Drug & supplement interaction

Pennyroyal + Amoxicillin

Amoxicillin brand names: Amoxil Capsules, Trimox, Wymox, Amix, Amoram, and others.

No Known Interaction
Medically reviewed by · Updated July 2026 · Pair last verified Sep 13, 2026
The bottom line No known interaction

We found no known interaction between Pennyroyal and Amoxicillin 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.

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Interaction report

Pennyroyal and Amoxicillin

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 Amoxicillin and Pennyroyal 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.

Pennyroyal safety at a glance

Pennyroyal overall Avoid Pennyroyal oil is highly toxic and has caused liver failure and death.
Pregnancy Likely Unsafe When used orally or topically. Pennyroyal essential oil has been used traditionally as an abortifacient. Pennyroyal leaf tea is reported to cause onset of mense... Read the full pregnancy detail
Breastfeeding Likely Unsafe When used orally or topically; avoid using. 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 Amoxicillin and Pennyroyal? Ask Dr. Brian Staiger, PharmD, BCPS directly ›
How we checked

Why No Interaction Is Listed for Amoxicillin

Interactions in our licensed database are recorded against drug classes, not just single drug names. Amoxicillin is filed under 7 classifications — including penicillin, antibiotic drugs, nephrotoxic drugs. Pennyroyal has documented interactions with 1 drug class — the most serious being acetaminophen (tylenol, others) (moderate) — and none of Amoxicillin’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

Pennyroyal Does Interact With Other Medications

Pennyroyal has 69 moderate known drug interactions in our database — Amoxicillin isn’t one of them. If you take anything else, check it against the full list below.

Moderate 69 No known interaction 2,761 (incl. Amoxicillin)
Taking anything else?

Check Another of Your Medications Against Pennyroyal

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

What to actually watch for

What Pennyroyal Itself Has Been Linked To

This is not an interaction — nothing below involves Amoxicillin. It is the side-effect record for Pennyroyal on its own, from the licensed Natural Medicines monograph. If something new turns up after you add Pennyroyal, this list is the first place to look. 5 entries are worth acting on rather than waiting out — marked below.

  • Hallucinations / Confusion Worth acting on Additional detail

    “Orally, pennyroyal essential oil can cause agitation, auditory and visual hallucinations, confusion, delirium, and lethargy (12,5601).”

    Pennyroyal · Natural Medicines adverse-effect record, reported in delirium.

    2 sources cited
    1. 12. McGuffin M, Hobbs C, Upton R, Goldberg A, eds. American Herbal Products Association's Botanical Safety Handbook. Boca Raton, FL: CRC Press, LLC 1997.
    2. 5601. Sullivan JB Jr, Rumack BH, Thomas H Jr, et al. Pennyroyal oil poisoning and hepatotoxicity. JAMA 1979;242:2873-4. DOI
  • An irregular heartbeat Worth acting on Additional detail

    “The main constituent of pennyroyal essential oil, pulegone, and its metabolite menthofuran, are hepatotoxic (12). Orally, pennyroyal essential oil can cause liver failure (12,5601). A case report describes a 76-year-old adult who developed liver failure with duodenitis, hypotension, and cardiac arrhythmias after taking pennyroyal and acetaminophen concurrently.”

    Pennyroyal · Natural Medicines adverse-effect record, reported in arrhythmia.

    3 sources cited
    1. 12. McGuffin M, Hobbs C, Upton R, Goldberg A, eds. American Herbal Products Association's Botanical Safety Handbook. Boca Raton, FL: CRC Press, LLC 1997.
    2. 5601. Sullivan JB Jr, Rumack BH, Thomas H Jr, et al. Pennyroyal oil poisoning and hepatotoxicity. JAMA 1979;242:2873-4. DOI
    3. 101477. Fozard J, Hieger M. Hepatic failure from pennyroyal tea interaction with medications metabolized by the cytochrome P450 enzymes. Am J Ther 2019 Aug 13. doi: 10.1097/MJT.0000000000001052. [Epub ahead of print]. PubMed
  • Seizures Worth acting on Additional detail

    “Orally, herbal teas prepared with pennyroyal leaves can cause dizziness (12). Orally, pennyroyal essential oil can cause coma, dizziness, restlessness, and seizures (12,5601).”

