Herb & supplement monograph

Shepherd's Purse Drug Interactions, Uses, Effectiveness, Safety & More

Medically reviewed by ·Updated July 2026
What is this page for?

First and foremost: how Shepherd's Purse interacts with medications. The heart of this page is the interaction list — every drug Shepherd's Purse is known to interact with, and how serious each one is.

But these pages have grown well beyond that into a full monograph — what Shepherd's Purse is, what people use it for and how strong the evidence is, its safety and side effects, and answers to the questions we’re asked most — written and reviewed by the clinical staff at HelloPharmacist. It’s educational information from our licensed clinical databases, not medical advice, and we don’t sell or endorse products. Our editorial policy

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Shepherd's Purse Drug Interactions: The Bottom Line

From the HelloPharmacist Editorial Team · Updated July 2026

Based on the available evidence, the overall risk of a clinically significant Shepherd's Purse drug interaction appears low for most people. None of the listed interactions are rated major, and all of them rest on theoretical concerns rather than documented reactions in people.

Interactions deserving the most attention

Two groups of medicines deserve the most attention. Shepherd's Purse may have mild sedative effects, so combining it with sedating medications, such as sleep aids, anxiety medicines, or opioid pain relievers, could in theory add to drowsiness. It may also interfere with thyroid hormone treatment, which matters because thyroid medicines are dosed carefully and even small changes in effect can show up in lab results. Neither concern has been confirmed in human studies, but these are the combinations we would watch most closely.

What the rest of the list means

Although the number of medications on the list looks large, it comes almost entirely from these two broad drug groups. The interactions are theoretical, based on how Shepherd's Purse might act in the body rather than on problems actually reported in people. A long list, in this case, reflects caution rather than proven harm.

Check your medications against Shepherd's Purse

Based on HelloPharmacist’s Shepherd's Purse interaction data and reviewed under our editorial standards.

Interaction report

Drugs that interact with Shepherd's Purse

264 medications have a known interaction with Shepherd's Purse, graded by severity. Select any drug for the full evidence-based detail.

2,830 drugs
AcepromazineAtravet› Acetaminophen, Butalbital, Caffeine, CodeineEsgic with Codeine, Fioricet w/ Codeine› Acetaminophen, Butalbital, CodeineBancap w/ Codeine› Acetaminophen, Butalbital, Codeine PhosphatePhrenilin #3› Acetaminophen, Caffeine, Chlorpheniramine, Hydrocodone, PhenylephrineHycomine Compound› Acetaminophen, Caffeine, CodeineGesic C15, Gesic C30, Gesic C8, Lenoltec 1, Lenoltec 2, Lenoltec 3 +1 more› Acetaminophen, Caffeine, Codeine, SalicylamideCodalan No.1, Codalan No.2, Codalan No.3› Acetaminophen, Caffeine, DihydrocodeineDHC Plus, Panlor DC, Panlor SS› Acetaminophen, Chlorpheniramine, Codeine, PhenylephrineColrex› Acetaminophen, Chlorpheniramine, Phenylpropanolamine, OpiumHista-Derfule› Acetaminophen, Chlorzoxazone, CodeineAcetazone Forte C8, Parafon Forte C8› Acetaminophen, CodeineTylenol No.3, Tylenol w/ Codeine› Acetaminophen, Codeine, DoxylamineMersyndol› Acetaminophen, Codeine, MethocarbamolAcetaminophen, Codeine, Methocarbamol, Robaxacet 8› Acetaminophen, Dichloralantipyrine, IsomethepteneAmidrine, Midchlor, Migquin, Migratine› Acetaminophen, Dichloralphenazone, IsomethepteneMidrin› Acetaminophen, Dichlorophenazone, IsometheptaneIsocom› Acetaminophen, DiphenhydramineTylenol PM, Tylenol PM Ex Strength› Acetaminophen, Diphenhydramine, PseudoephedrineChildren's Tylenol Allergy, Cold Control, Contac Night Allergy Relief› Acetaminophen, HydrocodoneAnexsia, Anodynos DHC, Azdone, Co-Gesic, Doucet, Lorcet +9 more› Acetaminophen, MeperidineDemerol APAP› Acetaminophen, OxycodonePercocet, Roxicet, Tylox, Xartemis XR› Acetaminophen, PentazocineTalacen› Acetaminophen, PropoxypheneDarvocet-N 100, Darvocet-N 50, E-Lor, Wygesic› AcetazolamideAk-Zol, Diamox› AlfentanilAlfenta› AlprazolamNiravam, Xanax› Aluminum Hydroxide, Aspirin, Codeine Phosphate, Magnesium HydroxideAscriptin Codeine #2› AminoglutethimideCytadren› Aminophylline, Amobarbital, EphedrineAmesec›
Read The List Like a Pharmacist

