Drug & supplement interaction

Boldo + 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 Boldo 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

Boldo 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 Boldo 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.

Boldo safety at a glance

Boldo overall Use caution May be used short-term in low doses, but the ascaridole in the leaf and oil can harm the liver.
Pregnancy Possibly Unsafe When used orally in medicinal amounts. In animals, boldo and the constituent boldine have abortive and teratogenic effects. Also, the ascaridole constituent of... Read the full pregnancy detail
Breastfeeding Possibly Unsafe When used orally in medicinal amounts. In animals, boldo and the constituent boldine have abortive and teratogenic effects. Also, the ascaridole constituent of... 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 Boldo? 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. Boldo has documented interactions with 5 drug classes — the most serious being anticoagulant/antiplatelet drugs (moderate), hepatotoxic drugs (moderate) and lithium (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

Boldo Does Interact With Other Medications

Boldo has 482 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 482 No known interaction 2,348 (incl. Ondansetron)
Taking anything else?

Check Another of Your Medications Against Boldo

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

What to actually watch for

No Interaction Found — But Data Suggests Boldo and Ondansetron May Share Several of the Same Side Effects

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.

  • An irregular heartbeat Worth acting on Additional detail

    Boldo

    “In one report, a 39-year-old obese female developed palpitations and syncope after taking a weight loss supplement containing a combination of boldo, dandelion, and bladderwrack for 3 weeks. The patient was found to have prolonged QT-interval on ECG and frequent episodes of sustained polymorphic ventricular tachycardia.”

    Boldo · Natural Medicines adverse-effect record, reported in obesity.

    1 source cited
    1. 14321. Agarwal SC, Crook JR, Pepper CB. Herbal remedies -- how safe are they? A case report of polymorphic ventricular tachycardia/ventricular fibrillation induced by herbal medication used for obesity. Int J Cardiol 2006;106:260-1. PubMed

    Ondansetron

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

  • A fast or pounding heartbeat Additional detail

    Boldo

    Recorded for Boldo in the same Natural Medicines adverse-effect record shown under An irregular heartbeat above.

    Ondansetron

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

Reported for Boldo but not commonly for Ondansetron: stomach upset, liver problems, stomach pain and weight loss.

Effects for Ondansetron come from the ADVERSE REACTIONS section of its FDA label; effects for Boldo 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

Boldo in Pregnancy & Breastfeeding

Pregnancy And Lactation Possibly Unsafe

When used orally in medicinal amounts. In animals, boldo and the constituent boldine have abortive and teratogenic effects. Also, the ascaridole constituent of boldo is a liver toxin.

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 Boldo 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 Boldo 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 Boldo 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

One more smart check

Taking Boldo as Part of a Dietary Supplement Product? Check It for Interactions

We hold 173 real supplement products containing Boldo, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Boldo. Even though Boldo itself has no known interaction with Ondansetron, another ingredient on your label might. Find your product and we’ll check every ingredient on its label:

How much people look this up

Where Boldo 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 Boldo
Top half

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

29 days ago today
Medication Ondansetron
Steady interest

#2,073 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 Boldo reference on this page ↓
  • Freshness: we automatically re-check this combination every week — this pair was last verified September 20, 2026. The Boldo and Ondansetron records this page draws on were last updated July 10, 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 Boldo

What is Boldo?

Boldo
  • Indigestion and bloating
  • Mild constipation
  • Liver and gallbladder support
  • Appetite stimulation
  • Urinary complaints

Boldo is a South American shrub whose leaves are traditionally used for digestive and gallbladder complaints, but good human evidence is very limited. The leaves and oil contain ascaridole, which can be toxic to the liver, so only ascaridole-free products should be used and only for short periods. Talk to your pharmacist or doctor before trying it, and avoid it during pregnancy and breastfeeding.

Peumus boldus · Monimiaceae · Leaves and essential oil · Tea, dried leaf, tincture, capsules, essential oil

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

Boldo: dosing

There is no well-established standardized dose for boldo, and products vary widely in strength and in how much ascaridole they contain. Because of this, it is best to follow the directions on the product label and use it only for short periods.Choose products labeled as ascaridole-free when possible, and avoid the pure essential oil.

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

Read the full Boldo 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 & Boldo

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

0Major
482Moderate
0Minor
2,347No known interaction
482 Moderate 2,347 No interaction
Moderate

482 interactions

Showing 60 of 482 moderate interactions — see all 482 on the Boldo page.

No interaction 2,347 drugs checked — show the list

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

Showing the 60 most looked-up of 2,347 medications checked with no known interaction — see the full Boldo list.

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

Boldo References

The 10 references that drive our Boldo 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. Newall CA, Anderson LA, Philpson JD. Herbal Medicine: A Guide for Healthcare Professionals. London, UK: The Pharmaceutical Press, 1996.
  2. Lambert J, Cormier J. Potential interaction between warfarin and boldo-fenugreek. Pharmacotherapy 2001;21:509-12. PubMed
  3. Piscaglia F, Leoni S, Venturi A, et al. Caution in the use of boldo in herbal laxatives: a case of hepatotoxicity. Scand J Gastroenterol 2005;40:236-9. PubMed
  4. Agarwal SC, Crook JR, Pepper CB. Herbal remedies -- how safe are they? A case report of polymorphic ventricular tachycardia/ventricular fibrillation induced by herbal medication used for obesity. Int J Cardiol 2006;106:260-1. PubMed
  5. Teng, C. M., Hsueh, C. M., Chang, Y. L., Ko, F. N., Lee, S. S., and Liu, K. C. Antiplatelet effects of some aporphine and phenanthrene alkaloids in rabbits and man. J Pharm Pharmacol 1997;49(7):706-711. PubMed
  6. Carbajal R, Yisfalem A, Pradhan N, et al. Case report: Boldo (Peumus boldus) and tacrolimus interaction in a renal transplant patient. Transplant Proc 2014;46(7):2400-2. PubMed
  7. Almeida ER, Melo AM, Xavier H. Toxicological evaluation of the hydro-alcohol extract of the dry leaves of Peumus boldus and boldine in rats. Phytother Res 2000;14(2):99-102. DOI
  8. Ribeiro RJ, Silvestre C, Duarte C. Hidden risks of alternative medicines: a case of boldo-induced hepatotoxicity. J Diet Suppl 2017;14(2):186-90. PubMed
  9. Oliveira Sá A, Pimentel T, Oliveira N. Boldo-Induced Hepatotoxicity: A Case of Unexplained Jaundice. Eur J Case Rep Intern Med 2020;7(12):002116. PubMed
  10. Valdes R, Feuereisen A, Bellinghausen M. Allergic Contact Dermatitis to Boldo. Dermatitis 2021;32(2):e31-e32. 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 Boldo and Ondansetron Together: Common Questions

Is it safe to take Boldo with Ondansetron?
We do not list a known interaction between Boldo 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 Boldo and Ondansetron have any of the same side effects?
Yes — our sources link each of them separately to 2 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 Boldo and Ondansetron combination checked?
Interactions in our licensed database are recorded against drug classes. Ondansetron is filed under 7 classifications, and Boldo has documented interactions with 5 drug classes — 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 Boldo interact with any other medications?
Yes. Boldo has 482 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 — Boldo 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

Boldo 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 10 citations behind this page Ask a pharmacist Free, personal answer from our licensed team

Still Have a Question About Ondansetron and Boldo?

Our pharmacists answer your medication & supplement questions — free.

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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.