Motherwort Safety: Cardiac Interactions and Pregnancy

Table of Contents

1. Safety Summary
2. Pregnancy: A Firm Contraindication
3. Why the Name Misleads About Pregnancy
4. Breastfeeding
5. Why This Population Is the Wrong One
6. Beta-Blockers and Other Rate-Slowing Drugs
7. Digoxin and Antiarrhythmic Drugs
8. Blood-Pressure Medication
9. Sedatives, Alcohol and Other Calming Herbs
10. Antiplatelet and Anticoagulant Drugs
11. Direct Side Effects
12. Product Quality and Species Substitution
13. Who the Research Raises Concerns For
14. What Makes an Interaction Check Useful
15. Evidence Tiers at a Glance
16. Key Research Papers
17. Connections
18. Featured Videos

Safety Summary

The short version, before the detail:

• Pregnancy — contraindicated. The European Medicines Agency (EMA) monograph states that motherwort is “not to be used in pregnancy”. Traditional uterine stimulant and emmenagogue, and the plant's name works against this message.
• Breastfeeding — no safety data. The EMA monograph states that safety during breastfeeding (lactation) “has not been established”.
• Cardiac medication — no human interaction data. The EMA monograph lists no reported interactions, but in isolated rabbit hearts a motherwort extract slowed the beat and prolonged the PQ interval, and in heart cells it blocked calcium channels (Ritter and colleagues, 2010). Additive rate slowing with beta-blockers and other rate-limiting drugs is therefore plausible; digoxin and antiarrhythmics have narrow margins and bad failure modes.
• Sedatives and alcohol — additive drowsiness. This is the best-supported interaction the herb has.
• Anticoagulants and antiplatelet drugs — a concern on theoretical grounds only.
• Direct side effects — mostly digestive, driven by extreme bitterness, plus drowsiness.
• Uncharacterised palpitations — the EMA lists the palpitations use only “after serious conditions have been excluded by a medical doctor”. An electrocardiogram (ECG) is the test that shows the rhythm, and palpitations with chest pain, breathlessness or fainting are signs that hospitals treat as urgent. See the palpitations page and its red-flag list.

One framing point that shapes everything below. Motherwort has an acceptable traditional safety record — it is registered in the European Union as a traditional herbal medicinal product, a status that requires documented long-standing use without serious harm. It does not have a modern pharmacovigilance dataset, systematic interaction studies, or human pharmacokinetic data. "No documented cases" therefore means something much weaker than it sounds: nobody is systematically looking. Where the consequence of an interaction is an arrhythmia or a bleed, an unmeasured risk is not the same as no risk.

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Pregnancy: A Firm Contraindication

The European Medicines Agency’s 2010 motherwort monograph states that it is “not to be used in pregnancy” and “contraindicated during pregnancy”, and notes that adequate tests on reproductive toxicity have not been performed. This is the single firmest safety fact on any motherwort page on this site, and it does not depend on modern research at all — it comes out of the tradition's own account of the plant.

Motherwort was classed by European herbalists as an emmenagogue — a plant used to bring on a delayed or scanty menstrual period — and as a uterine stimulant, given after childbirth to help the womb contract back down. Both are uterine-activating roles. A plant chosen precisely because it can nudge the uterus into activity carries, by the tradition’s own logic, a risk during a pregnancy. Standard herbal safety references and European regulatory documentation both list pregnancy as a contraindication, and this is the reason given.

Notice the shape of the argument. It does not claim there is trial evidence that motherwort causes miscarriage — there is no such trial, and there never will be, because it would be unethical to run. It claims something more defensible: a herb whose traditional purpose includes uterine stimulation, with no human safety data in pregnancy, is listed as contraindicated in pregnancy. Absence of evidence is not reassurance when the outcome at stake is a pregnancy. Very large doses have also been associated historically with uterine bleeding, which points in the same direction.

The same logic extends to two adjacent situations:

• Trying to conceive. A cycle that looks late may already be an early pregnancy, at exactly the stage a woman would not yet know. An emmenagogue is a plant traditionally used to bring on a period, which is exactly the concern at that stage.
• Uncertainty. The contraindication covers pregnancy from its first days, including the weeks before it is confirmed.