What Severity, Likelihood & Evidence Mean

Severity — How Serious It Can Be

  • Major. Clinically significant; generally best avoided, or used only under direct professional supervision.
  • Moderate. May need monitoring, a dose adjustment, or separating the times you take each one.
  • Minor. Generally not clinically significant, but still worth noting and mentioning to your pharmacist.
  • No known interaction. Checked against our sources with nothing documented — not the same as proven safety.

Likelihood — How Well It’s Documented

  • Likely. Well-controlled human studies have demonstrated the likely existence of this interaction
  • Probable. Interaction 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.
  • Possible. 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
  • Unlikely. Interaction has been demonstrated in animal or in lab research but has been shown not to occur in humans.

Where This Data Comes From

  • Interaction records are evidence-graded and sourced from the Natural Medicines database (TRC Healthcare), the same reference used by pharmacists and hospitals.
  • Each drug listed above links to the full report for that exact Shepherd's Purse combination — clinical detail, likelihood, evidence level, and citations.
  • Content is reviewed by licensed HelloPharmacist pharmacists — see our data sources and editorial standards.
The big picture

The kinds of drugs Shepherd's Purse affects

Every type of medication (drug category) Shepherd's Purse is known to interact with. Open any category for the detail — or search your exact drug in the checker above.

All 2 drug categories Shepherd's Purse interacts with
Cns DepressantsThyroid Hormone
Cns Depressants

Theoretically, concomitant use with drugs with sedative properties may cause additive effects and side effects.

Likelihood Possible Evidence D
Thyroid Hormone

Theoretically, concomitant use may interfere with thyroid dysfunction therapy.

Likelihood Possible Evidence D
Monograph

Shepherd's Purse: Uses, Safety & Side Effects

Medically reviewed by · Reviewed July 2026 ·
The bottom line

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.

Shepherd's Purse
Scientific name
Capsella bursa-pastoris
Family
Brassicaceae
Part used
Above-ground parts (leaves, stems, flowers, and seed pods)
Common forms
Tea, liquid extract/tincture, dried herb, capsules
People commonly use it for
  • Heavy or prolonged menstrual bleeding
  • Minor bleeding (nosebleeds, wounds)
  • Mild diuretic
  • Digestive complaints
  • After-childbirth bleeding (traditional)

Popular and traditional uses — not proof it works. See “Uses & effectiveness” below for the evidence.

Safety at a glance
OverallUse caution

May be used short-term by some adults, but human safety data are limited.

PregnancyLikely Unsafe

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

Read the full pregnancy detail
BreastfeedingInsufficient reliable information

Insufficient reliable information available; avoid excessive use.

Read the full breastfeeding detail

Pregnancy & breastfeeding ratings are from Natural Medicines (Therapeutic Research Center). Safety guidance is general; always confirm with your pharmacist or doctor for your situation.

Jump to a section

Overview

Shepherd's purse (Capsella bursa-pastoris) is a small flowering plant in the mustard family. It is named for its tiny, triangular seed pods that look like the leather pouches once carried by shepherds.

