Drug & supplement interaction

Tansy Ragwort + Ethosuximide

Ethosuximide brand name: Zarontin.

Moderate Interaction
Medically reviewed by · Updated September 2026
The bottom line Moderate

Tansy Ragwort has a moderate interaction with Ethosuximide. Theoretically, CYP3A4 inducers might increase the risk of adverse effects from the pyrrolizidine alkaloid (PA) constituents in tansy ragwort.

Read the full interaction report
SeverityModerate
LikelihoodPossible
EvidenceD
What do Severity, Likelihood & Evidence mean?
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Interaction report

Tansy Ragwort and Ethosuximide

Here is the interaction we found between these two, with the evidence behind it.

Moderate

CYTOCHROME P450 3A4 (CYP3A4) INDUCERS

Why this applies to Ethosuximide

Ethosuximide falls under CYTOCHROME P450 3A4 (CYP3A4) INDUCERS — the group Tansy Ragwort interacts with.

Theoretically, CYP3A4 inducers might increase the risk of adverse effects from the pyrrolizidine alkaloid (PA) constituents in tansy ragwort.
Tansy ragwort contains PAs. PAs are substrates of CYP3A4. Theoretically, drugs that induce CYP3A4 might increase the conversion of PAs to toxic metabolites.
Severity Moderate Likelihood Possible Evidence D

Interaction has been documented in animal or in lab research, or the interaction has been documented in humans but is limited to case reports or conflicting clinical research exists.

Dr. Brian Staiger, PharmD, BCPS
Dr. Brian Staiger explains PharmD, Clinical Pharmacist

Here's the honest starting point: tansy ragwort isn't something you should be taking at all. It contains pyrrolizidine alkaloids that can poison your liver, even on their own. So my real advice is to skip it entirely.

As for the interaction itself, ethosuximide can mildly speed up a liver enzyme called CYP3A4. That same enzyme is what turns tansy ragwort's compounds into the toxic forms that harm liver cells. So in theory, taking them together could make the plant's poison hit a little harder. This is a theoretical concern based only on lab and animal data, not on cases in people, so I don't want to scare you. Ethosuximide itself isn't the danger here, the weed is. Please talk with your pharmacist or doctor before using any herbal product.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Chojkier M. Hepatic sinusoidal-obstruction syndrome: toxicity of pyrrolizidine alkaloids. J Hepatol 2003;39:437-46. PubMed
  2. 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

What These Ratings Mean

Every interaction above is graded three ways — here’s the key to each label.

Severity how clinically significant the interaction is
Major

Clinically significant. Avoid the combination, or use only under close professional supervision.

Moderate

Usually worth avoiding or managing — may need monitoring, a dose change, or timing apart.

Minor

Generally not serious. Be aware of it and mention it to your pharmacist.

Likelihood how strong the evidence is that the interaction actually happens in people
  • LikelyWell-controlled human studies have demonstrated the likely existence of this interaction.
  • ProbableInteraction has not been documented in well-controlled studies, however, the interaction has been demonstrated in some small human studies or in controlled animal studies in conjunction with multiple case reports.
  • PossibleInteraction has been documented in animal or in lab research, or the interaction has been documented in humans but is limited to case reports or conflicting clinical research exists.
  • UnlikelyInteraction has been demonstrated in animal or in lab research but has been shown not to occur in humans.
Evidence the quality of the studies behind the rating (graded A–D)
  • AHigh-quality meta-analysis (quantitative systematic review).
  • BCase-control study.
  • CConsensus.
  • DAnecdotal evidence.

These ratings are for information only. Never start, stop, or otherwise change your therapy before speaking with your provider.

Keep it in perspective

Tansy Ragwort Also Interacts With Other Medications

Tansy Ragwort has 86 moderate known drug interactions in our database — the Ethosuximide one above is one of them. If you take anything else, check it against the full list below.

Moderate 86 No known interaction 2,744 (incl. Ethosuximide)
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.

Everything else you take

See Every Supplement That Interacts With Ethosuximide

This page covers Tansy Ragwort only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Ethosuximide page lists 226 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: 1,4-butanediol (major), Activated Charcoal (major), Beer (major), Gamma-hydroxybutyrate (ghb) (major) and Grapefruit (major).

By severity: 9 major · 179 moderate · 38 minor.

From our pharmacist’s overview on the Ethosuximide page

“Ethosuximide (Zarontin) prevents absence seizures, and a steady blood level is what keeps them away, so I treat this list of 226 interacting supplements and herbs with real care, especially the nine rated major. More than half of the entries can change how the liver clears the drug; grapefruit can raise its level while St.”

Reviewed by 2 · Jul 18, 2026

Open the Ethosuximide interaction page

How much people look this up

Where Tansy Ragwort and Ethosuximide 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

#1,058 of 1,452 supplements looked up here in the last 7 days

29 days ago today
Medication Ethosuximide
Steady interest

#2,285 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.

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.

Read the full Tansy Ragwort monograph & all interactions
Medication

About Ethosuximide

What Is Ethosuximide Used For?

Brand name: Zarontin

Ethosuximide — sold as Zarontin and also available as generic Ethosuximide — is used to control absence (petit mal) epilepsy. Absence seizures are brief episodes where a person loses awareness for a few seconds, often mistaken for daydreaming.

Both Zarontin and Ethosuximide products (capsule and oral solution forms) are approved for this use. Either may also be used alongside other seizure medicines when a patient has absence seizures together with other types of epilepsy.

See full Ethosuximide 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
86Moderate
0Minor
2,743No known interaction
86 Moderate 2,743 No interaction
Moderate

86 interactions

Showing 60 of 86 moderate interactions — see all 86 on the Tansy Ragwort page.

No interaction 2,743 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 2,743 medications checked with no known interaction — see the full Tansy Ragwort list.

See the full Tansy Ragwort interactions page
See every supplement checked against Ethosuximide, ranked by severity
Sources

Sources & How We Checked

Interaction details are evidence-graded and sourced from the Natural Medicines database. The medication overview comes from MedlinePlus.

Content is written and reviewed by licensed HelloPharmacist pharmacists. See our data sources and editorial standards for how this information is built and checked.

Parts of this content are provided by the Therapeutic Research Center, LLC.

DISCLAIMER: Currently this does not check for drug-drug interactions. This is not an all-inclusive comprehensive list of potential interactions and is for informational purposes only. Not all interactions are known or well-reported in the scientific literature, and new interactions are continually being reported. Input is needed from a qualified healthcare provider including a pharmacist before starting any therapy. Application of clinical judgment is necessary.

© 2021 Therapeutic Research Center, LLC

Keep exploring
Tansy Ragwort monograph › Uses, safety, and every drug interaction in one place Ethosuximide supplement interactions › Every supplement checked against Ethosuximide, ranked by severity Ethosuximide drug information › The full plain-English guide to this medication Supplement interaction checker › Check any supplement or product against your medications Browse medications A–Z › Every drug we've checked against herbs & supplements Ask a pharmacist › Free, personal answer from our licensed team
Pharmacist Counseling Corner

Taking Tansy Ragwort and Ethosuximide Together: Common Questions

Can you take Tansy Ragwort with Ethosuximide?
There is a moderate interaction, so it may be acceptable with monitoring or timing changes — but check with your pharmacist first. Read the full details on this page and confirm with your pharmacist before combining them.
How serious is the Tansy Ragwort and Ethosuximide interaction?
We rate it Moderate. This combination may require monitoring, a dose adjustment, or separating the times you take each one. Consult your pharmacist before using them together.

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

Still Have a Question About Ethosuximide 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.