If you are pregnant and have palpitations, breathlessness, chest discomfort, or severe anxiety, those symptoms have causes of their own. Pregnancy changes cardiac physiology considerably — blood volume and heart rate both rise — and while most palpitations in pregnancy turn out benign, some do not. Palpitations together with chest pain, breathlessness or fainting are signs that hospitals treat as urgent.

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Why the Name Misleads About Pregnancy

This deserves its own section because the failure mode is so predictable.

"Motherwort" reads, to any English speaker, as a herb for mothers. It sounds nurturing. Add the well-documented postpartum tradition — the herb genuinely was given to women after childbirth — and the natural inference is that motherwort is a pregnancy-friendly herb. It is not. The tradition is for labour and after delivery, and the properties that made it useful then are precisely the properties that rule it out during pregnancy.

The other names make the point more clearly than the common one does. "Mother" here means the womb: in older English medical writing "the mother" was a term for the uterus, so motherwort meant the womb-herb, not the mother's herb. The old folk name throw-wort refers to the throes of labour. Neither name promises safety in pregnancy; both point at the uterus.

Now put that together with why people arrive at this plant. Palpitations, breathlessness and anxiety are all common in pregnancy. Motherwort is widely recommended online for palpitations and anxiety. The name reassures. That is a complete, foreseeable route by which a pregnant woman takes a contraindicated uterine stimulant while trying to settle her heart — which is why the warning appears on every motherwort page in this section rather than being tucked into one.

Motherwort is one of the clearest examples on this site of a common name implying a safety profile the plant does not have. Comfrey, pennyroyal and blue cohosh are others where the folk name or reputation understates the risk. The general lesson holds: a friendly name is not safety data.

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Breastfeeding

The EMA monograph states that motherwort’s safety during breastfeeding (lactation) “has not been established”. The reason is plain: there is no meaningful safety data. Nobody has established whether motherwort's constituents pass into breast milk, in what quantity, or with what effect on an infant.

That the traditional postpartum use existed does not resolve this. It was practised in a setting with a very different risk calculus, no way to detect a subtle effect on a newborn, and no expectation of the evidence standard now applied to anything a nursing mother takes. Two specific concerns are worth naming: the herb's sedative activity, which is the action with the most preclinical support, would be unwelcome in an infant; and the bitter diterpenes could plausibly affect the taste of milk and feeding.

For any question about a substance during breastfeeding, the standard reference is LactMed, the US National Library of Medicine's drugs-and-lactation database, hosted on NCBI Bookshelf.

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Why This Population Is the Wrong One

Most herb-interaction discussions are abstract because the overlap between herb users and drug users is modest. Motherwort is the opposite case, and it is worth being explicit about why.

The herb's headline traditional indication is palpitations and cardiac symptoms. Who has those? Disproportionately: people over sixty, people with hypertension, people with diagnosed arrhythmias, people after a heart attack, people with heart failure. That population is heavily medicated, and medicated specifically with the drug classes motherwort might plausibly interact with — rate-slowing drugs, antihypertensives, antiarrhythmics, digoxin, anticoagulants.

Two consequences follow.

First, the interaction probability is not low even if each individual interaction is uncertain. If a large share of users take at least one relevant drug, then even modest per-interaction risk aggregates into something real.

Second, the consequences are asymmetric. An interaction between a herb and, say, a topical eczema treatment is an inconvenience. An interaction that pushes a heart rate too low, destabilises an antiarrhythmic, or adds to an anticoagulant produces bradycardia, arrhythmia, or bleeding. These are the failure modes people are hospitalised for.

The general framework for this reasoning is set out in the cardiology literature — Tachjian, Maria and Jahangir's review of herbal product use and potential interactions in patients with cardiovascular disease, published in the Journal of the American College of Cardiology in 2010, is the standard reference, and the broader picture appears in Izzo and Ernst's systematic review of interactions between herbal medicines and prescribed drugs in Drugs in 2009. Neither is about motherwort specifically. Both explain why interactions matter most for people with heart disease.

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Beta-Blockers and Other Rate-Slowing Drugs

Tier: theoretical, with preclinical support. No human interaction data; the EMA monograph lists no reported interactions.

