Drug & supplement interaction

Shepherd's Purse + Quinidine

Quinidine brand names: Quinaglute Duratabs, Quinaglute, Duraquin, Cardioquin, Cin-Quin, and others.

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 Shepherd's Purse and Quinidine 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

Shepherd's Purse and Quinidine

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 Quinidine and Shepherd's Purse 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.

Shepherd's Purse safety at a glance

Shepherd's Purse overall Use caution May be used short-term by some adults, but human safety data are limited.
Pregnancy Likely Unsafe When used orally or topically, due to possible uterine stimulation, menstrual flow stimulation, and miscarriage. Read the full pregnancy detail
Breastfeeding Avoid Not enough safety information, so avoid while breastfeeding.

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 Quinidine and Shepherd's Purse? Ask Dr. Brian Staiger, PharmD, BCPS directly ›
How we checked

Why No Interaction Is Listed for Quinidine

Interactions in our licensed database are recorded against drug classes, not just single drug names. Quinidine is filed under 9 classifications — including cytochrome p450 2d6 (cyp2d6) inhibitors, qt interval-prolonging drugs, p-glycoprotein substrates. Shepherd's Purse has documented interactions with 2 drug classes — the most serious being cns depressants (moderate) and thyroid hormone (moderate) — and none of Quinidine’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

Shepherd's Purse Does Interact With Other Medications

Shepherd's Purse has 264 moderate known drug interactions in our database — Quinidine isn’t one of them. If you take anything else, check it against the full list below.

Moderate 264 No known interaction 2,566 (incl. Quinidine)
Taking anything else?

Check Another of Your Medications Against Shepherd's Purse

Covers the 2,830 medications we’ve checked against Shepherd's Purse. Pick one to open its full report.

What to actually watch for

No Interaction Found — But Data Suggests Shepherd's Purse and Quinidine 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.

  • Low blood pressure Additional detail

    Shepherd's Purse

    “Orally, shepherd's purse seems to be well tolerated when used in small amounts, short-term. Adverse effects traditionally thought to be associated with shepherd's purse have included sedation, hypertension, hypotension, abnormal thyroid function, abnormal menstruation (4), and palpitations (12).”

    Shepherd's Purse · Natural Medicines adverse-effect record, reported in hypertension.

    2 sources cited
    1. 4. Newall CA, Anderson LA, Philpson JD. Herbal Medicine: A Guide for Healthcare Professionals. London, UK: The Pharmaceutical Press, 1996.
    2. 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.

    “Orally, some adverse effects traditionally thought to be associated with shepherd's purse have included hypertension, hypotension, (4), and palpitations (12).”

    Shepherd's Purse · Natural Medicines adverse-effect record, reported in hypertension.

    2 sources cited
    1. 4. Newall CA, Anderson LA, Philpson JD. Herbal Medicine: A Guide for Healthcare Professionals. London, UK: The Pharmaceutical Press, 1996.
    2. 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.

    Quinidine

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

Reported for Shepherd's Purse but not commonly for Quinidine: a change in thyroid levels, a fast or pounding heartbeat, raised blood pressure and drowsiness.

Effects for Quinidine come from the ADVERSE REACTIONS section of its FDA label; effects for Shepherd's Purse come from the Natural Medicines adverse-effect record, quoted above. Wording is matched across sources by our own clinical vocabulary, so treat this as a prompt to pay attention, not a diagnosis.

Special populations

Shepherd's Purse in Pregnancy & Breastfeeding

Pregnancy Likely Unsafe

When used orally or topically, due to possible uterine stimulation, menstrual flow stimulation, and miscarriage.

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 Shepherd's Purse or Quinidine

These are real questions from readers, answered by the pharmacists at HelloPharmacist — written by a person, not generated from a database. Each one covers Shepherd's Purse or Quinidine, 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 Quinidine

This page covers Shepherd's Purse only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Quinidine page lists 207 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), American Hellebore (major), Arsenic (major), Beer (major) and Cesium (major).

By severity: 15 major · 157 moderate · 35 minor.

From our pharmacist’s overview on the Quinidine page

“Grapefruit belongs nowhere near quinidine. The juice blocks the main enzyme that clears this heart rhythm medicine, so quinidine levels can climb into dangerous territory, and it leads a list of 207 supplement and herbal ingredients I would treat with real seriousness, 15 of them rated major.”

Reviewed by 2 · Jul 18, 2026

Open the Quinidine interaction page

One more smart check

Taking Shepherd's Purse as Part of a Dietary Supplement Product? Check It for Interactions

We hold 73 real supplement products containing Shepherd's Purse, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Shepherd's Purse. Even though Shepherd's Purse itself has no known interaction with Quinidine, 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 Shepherd's Purse and Quinidine 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 Shepherd's Purse
Steady interest

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

29 days ago today
Medication Quinidine
Top half

#1,338 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 Shepherd's Purse reference on this page ↓
  • Freshness: we automatically re-check this combination every week — this pair was last verified September 20, 2026. The Shepherd's Purse and Quinidine 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 Shepherd's Purse

What is Shepherd's Purse?

