Herb & supplement monograph

Bugleweed Drug Interactions, Uses, Effectiveness, Safety & More

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

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

But these pages have grown well beyond that into a full monograph — what Bugleweed 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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Bugleweed 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 Bugleweed drug interaction appears low for most people, with one clear exception for anyone taking thyroid medication. None of the listed interactions are rated major, and every one of them traces back to a single concern: bugleweed's possible effect on thyroid hormones.

Interactions deserving the most attention

Thyroid hormone medications deserve the most attention here. Bugleweed may weaken their effect by blocking the step the body uses to turn the hormone into its active form, and this concern rests on some human evidence, not lab work alone. Because thyroid replacement works within a narrow margin, even a modest change could show up in thyroid levels and how a person feels, so this combination is worth flagging to a prescriber.

What the rest of the list means

The list of interacting medications looks longer than the story really is, because all of them share this same thyroid-related mechanism. The supporting evidence is limited and partly theoretical, so a meaningful effect is plausible rather than firmly proven. For people who do not take thyroid medicines, nothing else in bugleweed's profile stands out as a concern.

Check your medications against Bugleweed

Based on HelloPharmacist’s Bugleweed interaction data and reviewed under our editorial standards.

Interaction report

Drugs that interact with Bugleweed

16 medications have a known interaction with Bugleweed, graded by severity. Select any drug for the full evidence-based detail.

2,830 drugs
Conjugated EstrogensCenestin, Enjuvia, Premarin, Premarin Vaginal Cream
Moderate Thyroid Hormone

Theoretically, bugleweed may alter thyroid function.

Read the full Bugleweed + Conjugated Estrogens interaction
Desiccated Thyroid ExtractWesthroid, WP Thyroid
Moderate Thyroid Hormone

Theoretically, bugleweed may alter thyroid function.

Read the full Bugleweed + Desiccated Thyroid Extract interaction
Desiccated Thyroid Extract (prescription Drug)Nature-Throid, Thyrar
Moderate Thyroid Hormone

Theoretically, bugleweed may alter thyroid function.

Read the full Bugleweed + Desiccated Thyroid Extract (prescription Drug) interaction
DextrothyroxineCholoxin
Moderate Thyroid Hormone

Theoretically, bugleweed may alter thyroid function.

Read the full Bugleweed + Dextrothyroxine interaction
Human Chorionic Gonadotropin (hcg)Pregnyl
Moderate Thyroid Hormone

Theoretically, bugleweed may alter thyroid function.

Read the full Bugleweed + Human Chorionic Gonadotropin (hcg) interaction
LevothyroxineEltroxin, Estre, Euthyrox, Levo-T, Levolet, Levothroid +5 more
Moderate Thyroid Hormone

Theoretically, bugleweed may alter thyroid function.

Read the full Bugleweed + Levothyroxine interaction Levothyroxine drug page: uses, dosage & side effects
Levothyroxine SodiumErmez, Thyquidity, Tirosint-Sol
Moderate Thyroid Hormone

Theoretically, bugleweed may alter thyroid function.

Read the full Bugleweed + Levothyroxine Sodium interaction
Levothyroxine, LiothyronineArmour Thyroid
Moderate Thyroid Hormone

Theoretically, bugleweed may alter thyroid function.

Read the full Bugleweed + Levothyroxine, Liothyronine interaction
LiothyronineCytomel
Moderate Thyroid Hormone

Theoretically, bugleweed may alter thyroid function.

Read the full Bugleweed + Liothyronine interaction Liothyronine drug page: uses, dosage & side effects
LiotrixEuthroid 1, Euthroid 1/2, Euthroid 3
Moderate Thyroid Hormone

Theoretically, bugleweed may alter thyroid function.

Read the full Bugleweed + Liotrix interaction Liotrix drug page: uses, dosage & side effects
Liotrix, T4/t3Euthroid 2
Moderate Thyroid Hormone

Theoretically, bugleweed may alter thyroid function.