Drugs involved: beta-blockers (bisoprolol, metoprolol, atenolol, propranolol, carvedilol and others), rate-limiting calcium channel blockers (diltiazem, verapamil), ivabradine, and digoxin in its rate-controlling role.

The mechanistic case for concern is the most substantive of any motherwort interaction. Ritter and colleagues, in Planta Medica in 2010, reported that a refined extract of Leonurus cardiaca, given into the coronary arteries of isolated rabbit hearts, prolonged the PQ interval and lengthened the time between beats (a slower rate), and that in isolated heart cells it blocked L-type calcium channels. Miłkowska-Leyck and colleagues, in the Journal of Ethnopharmacology in 2002, reported that the isolated glycoside lavandulifolioside reduced heart rate, prolonged the P-Q and Q-T intervals and lowered blood pressure in animals. Both findings are exactly what would predict additive bradycardia on top of a rate-slowing drug.

What is missing is the human half. Nobody has measured what happens to heart rate in a person on bisoprolol who starts motherwort tincture, and there are no published case reports of symptomatic bradycardia from the combination. Calling this "documented" would be false.

The stakes are what make this matter. Bradycardia matters because a heart rate that falls too low produces fatigue, dizziness, exercise intolerance and, at the extreme, syncope — and syncope in an older person means falls and fractures. Many people on beta-blockers already sit in the fifties. An extra rate-slowing agent of unknown strength adds to a rate that is already slowed, and tincture concentrations vary several-fold between products, so the dose taken is unknown.

A resting pulse counted before and after starting shows whether the rate has dropped. Dizziness, unusual fatigue, breathlessness on exertion or near-fainting after starting are the signs of a heart rate that has fallen too low (bradycardia); fainting, chest pain or breathlessness at rest are signs that hospitals treat as urgent.

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Digoxin and Antiarrhythmic Drugs

Tier: theoretical. No measured interaction; the concern rests on the drugs’ narrow safety margins.

Drugs involved: digoxin; antiarrhythmics including amiodarone, flecainide, sotalol, propafenone, dronedarone.

The argument here is about margins rather than mechanism. Digoxin has one of the narrowest therapeutic windows in common use — the gap between an effective level and a toxic one is small, blood levels are monitored for exactly that reason, and digoxin toxicity presents with nausea, visual disturbance, confusion and, characteristically, arrhythmias. Antiarrhythmic drugs share the same uncomfortable property: they are given to suppress rhythm disturbances and, at the wrong concentration or in the wrong electrical environment, they cause them.

Into that environment, adding a botanical extract with demonstrated electrophysiological activity in cardiac tissue, at an unknown dose, with unknown pharmacokinetics, adds an unmeasured factor to drugs whose safe range is narrow — and motherwort has no demonstrated antiarrhythmic effect in humans.

Two secondary considerations. Motherwort has not been characterised for effects on P-glycoprotein or the cytochrome P450 enzymes that govern the handling of many of these drugs, so transport- and metabolism-level interactions cannot be ruled out either way. And electrolytes matter enormously to antiarrhythmic safety — low potassium and low magnesium both promote arrhythmia — so anything causing diarrhoea, which bitter herbs can, has an indirect route to trouble. See Potassium and Arrhythmia and Magnesium and Palpitations.

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Blood-Pressure Medication

Tier: theoretical, with preclinical and weak human support. Home blood-pressure readings show any added effect directly.

Drugs involved: angiotensin-converting enzyme inhibitors (ACE inhibitors), angiotensin receptor blockers, calcium channel blockers, diuretics, alpha-blockers, beta-blockers.

This is the one interaction with any human data at all, and the data are weak. The small open-label study by Shikov and colleagues in Phytotherapy Research in 2011 reported modest blood-pressure reductions with a Leonurus cardiaca oil extract in patients with hypertension, anxiety and sleep disturbance — with no placebo group, so the effect may not be real. Lavandulifolioside lowered blood pressure in animals.

Taken together, a mild additive antihypertensive effect is plausible. Some readers may see that as a benefit rather than a risk. Two cautions apply. Additive lowering matters most in people already near the floor — older people, those on several agents, those prone to postural drops — where the result is dizziness on standing and a fall risk. And the herb’s blood-pressure effect is unquantified in a condition where the treatment target is a number: if pressure improves, nobody can tell how much came from the herb, which complicates any later medication change.