Shepherd's Purse
  • Heavy or prolonged menstrual bleeding
  • Minor bleeding (nosebleeds, wounds)
  • Mild diuretic
  • Digestive complaints
  • After-childbirth bleeding (traditional)

Shepherd's purse is a traditional herb most often used to help slow heavy menstrual bleeding and other minor bleeding, but solid human research is very limited. Because it may affect blood clotting, blood pressure, and the uterus, it should be avoided during pregnancy and used cautiously under professional guidance.

Capsella bursa-pastoris · Brassicaceae · Above-ground parts (leaves, stems, flowers, and seed pods) · Tea, liquid extract/tincture, dried herb, capsules

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

Shepherd's Purse: dosing

There is no official, standardized dose for shepherd's purse. The right amount can vary by product, form (tea, tincture, or capsule), and how concentrated it is.The safest approach is to follow the directions on the product label and not exceed them.

From our Shepherd's Purse monograph — the full record covers uses, side effects and every documented interaction.

Read the full Shepherd's Purse monograph & all interactions
Medication

About Quinidine

What Is Quinidine Used For?

Brand names: Quinaglute Duratabs, Quinaglute, Duraquin, Cardioquin, Cin-Quin, Quinora, Lin-Qin, Quinova, Quinidex Extentabs

Quinidine is used to help restore a normal heart rhythm in people with atrial fibrillation or atrial flutter (irregular, rapid heart rhythms originating in the upper chambers). It is also used on an ongoing basis to reduce how often those episodes come back, in patients whose episodes are frequent and poorly tolerated — but only after other options have been tried first.

Quinidine sulfate oral tablets and quinidine gluconate extended-release oral tablets are both approved for these heart-rhythm uses. Quinidine sulfate tablets are additionally used as part of an approved treatment regimen for life-threatening Plasmodium falciparum malaria, in combination with quinidine gluconate injection (the central component of that regimen). Both formulations may also be used to suppress recurrent, documented life-threatening ventricular arrhythmias (dangerous rapid rhythms in the lower chambers of the heart), such as sustained ventricular tachycardia.

See full Quinidine drug information
Keep checking

Other Drugs & Shepherd's Purse

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

0Major
264Moderate
0Minor
2,565No known interaction
264 Moderate 2,565 No interaction
Moderate

264 interactions

Showing 60 of 264 moderate interactions — see all 264 on the Shepherd's Purse page.

No interaction 2,565 drugs checked — show the list

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

Showing the 60 most looked-up of 2,565 medications checked with no known interaction — see the full Shepherd's Purse list.

See the full Shepherd's Purse interactions page
See every supplement checked against Quinidine, ranked by severity
Evidence & sources

Shepherd's Purse References

The 4 references that drive our Shepherd's Purse 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. McGuffin M, Hobbs C, Upton R, Goldberg A, eds. American Herbal Products Association's Botanical Safety Handbook. Boca Raton, FL: CRC Press, LLC 1997.
  3. Naafe M, Kariman N, Keshavarz Z, et al. Effect of hydroalcoholic extracts of Capsella bursa-pastoris on heavy menstrual bleeding: A randomized clinical trial. J Altern Complement Med. 2018;24(7):694-700. PubMed
  4. Ghalandari S, Kariman N, Sheikhan Z, et al. Effect of hydroalcoholic extract of Capsella bursa pastoris on early postpartum hemorrhage: A clinical trial study. J Altern Complement Med. 2017;23(10):794-799.

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 Shepherd's Purse and Quinidine Together: Common Questions

Is it safe to take Shepherd's Purse with Quinidine?
We do not list a known interaction between Shepherd's Purse and Quinidine. 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 Shepherd's Purse and Quinidine 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 Shepherd's Purse and Quinidine combination checked?
Interactions in our licensed database are recorded against drug classes. Quinidine is filed under 9 classifications, and Shepherd's Purse has documented interactions with 2 drug classes — none of Quinidine'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 Shepherd's Purse interact with any other medications?
Yes. Shepherd's Purse has 264 documented drug interactions in our database — Quinidine 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 Quinidine interact with any supplements?
Yes. Quinidine has documented interactions with 207 supplements in our database — Shepherd's Purse is not one of them. The Quinidine 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

Shepherd's Purse monograph Uses, safety profile, and every drug interaction in one place Quinidine drug information The full plain-English guide to this medication Quinidine supplement interactions Every supplement checked against Quinidine, 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 Quinidine and Shepherd's Purse?

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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.