tansy Ragwort record says about it on its own.

Tansy Ragwort: dosing

There is no safe or established dose for tansy ragwort. Because of its toxicity, no medical or pharmacy authority recommends an amount to take by mouth.If you see this plant listed in any product, do not assume it is safe.

From our Tansy Ragwort monograph — the full record covers uses, side effects and every documented interaction.

Read the full Tansy Ragwort monograph & all interactions
Medication

About Ondansetron

What Is Ondansetron Used For?

Brand name: Zofran

Ondansetron is used to prevent nausea and vomiting in several situations. Oral forms (tablets, orally disintegrating tablets, and oral solution) are approved to prevent nausea and vomiting from highly or moderately emetogenic (nausea-causing) cancer chemotherapy, from radiation therapy to the abdomen or whole body, and from surgery.

Ondansetron injection (given intravenously or intramuscularly in a clinical setting) is approved to prevent nausea and vomiting from emetogenic cancer chemotherapy — including high-dose cisplatin — in adults and children as young as 6 months old, as well as to prevent postoperative nausea and vomiting.

Most-Reported Side Effects for Ondansetron

From FAERS, the FDA’s public side-effect reporting system (121,840 reports, all brands). Reports are voluntary and are not proof the drug caused the effect.

Nausea 14,459 reports
Fatigue 10,275 reports
Diarrhea 9,488 reports
Vomiting 8,777 reports
Dyspnea 5,971 reports
See full Ondansetron drug information
Keep checking

Other Drugs & Tansy Ragwort

Browse every other medication we’ve checked against Tansy Ragwort — both the ones with a known interaction and the ones without. Select any drug for the full detail.

0Major
87Moderate
0Minor
2,742No known interaction
87 Moderate 2,742 No interaction
Moderate

87 interactions

Showing 60 of 87 moderate interactions — see all 87 on the Tansy Ragwort page.

No interaction 2,742 drugs checked — show the list

We also checked Tansy Ragwort against these medications and found no known interaction in our sources. Open any page to confirm.

Showing the 60 most looked-up of 2,742 medications checked with no known interaction — see the full Tansy Ragwort list.

See the full Tansy Ragwort interactions page
See every supplement checked against Ondansetron, ranked by severity
Evidence & sources

Tansy Ragwort References

The 4 references that drive our Tansy Ragwort monograph and interaction data, from the evidence-graded Natural Medicines (TRC Healthcare) database. Citations with a link open the study on PubMed or the publisher’s site.

  1. WHO working group. Pyrrolizidine alkaloids. Environmental Health Criteria, 80. WHO: Geneva, 1988.
  2. Chojkier M. Hepatic sinusoidal-obstruction syndrome: toxicity of pyrrolizidine alkaloids. J Hepatol 2003;39:437-46. PubMed
  3. Roeder E. Medicinal plants in Europe containing pyrrolizidine alkaloids. Pharmazie 1995;50:83-98.
  4. Wang YP, Yan J, Fu PP, Chou MW. Human liver microsomal reduction of pyrrolizidine alkaloid N-oxides to form the corresponding carcinogenic parent alkaloid. Toxicol Lett 2005;155:411-20. PubMed

Medication overviews come from MedlinePlus (NIH); supplement label data from the NIH Dietary Supplement Label Database. Content is written and reviewed by licensed HelloPharmacist pharmacists — see our data sources and editorial standards.

Pharmacist Counseling Corner

Taking Tansy Ragwort and Ondansetron Together: Common Questions

Is it safe to take Tansy Ragwort with Ondansetron?
We do not list a known interaction between Tansy Ragwort and Ondansetron. That does not guarantee the combination is risk-free, so confirm with your pharmacist or doctor — especially if you take other medications or have a health condition.
Do Tansy Ragwort and Ondansetron have any of the same side effects?
Yes — our sources link each of them separately to one of the same effects. That is not an interaction: neither changes how your body handles the other. It does mean that if one of those effects turns up, it can be harder to tell which one is behind it. They are listed on this page with the source behind each.
How was the Tansy Ragwort and Ondansetron combination checked?
Interactions in our licensed database are recorded against drug classes. Ondansetron is filed under 7 classifications, and Tansy Ragwort has documented interactions with 1 drug class — none of Ondansetron's classifications are among them. A medication can belong to classes beyond those recorded in our dataset, so this describes how the check was run rather than guaranteeing safety.
Does Tansy Ragwort interact with any other medications?
Yes. Tansy Ragwort has 87 documented drug interactions in our database — Ondansetron is simply not one of them. If you take anything else, it is worth checking each one; they are all listed on this page.
Does Ondansetron interact with any supplements?
Yes. Ondansetron has documented interactions with 195 supplements in our database — Tansy Ragwort is not one of them. The Ondansetron interaction page linked on this page lists every one, ranked by severity.

Written and reviewed by the HelloPharmacist editorial staff. Our editorial policy

Where next

Keep Exploring

Tansy Ragwort monograph Uses, safety profile, and every drug interaction in one place Ondansetron drug information The full plain-English guide to this medication Ondansetron supplement interactions Every supplement checked against Ondansetron, ranked by severity Supplement interaction checker Check any supplement or product against your medications Browse medications A–Z Every drug we’ve checked against herbs & supplements References The 4 citations behind this page Ask a pharmacist Free, personal answer from our licensed team

Still Have a Question About Ondansetron and Tansy Ragwort?

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This information is for education only and is not a substitute for professional medical advice. Always check with your pharmacist or doctor before starting, stopping, or combining supplements and medications.