For people who take antihypertensives and use motherwort, a written record of home blood-pressure readings shows whether pressure is falling and by how much. See Hypertension, and Hawthorn and Blood Pressure for a related herb with more trial data.

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Sedatives, Alcohol and Other Calming Herbs

Tier: preclinical plus pharmacological class effect — the best-supported interaction motherwort has. Additive drowsiness is expected, and the EMA monograph states that motherwort “may impair ability to drive and use machines”.

Substances involved: benzodiazepines (diazepam, lorazepam, alprazolam), Z-drugs (zopiclone, zolpidem), sedating antihistamines, opioids, some antidepressants and antipsychotics, gabapentin and pregabalin, alcohol, and other sedative herbs including valerian, passionflower, lemon balm, chamomile, hops and kava.

This one rests on more than analogy. Sedative activity is the action with the most consistent preclinical support in L. cardiaca: a butanolic extract of the plant reduced movement (spontaneous locomotor activity) in animals, although the isolated compound lavandulifolioside did not (Miłkowska-Leyck and colleagues, 2002), modified dry extracts showed psychotropic activity in animal behavioural testing (Koshovyi and colleagues, Plants, 2021), and the analgesic testing reported by Rezaee-Asl and colleagues in 2014 is consistent with central depressant activity. Additive sedation between agents that each depress the central nervous system is a general and reliable pharmacological principle.

Practical consequences: more drowsiness than expected, impaired coordination and reaction time, and impaired judgement about how impaired you are — which is the reason this matters for driving and machinery. In older adults, added sedation also raises the risk of falls and worsens confusion.

Two notes for herb users specifically. Multi-herb "calm" or "sleep" formulas frequently combine motherwort with valerian, passionflower and hops, so you may be stacking several sedatives without noticing. And alcohol counts — including the alcohol in the tincture itself, which is minor at normal doses but not zero.

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Antiplatelet and Anticoagulant Drugs

Tier: theoretical. No human data.

Drugs involved: warfarin, direct oral anticoagulants (apixaban, rivaroxaban, edoxaban, dabigatran), aspirin, clopidogrel, ticagrelor, prasugrel, and heparins.

The basis for the caution is general rather than specific. Motherwort's constituents include a substantial flavonoid fraction, and various plant flavonoids affect platelet function in laboratory preparations. There is no controlled human study of motherwort and platelet function, no study of motherwort and the international normalised ratio in warfarin users, and no published case series of bleeding. This is genuinely theoretical.

The reason to take a theoretical concern seriously here is again the population. Atrial fibrillation is a common cause of the palpitations that lead people to motherwort, and most people with atrial fibrillation above a risk threshold are anticoagulated. So the overlap between motherwort users and anticoagulant users is substantial by construction. Bleeding on an anticoagulant is not a minor adverse event: gastrointestinal and intracranial bleeding are the reasons these drugs are managed carefully.

Practical facts: anticoagulation clinics and pharmacists ask about herbal products as a routine part of checking for interactions, and in warfarin users a change in effect shows up on the international normalised ratio (INR) blood test. The US National Library of Medicine’s warfarin information lists bleeding that will not stop, coughing or vomiting blood or material that looks like coffee grounds, red or black tarry stools, and pink, red or dark brown urine among the bleeding signs; these are signs that hospitals treat as urgent. There is also the historical association of very large motherwort doses with uterine bleeding, which sits in the same general territory.

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Direct Side Effects

Setting interactions aside, the herb itself has a modest and mostly predictable side-effect profile.