    Pennyroyal · Natural Medicines adverse-effect record, reported in epilepsy.

    2 sources cited
    1. 12. McGuffin M, Hobbs C, Upton R, Goldberg A, eds. American Herbal Products Association's Botanical Safety Handbook. Boca Raton, FL: CRC Press, LLC 1997.
    2. 5601. Sullivan JB Jr, Rumack BH, Thomas H Jr, et al. Pennyroyal oil poisoning and hepatotoxicity. JAMA 1979;242:2873-4. DOI
  • Kidney problems Worth acting on Additional detail

    “Orally, pennyroyal essential oil can cause kidney failure (12,5601).”

    Pennyroyal · Natural Medicines adverse-effect record, reported in kidney failure.

    2 sources cited
    1. 12. McGuffin M, Hobbs C, Upton R, Goldberg A, eds. American Herbal Products Association's Botanical Safety Handbook. Boca Raton, FL: CRC Press, LLC 1997.
    2. 5601. Sullivan JB Jr, Rumack BH, Thomas H Jr, et al. Pennyroyal oil poisoning and hepatotoxicity. JAMA 1979;242:2873-4. DOI
  • Raised blood pressure Worth acting on Additional detail

    “Orally, pennyroyal essential oil can cause hypertension, shock, and tachycardia (12,5601).”

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

    2 sources cited
    1. 12. McGuffin M, Hobbs C, Upton R, Goldberg A, eds. American Herbal Products Association's Botanical Safety Handbook. Boca Raton, FL: CRC Press, LLC 1997.
    2. 5601. Sullivan JB Jr, Rumack BH, Thomas H Jr, et al. Pennyroyal oil poisoning and hepatotoxicity. JAMA 1979;242:2873-4. DOI
  • A fast or pounding heartbeat Additional detail

    Recorded for Pennyroyal in the same Natural Medicines adverse-effect record shown under Raised blood pressure above.

  • Low blood pressure Additional detail

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

  • Anxiety or restlessness Additional detail

    Recorded for Pennyroyal in the same Natural Medicines adverse-effect record shown under Hallucinations / Confusion above.

  • Stomach pain Additional detail

    “Orally, herbal teas prepared with pennyroyal leaves can cause nausea and abdominal cramping (12). Pennyroyal essential oil causes more severe gastrointestinal effects, including abdominal pain, burning of the throat, and vomiting (12,5601).”

    Pennyroyal · Natural Medicines adverse-effect record, reported in nausea and vomiting.

    2 sources cited
    1. 12. McGuffin M, Hobbs C, Upton R, Goldberg A, eds. American Herbal Products Association's Botanical Safety Handbook. Boca Raton, FL: CRC Press, LLC 1997.
    2. 5601. Sullivan JB Jr, Rumack BH, Thomas H Jr, et al. Pennyroyal oil poisoning and hepatotoxicity. JAMA 1979;242:2873-4. DOI

Showing the 10 most notable of 15 recorded effects — ranked by how unusual each one is across medicines generally, with serious effects weighted up.

Everything above comes from the Natural Medicines adverse-effect record for Pennyroyal — expand a row for the licensed statement it rests on. We haven’t matched Amoxicillin to its FDA label in our system yet, so we can’t compare its own side-effect list here — the leaflet that comes with your prescription is the authoritative list for Amoxicillin.

Special populations

Pennyroyal in Pregnancy & Breastfeeding

Pregnancy Likely Unsafe

When used orally or topically. Pennyroyal essential oil has been used traditionally as an abortifacient. Pennyroyal leaf tea is reported to cause onset of menses.

Lactation Likely Unsafe

When used orally or topically; avoid using.

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

Overlapping uses

What Amoxicillin Is Prescribed For, and What Pennyroyal Has Been Studied For

These two come up together because they touch the same health topic — not because they do the same job. Amoxicillin is a prescription medicine with approved uses on its FDA label. Pennyroyal is a supplement: what follows is what researchers have looked at it for, and how strong that evidence is.