The plant is native to Europe and Asia and now grows as a common weed in many parts of the world. The leaves, stems, and flowering tops have a long history of use in traditional and folk medicine.

People most often take shepherd's purse as a tea or liquid extract. It is best known as a folk remedy for heavy menstrual bleeding and other types of minor bleeding.

How it works

Shepherd's purse contains plant compounds such as flavonoids, organic acids, and other substances that may have astringent (tissue-tightening) effects. These effects are thought to be behind its traditional use for bleeding.

Laboratory and animal studies suggest it may affect blood vessels, blood clotting, and smooth muscle, including the muscle of the uterus. This could explain its traditional use for menstrual and after-birth bleeding.

It is important to know that these proposed mechanisms come mostly from test-tube and animal research. How well they apply to people taking the herb is not well established.

Effectiveness

Does Shepherd's Purse work?

Here’s what the research actually shows for each use — graded by Natural Medicines and reviewed by .

Evidence overview · 2 uses evaluated
2 Insufficient evidence
How to read these evidence grades

Natural Medicines’ 7-point scale. We show each rating’s label word-for-word.

1EffectiveStrong, consistent evidence it works.
2Likely EffectiveGood evidence, though not yet conclusive.
3Possibly EffectiveSome evidence suggests a benefit.
4Possibly IneffectiveSome evidence it may not help.
5Likely IneffectiveFairly strong evidence it doesn’t help.
6IneffectiveStrong evidence it doesn’t work.
7Insufficient Reliable Evidence to RateToo little research to say either way.

For Shepherd's Purse, current evidence isn’t strong enough to rate any specific use. The conditions it has been studied for are listed below.

Also studied for 2 conditions — evidence insufficient to rate
Insufficient Reliable Evidence To Rate Menorrhagia
Rating & evidence shown verbatim from Natural Medicines

Clinical research shows that taking shepherd's purse extract 640 mg twice daily with mefenamic acid 1000 mg three times daily up to 7 days during menstruation for two consecutive cycles decreases menstrual bleeding by 50% in the third cycle compared with a 45% reduction in women with heavy menstrual bleeding taking mefenamic acid only. The clinical significance of this small benefit is unclear.

Sources Ref 102404
Insufficient Reliable Evidence To Rate Postpartum complications
Rating & evidence shown verbatim from Natural Medicines

Preliminary clinical research in postpartum women shows that taking shepherd's purse extract as ten sublingual drops, with an infusion of oxytocin, reduces postpartum bleeding by 32% in the first 3 hours after birth compared with oxytocin alone.

Sources Ref 102405

Source & disclaimer. Effectiveness ratings and evidence summaries are provided by Natural Medicines (Therapeutic Research Center) and shown as licensed. Where Natural Medicines hasn’t rated a use, HelloPharmacist’s pharmacists may add their own reviewed rating and evidence (each such entry is labeled). This is educational information, not medical advice — talk with your pharmacist or doctor before starting, stopping, or changing a supplement.

Safety & precautions

There is limited modern safety data on shepherd's purse. When used short-term in usual amounts, it appears to be reasonably well tolerated by many adults, but this is not guaranteed.

Pregnancy: Avoid it. Because the herb may stimulate the uterus and affect bleeding, it could be risky during pregnancy.

Breastfeeding: Avoid it. There is not enough information to consider it safe while nursing.

People with bleeding disorders, heart conditions, low or high blood pressure, thyroid problems, kidney stones, or those scheduled for surgery should be cautious and talk with a doctor first. Because it may affect clotting and blood pressure, stop using it before any planned surgery. Always check with a pharmacist or doctor before starting it.

Side effects

Reported side effects are not well documented, but possible effects include stomach upset and changes in blood pressure or heart rate. Because it is in the mustard family, allergic reactions are possible, especially in people allergic to related plants.