• Gastrointestinal upset — nausea, stomach discomfort, loose stools. This is the commonest complaint and it is driven by the herb's extreme bitterness and its labdane diterpene content. It is dose-related, so lower doses produce less of it. Diarrhoea is not trivial in someone on cardiac drugs, because it disturbs electrolytes.
• Drowsiness — consistent with the sedative activity described above.
• Dizziness or lightheadedness — plausible if heart rate or blood pressure fall, particularly on standing.
• Contact skin irritation — handling the fresh plant can irritate sensitive skin. Motherwort's spiny calyces are mechanically prickly as well.
• Uterine bleeding at very large doses — a historical association, and part of the reason for the dosing caution and the bleeding-disorder exclusion.
• Allergy — motherwort is in the mint family (Lamiaceae), alongside lemon balm, sage, mint and thyme. Cross-reactivity within a plant family is not a rule; the EMA monograph lists allergy (hypersensitivity) to motherwort itself as a contraindication.
• Taste aversion — not a medical adverse effect, but the commonest practical reason people stop. Motherwort tea is genuinely hard to drink.

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Product Quality and Species Substitution

A safety page has to cover the product as well as the plant, because herbal supplements are regulated far more loosely than medicines in most countries.

Species substitution is the specific issue for motherwort. Two plants share the common name: European Leonurus cardiaca and East Asian Leonurus japonicus (yi mu cao). They differ chemically. The marker alkaloid stachydrine is present in both: Kuchta and colleagues, in Fitoterapia in 2014, measured 0.09–1.01% in East Asian samples and up to 1.55% in four European L. cardiaca samples. The alkaloid leonurine, which carries most of the genus's dramatic pharmacology, is chiefly a japonicus constituent, present in European cardiaca at low, variable and analytically disputed levels. Supplement marketing routinely attributes leonurine pharmacology to European motherwort. A label that gives the Latin species name shows which of the two plants a product contains; a label that says only “motherwort” does not.

Other quality points that bear on safety:

• Preparation type is not interchangeable. A tea, an ethanolic tincture, a powdered capsule and the oil extract used in the Shikov study are chemically different products. Dosing or safety experience with one does not transfer.
• Tincture concentrations vary several-fold between manufacturers. "Twenty drops" is not a dose without knowing the product.
• No standardisation exists. There is no accepted standardised extract of motherwort, so there is no way to know how much active material any product contains.
• Contamination and adulteration are general risks in the botanical supply chain — heavy metals, pesticide residues, and misidentified plant material. Published batch test results are the only way a buyer can see whether a product was checked for them.
• Wild harvesting. Motherwort is a common roadside weed, and roadside plants accumulate vehicle-derived contaminants. Plants gathered away from traffic carry less of this, and misidentification is a separate risk for anyone gathering it.

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Who the Research Raises Concerns For

• People who are pregnant, possibly pregnant, or trying to conceive — contraindicated in pregnancy (EMA).
• People who are breastfeeding — safety not established (EMA).
• Children and teenagers — no safety or dosing data; the EMA monograph states that use under 18 has not been established because of a lack of adequate data and is not recommended.
• People with a diagnosed slow heart rhythm (bradyarrhythmia), heart block, or a pacemaker fitted for a slow rhythm.
• People with low blood pressure or a tendency to faint on standing.
• People taking digoxin or an antiarrhythmic drug.
• People with a bleeding disorder, or taking an anticoagulant.
• People with unexplained palpitations that have not been checked — not because the herb is known to harm, but because the EMA lists the palpitations use only after serious conditions have been excluded, and an electrocardiogram is the test that shows what the rhythm is.
• People with heavy menstrual bleeding of unknown cause — because of the historical association with uterine bleeding.
• People facing surgery — because of the sedative and theoretical bleeding effects. A 2001 review of herbal medicines and surgery (Ang-Lee and colleagues, JAMA) describes sedative herbs strengthening anaesthetics and other herbs adding to bleeding, and concludes that herbal medicine use is to be asked about and recorded before an operation.
• People with a known allergy to motherwort (an EMA contraindication) or to other mint-family (Lamiaceae) plants.

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What Makes an Interaction Check Useful

Many people do not mention herbal products to their doctor or pharmacist, often because they expect dismissal. A few things make an interaction check more useful.