Amoxicillin is prescribed for: Amoxicillin treats bacterial infections in both adults and children, including ear, nose, and throat infections; lower respiratory tract infections; skin and skin structure infections; and genitourinary tract infections. In adults only, amoxicillin is also used — always combined with other medications — to eradicate Helicobacter pylori (H. pylori), the bacteria behind duodenal ulcers. Getting rid of H.

Read the rest of what Amoxicillin is prescribed for

pylori has been shown to reduce the chance of those ulcers coming back. It is only effective against bacteria that are susceptible to it and will not work against viral infections like the common cold or flu.

Pennyroyal has been studied for:

  • Common cold studied, not established Pennyroyal has been studied for this. Natural Medicines rates the evidence: Insufficient Reliable Evidence To Rate Read what the research shows

    Pennyroyal for common cold

    Although there has been interest in using oral pennyroyal for treating colds, there is insufficient reliable information about the clinical effects of pennyroyal for this purpose.

  • Pneumonia studied, not established Pennyroyal has been studied for this. Natural Medicines rates the evidence: Insufficient Reliable Evidence To Rate Read what the research shows

    Pennyroyal for pneumonia

    Although there has been interest in using oral pennyroyal for treating pneumonia, there is insufficient reliable information about the clinical effects of pennyroyal for this purpose.

Effectiveness ratings and the research summaries above are the verbatim record from the Natural Medicines database, which grades evidence from “Effective” down to “Insufficient Reliable Evidence To Rate”. A rating below the top of that scale means researchers have looked at it — not that it works, and never that it can stand in for a prescribed medicine. Do not stop or replace Amoxicillin on your own; if you are taking Pennyroyal for the same health topic, tell your prescriber, especially if the medicine is being adjusted to a target.

From our Q&A

Questions About Pennyroyal or Amoxicillin

These are real questions from readers, answered by the pharmacists at HelloPharmacist — written by a person, not generated from a database. Each one covers Pennyroyal or Amoxicillin, 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 Amoxicillin

This page covers Pennyroyal only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Amoxicillin page lists 96 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), Asarabacca (major), Beer (major), Khat (major) and Siberian Cocklebur (major).

By severity: 6 major · 76 moderate · 14 minor.

From our pharmacist’s overview on the Amoxicillin page

“Amoxicillin, one of the most commonly prescribed antibiotics, has 96 supplement and herbal ingredients flagged against it, and six carry a major rating, which puts this list in the read-carefully category. The serious entries mostly add strain to organs the drug already touches.”

Reviewed by 2 · Jul 18, 2026

Open the Amoxicillin interaction page

One more smart check

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

We hold 11 real supplement products containing Pennyroyal, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Pennyroyal. Even though Pennyroyal itself has no known interaction with Amoxicillin, 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 Pennyroyal and Amoxicillin 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 Pennyroyal
Steady interest

#1,120 of 1,452 supplements looked up here in the last 7 days

29 days ago today
Medication Amoxicillin
Top 5%

#36 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 Pennyroyal reference on this page ↓
  • Freshness: we automatically re-check this combination every week — this pair was last verified September 13, 2026. The Pennyroyal and Amoxicillin 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 Pennyroyal

What is Pennyroyal?

  • Digestive upset
  • Menstrual cramps
  • Inducing menstruation or abortion (dangerous)
  • Colds and coughs
  • Insect repellent

Pennyroyal is a mint-family plant whose essential oil is highly toxic and has caused serious poisonings and deaths, especially when used to try to bring on a period or end a pregnancy. There is no reliable evidence that it safely treats any condition, and the oil should never be swallowed. Avoid pennyroyal and talk to your pharmacist or doctor about safer options.

Mentha pulegium · Lamiaceae · Leaves, flowering tops, and essential oil · Tea, dried herb, tincture, essential oil

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

Pennyroyal: dosing

There is no established safe dose for pennyroyal, and health experts generally advise against using it at all because of its toxicity.The essential oil should never be swallowed, and even teas made from the herb carry risk. Because of these dangers, we do not recommend a dose.

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

Read the full Pennyroyal monograph & all interactions
Medication

About Amoxicillin

What Is Amoxicillin Used For?

Brand names: Amoxil Capsules, Trimox, Wymox, Amix, Amoram, Amoxident, Galenamox, Rimoxallin, Amoxil Injection

Amoxicillin treats bacterial infections in both adults and children, including ear, nose, and throat infections; lower respiratory tract infections; skin and skin structure infections; and genitourinary tract infections.