Large amounts or prolonged use are not well studied and may carry greater risk, including effects on the heart or thyroid based on early research. Stop using it and seek medical care if you have signs of an allergic reaction, such as rash, swelling, or trouble breathing.

Shepherd's Purse: Reported Adverse Effects

Documented safety reports on Shepherd's Purse from the evidence-graded Natural Medicines (TRC Healthcare) database, shown word-for-word from the licensed record.

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, and palpitations.

  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.
Reports by condition
Hypertension Cardiovascular

Orally, some adverse effects traditionally thought to be associated with shepherd's purse have included hypertension, hypotension,, and palpitations.

  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.
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.

Adverse-effects data: Natural Medicines, Therapeutic Research Center

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. Because doses are not well established and quality can vary between brands, check with a pharmacist or doctor before using it, especially if you take other medicines or have a health condition.

Pregnancy & Breastfeeding

Shepherd's Purse & Pregnancy

Likely Unsafe

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

  1. McGuffin M, Hobbs C, Upton R, Goldberg A, eds. American Herbal Products Association's Botanical Safety Handbook. Boca Raton, FL: CRC Press, LLC 1997.

Shepherd's Purse & Breastfeeding

Insufficient reliable information

Insufficient reliable information available; avoid excessive use.

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

Pregnancy & lactation ratings: Natural Medicines, Therapeutic Research Center

References & further reading

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.
Keep reading

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.

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

Brand directory

Brands that make products with Shepherd's Purse

22 brands in our database make a supplement containing Shepherd's Purse.

Product directory

Supplement products with Shepherd's Purse

73 products in our database contain Shepherd's Purse. Open any to see its full ingredient list and every drug interaction we check.

Pharmacist Counseling Corner

Shepherd's Purse: Common Questions

What is Shepherd's Purse used for, and does it work?
People use Shepherd's Purse for a range of reasons, but according to the Natural Medicines database the current clinical evidence is insufficient to confirm it works for the specific conditions it has been studied for. See the graded list on this page, and talk to your pharmacist or doctor before relying on it for any condition.
Does Shepherd's Purse interact with prescription medications?
Yes. We list 264 medications with a known interaction with Shepherd's Purse. Use the checker above to see how Shepherd's Purse interacts with a specific drug.
How are Shepherd's Purse interactions rated?
Each interaction is graded major, moderate, or minor based on how clinically significant it is and the strength of the evidence behind it. Major interactions are the most serious and are best avoided, or used only under close professional supervision.
Is it safe to take Shepherd's Purse with my medications?
It depends on the specific medication. Some combinations are fine, while others call for monitoring, timing changes, or should be avoided. Check your exact drug above and confirm with your pharmacist or doctor before starting, stopping, or changing anything.
Where does this Shepherd's Purse interaction information come from?
Our interaction data is built on the Natural Medicines database — an evidence-graded reference for vitamins, herbs, and supplements — and is reviewed by licensed HelloPharmacist pharmacists, who may add clinical context.
What is Shepherd's Purse used for?
It is most often used as a traditional remedy for heavy menstrual bleeding and other minor bleeding, and sometimes as a mild diuretic or for digestive complaints. Strong scientific evidence for these uses is limited.
Is Shepherd's Purse safe to take?
It may be tolerated by some adults when used short-term, but human safety data are limited. People with bleeding, heart, blood pressure, or thyroid issues, and anyone facing surgery should check with a doctor first.
Can I use Shepherd's Purse during pregnancy or breastfeeding?
No. It may stimulate the uterus and is not well studied in nursing, so it should be avoided during both pregnancy and breastfeeding.
How is Shepherd's Purse usually taken?
It is commonly taken as a tea, liquid extract, or capsule. Since there is no standardized dose, follow the product label and ask a pharmacist for guidance.

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

Keep exploring

Products that contain Shepherd's Purse

A rotating sample of real supplements in our database that list Shepherd's Purse — open any to see its full ingredients and every drug interaction we check.

See all 73 products with Shepherd's Purse →
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