• The actual product. The label tells a pharmacist more than the name does — species, preparation, concentration, alcohol content, and any other herbs in the formula.
• What it is being used for. "I have flutters that were checked and were benign extra beats, and I want something for the anxiety around them" is a completely different conversation from "I want a natural heart medicine."
• Pharmacists. Community pharmacists are often the best-placed people for interaction questions and are easier to reach than a cardiologist.
• The person’s own drug list. The useful question is "does this interact with my medications?" rather than "is this safe?"
• Stopping prescribed medication has risks of its own. Stopping a beta-blocker abruptly can cause rebound tachycardia (a fast heart rate) and worse; stopping an anticoagulant in atrial fibrillation raises stroke risk immediately.
• New symptoms. Dizziness, faintness, unusual fatigue, breathlessness, bruising or bleeding after starting a herb are the signs of the interactions described above; fainting, chest pain and bleeding that will not stop are signs that hospitals treat as urgent.

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Evidence Tiers at a Glance

• Pregnancy contraindication — based on the traditional uterine-stimulant and emmenagogue classification plus absence of human safety data; stated as a contraindication in the EMA monograph. Not derived from a trial, and does not need to be.
• Breastfeeding — safety not established (EMA), for absence of data.
• Additive sedation — preclinical (animal sedative and psychotropic findings for L. cardiaca) plus a general pharmacological class effect. The best-supported interaction.
• Additive rate slowing — preclinical: isolated-tissue electrophysiology and animal heart-rate reduction. No human confirmation, no case reports.
• Additive blood-pressure lowering — preclinical animal data plus one small uncontrolled human study.
• Digoxin and antiarrhythmic concern — theoretical, argued from narrow therapeutic margins rather than a measured interaction.
• Antiplatelet and anticoagulant concern — theoretical, argued from flavonoid content. No human data.
• Gastrointestinal side effects — traditional and widely reported in practice; dose-related.
• Documented case-report evidence of serious harm — none identified. Read that as reflecting an absence of systematic surveillance, not as a safety guarantee.

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Key Research Papers

Most links are PubMed topic searches, so they return the current literature rather than one frozen record; entries checked against their PubMed record link to it directly.

1. Tachjian A, Maria V, Jahangir A. Use of herbal products and potential interactions in patients with cardiovascular diseases. Journal of the American College of Cardiology, 2010. The standard cardiology reference for why this patient group is the wrong one for unquantified botanicals. PubMed: herbal products and cardiovascular interactions
2. Izzo AA, Ernst E. Interactions between herbal medicines and prescribed drugs: an updated systematic review. Drugs, 2009. The broad systematic picture of herb-drug interaction evidence and its gaps. PubMed: herb-drug interaction systematic review
3. Ritter M, Melichar K, Strahler S, et al. Cardiac and electrophysiological effects of primary and refined extracts from Leonurus cardiaca L. Planta Medica, 2010. The isolated-tissue basis for the rate-slowing interaction concern: in isolated rabbit hearts the refined extract prolonged the PQ interval and lengthened the cycle length, and in heart cells it blocked L-type calcium channels. PubMed PMID: 19918711
4. Miłkowska-Leyck K, Filipek B, Strzelecka H. Pharmacological effects of lavandulifolioside from Leonurus cardiaca. Journal of Ethnopharmacology, 2002. The isolated compound reduced heart rate, prolonged the P-Q and Q-T intervals and lowered blood pressure in animals; unlike the butanolic extract it came from, it did not reduce spontaneous movement — the basis for the rate and blood-pressure concerns. PubMed PMID: 11891090
5. Shikov AN, Pozharitskaya ON, Makarov VG, et al. Effect of Leonurus cardiaca oil extract in patients with arterial hypertension accompanied by anxiety and sleep disorders. Phytotherapy Research, 2011. The only human blood-pressure signal; small, open-label, no placebo arm. PubMed: Leonurus cardiaca and blood pressure
6. Koshovyi O, Raal A, Kireyev I, et al. Phytochemical and psychotropic research of motherwort (Leonurus cardiaca L.) modified dry extracts. Plants, 2021. Whole-extract sedative and psychotropic activity in animals — the sedation-interaction basis. PubMed: Leonurus cardiaca psychotropic extracts
7. Rezaee-Asl M, Sabour M, Nikoui V, et al. The study of analgesic effects of Leonurus cardiaca L. in mice by formalin, tail flick and hot plate tests. International Scholarly Research Notices, 2014. Animal work consistent with central depressant activity. PubMed: Leonurus cardiaca analgesic testing
8. Wojtyniak K, Szymański M, Matławska I. Leonurus cardiaca L. (motherwort): a review of its phytochemistry and pharmacology. Phytotherapy Research, 2013. Includes the traditional contraindications and the state of the safety literature. PubMed: Leonurus cardiaca review
9. Fierascu RC, Fierascu I, Ortan A, et al. Leonurus cardiaca L. as a source of bioactive compounds: an update of the European Medicines Agency assessment report. BioMed Research International, 2019. The link between the herb's chemistry and Europe's formal safety and traditional-use assessment. PubMed: Leonurus cardiaca EMA assessment
10. Kuchta K, Ortwein J, Hennig L, Rauwald HW. ¹H-qNMR for direct quantification of stachydrine in Leonurus japonicus and L. cardiaca. Fitoterapia 2014;96:8-17. Stachydrine measured at 0.09–1.01% in East Asian samples and up to 1.55% in European L. cardiaca — the analytical basis for the species-substitution section. PubMed PMID: 24704554
11. Literature on herbal medicine use in pregnancy and its safety, including reviews of emmenagogue and uterine-stimulant botanicals. The general framework behind the pregnancy contraindication. PubMed: herbal medicines in pregnancy
12. Literature on herbal supplement use and perioperative risk, including bleeding and sedation, which underlies the surgery concern. PubMed: herbal supplements and surgery
13. Literature on adulteration, misidentification and contamination in botanical products, which is why naming the species on the label matters. PubMed: botanical adulteration and authentication
14. Broader current searches: PubMed: Leonurus cardiaca safety and PubMed: motherwort drug interaction.