In adults only, amoxicillin is also used — always combined with other medications — to eradicate Helicobacter pylori (H. pylori), the bacteria behind duodenal ulcers. Getting rid of H. pylori has been shown to reduce the chance of those ulcers coming back. It is only effective against bacteria that are susceptible to it and will not work against viral infections like the common cold or flu.

Most-Reported Side Effects for Amoxicillin

From FAERS, the FDA’s public side-effect reporting system (0 reports, all brands). Reports are voluntary and are not proof the drug caused the effect.

Diarrhea 6,010 reports
Drug hypersensitivity 5,482 reports
Nausea 5,158 reports
Dyspnea 5,001 reports
Acute kidney injury 4,989 reports
See full Amoxicillin drug information
Keep checking

Other Drugs & Pennyroyal

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

0Major
69Moderate
0Minor
2,760No known interaction
69 Moderate 2,760 No interaction
Moderate

69 interactions

Showing 60 of 69 moderate interactions — see all 69 on the Pennyroyal page.

No interaction 2,760 drugs checked — show the list

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

Showing the 60 most looked-up of 2,760 medications checked with no known interaction — see the full Pennyroyal list.

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

Pennyroyal References

The 8 references that drive our Pennyroyal 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. The Review of Natural Products by Facts and Comparisons. St. Louis, MO: Wolters Kluwer Co., 1999.
  3. McGuffin M, Hobbs C, Upton R, Goldberg A, eds. American Herbal Products Association's Botanical Safety Handbook. Boca Raton, FL: CRC Press, LLC 1997.
  4. Bakerink JA, Gospe SM Jr, Dimand RJ, Eldridge MW. Multiple organ failure after ingestion of pennyroyal oil from herbal tea in two infants. Pediatrics 1996;98:944-7. DOI
  5. Sudekum M, Poppenga RH, Raju N, Braselton WE Jr. Pennyroyal oil toxicosis in a dog. J Am Vet Med Assoc 1992;200:817-8.. DOI
  6. Anderson IB, Mullen WH, Meeker JE, et al. Pennyroyal toxicity: measurement of toxic metabolite levels in two cases and review of the literature. Ann Intern Med 1996;124:726-34. PubMed
  7. Sullivan JB Jr, Rumack BH, Thomas H Jr, et al. Pennyroyal oil poisoning and hepatotoxicity. JAMA 1979;242:2873-4. DOI
  8. Fozard J, Hieger M. Hepatic failure from pennyroyal tea interaction with medications metabolized by the cytochrome P450 enzymes. Am J Ther 2019 Aug 13. doi: 10.1097/MJT.0000000000001052. [Epub ahead of print]. 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 Pennyroyal and Amoxicillin Together: Common Questions

Is it safe to take Pennyroyal with Amoxicillin?
We do not list a known interaction between Pennyroyal and Amoxicillin. 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.
Are Pennyroyal and Amoxicillin used for the same thing?
They overlap in purpose, which usually means the real question is whether you need both rather than whether they are safe together. This page lists the shared uses and how strong the evidence is for Pennyroyal in each. That is a conversation for your prescriber, especially if Amoxicillin is being adjusted to a target.
How was the Pennyroyal and Amoxicillin combination checked?
Interactions in our licensed database are recorded against drug classes. Amoxicillin is filed under 7 classifications, and Pennyroyal has documented interactions with 1 drug class — none of Amoxicillin'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 Pennyroyal interact with any other medications?
Yes. Pennyroyal has 69 documented drug interactions in our database — Amoxicillin 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 Amoxicillin interact with any supplements?
Yes. Amoxicillin has documented interactions with 96 supplements in our database — Pennyroyal is not one of them. The Amoxicillin 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

Pennyroyal monograph Uses, safety profile, and every drug interaction in one place Amoxicillin drug information The full plain-English guide to this medication Amoxicillin supplement interactions Every supplement checked against Amoxicillin, 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 8 citations behind this page Ask a pharmacist Free, personal answer from our licensed team

Still Have a Question About Amoxicillin and Pennyroyal?

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.