External Resources

1. NCBI Bookshelf — hosts LactMed (drugs and lactation) and LiverTox, both standard safety references.
2. NCCIH — US National Center for Complementary and Integrative Health; herb safety and interaction summaries.
3. MedlinePlus — consumer drug and supplement information from the US National Library of Medicine.
4. European Medicines Agency — publishes the motherwort herbal monograph and assessment report, including its contraindications.
5. American Heart Association — patient information on arrhythmias, anticoagulation and blood pressure.
6. NHS (United Kingdom) — medicines information and guidance on when heart symptoms need urgent care.

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Connections

• All Herbs
• Motherwort
• Motherwort Benefits Hub
• Motherwort for Palpitations
• Motherwort for Anxiety
• Menstrual and Postpartum Tradition
• Atrial Fibrillation
• Arrhythmia
• Hypertension
• Supraventricular Tachycardia
• Palpitations
• Heart Palpitations
• Potassium and Arrhythmia
• Magnesium and Palpitations
• Postpartum Hemorrhage
• Postpartum Depression
• Hawthorn and Blood Pressure
• Valerian
• Passionflower
• Lemon Balm
• Cardiology

Safety Note and Disclaimer

This page is health education, not medical advice. The European Medicines Agency’s motherwort monograph states that it is contraindicated in pregnancy and that its safety during breastfeeding has not been established; it is a traditional uterine stimulant and emmenagogue, its common name misleadingly suggests it is a pregnancy-friendly herb, and an early pregnancy may not yet be known while trying to conceive. The same monograph reports no interactions and states that motherwort may impair the ability to drive and use machines. The concerns with beta-blockers, other rate-slowing drugs, antihypertensives, digoxin, antiarrhythmics, sedatives, antiplatelet drugs and anticoagulants rest on animal and isolated-heart studies — in isolated rabbit hearts a motherwort extract slowed the beat and prolonged the PQ interval, and in heart cells it blocked calcium channels (Ritter and colleagues, 2010) — and there are no human interaction data. Stopping or reducing prescribed cardiac medication carries risks of its own: a rebound fast heart rate after a beta-blocker is stopped abruptly, and a higher stroke risk when an anticoagulant is stopped in atrial fibrillation. Most of the interactions described here are theoretical or preclinical rather than documented in case reports — but in a population this heavily medicated, with arrhythmia and bleeding as the failure modes, that uncertainty is not the same as reassurance. The EMA lists palpitations as a traditional use only after serious conditions have been excluded; an electrocardiogram is the test that shows the rhythm, and palpitations with chest pain, breathlessness, fainting or near-fainting are signs that hospitals treat as urgent.

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