Read the full Bugleweed + Liotrix, T4/t3 interaction
MenotropinsMenopur, Repronex
Moderate Thyroid Hormone

Theoretically, bugleweed may alter thyroid function.

Read the full Bugleweed + Menotropins interaction
OspemifeneOsphena
Moderate Thyroid Hormone

Theoretically, bugleweed may alter thyroid function.

Read the full Bugleweed + Ospemifene interaction Ospemifene drug page: uses, dosage & side effects
Testosterone UndecanoateAndriol, Aveed, Jatenzo, Kyzatrex
Moderate Thyroid Hormone

Theoretically, bugleweed may alter thyroid function.

Read the full Bugleweed + Testosterone Undecanoate interaction Testosterone Undecanoate drug page: uses, dosage & side effects
ThyroglobulinProloid
Moderate Thyroid Hormone

Theoretically, bugleweed may alter thyroid function.

Read the full Bugleweed + Thyroglobulin interaction
Thyroid HormoneEtwon
Moderate Thyroid Hormone

Theoretically, bugleweed may alter thyroid function.

Read the full Bugleweed + Thyroid Hormone interaction
"phentolamineOraVerse, Rogitine, Ryzumvi › 6-mercaptopurinePurinethol › Ado-trastuzumab EmtansineKadcyla › AbacavirZiagen › Abacavir Sulfate, Dolutegravir, LamivudineTriumeq › Abacavir, LamivudineEpzicom › AbaloparatideTymlos › AbametapirXeglyze › AbarelixPlenaxis › AbciximabReoPro › AbemaciclibVerzenio › Abiraterone › Abiraterone AcetateYonsa, Zytiga › AbrocitinibCibinqo ›
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 Bugleweed 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 Bugleweed affects

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

All 1 drug category Bugleweed interacts with
Thyroid Hormone
Thyroid Hormone

Theoretically, bugleweed may alter thyroid function.
Concomitant use of bugleweed may reduce the effects of thyroid hormones by blocking peripheral conversion of thyroxine (T4) to triiodothyronine (T3).

Likelihood Probable Evidence D
Monograph

Bugleweed: Uses, Safety & Side Effects

Medically reviewed by · Reviewed July 2026 ·
The bottom line

Bugleweed is a traditional herb most often used for mild overactive thyroid symptoms and the rapid heartbeat that can come with it, but high-quality human evidence is very limited. Because it may affect thyroid hormones, it should not be used without medical supervision, and it must be avoided in pregnancy and breastfeeding.

Bugleweed
Scientific name
Lycopus virginicus
Family
Lamiaceae
Part used
Aerial parts (leaves, stems, and flowering tops)
Common forms
Tea, tincture, liquid extract, capsules, dried herb
People commonly use it for
  • Mild overactive thyroid symptoms
  • Heart palpitations and rapid heartbeat
  • Anxiety and restlessness
  • Breast pain (mastalgia)
  • Premenstrual symptoms

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

Safety at a glance
OverallUse caution

May affect thyroid function, so use only under the guidance of a healthcare provider.

PregnancyLikely Unsafe

When used orally. Bugleweed has anti-gonadotropic and anti-thyrotropic activity; avoid using.

Read the full pregnancy detail
BreastfeedingPossibly Unsafe

When used orally because it might have anti-prolactin activity; avoid using.

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

Bugleweed refers to plants in the Lycopus genus, including Lycopus virginicus (Virginia bugleweed) and the closely related European species Lycopus europaeus (gypsywort). The North American species Lycopus americanus is sometimes called American bugleweed or water horehound. These are members of the mint family and grow as leafy perennial plants with square stems and small white or pale pink flowers, usually in damp or wetland areas.

The above-ground parts of the plant are harvested and dried for use in teas, tinctures, and capsules. Traditionally, herbalists have used bugleweed for symptoms linked to a mildly overactive thyroid, for a racing or pounding heartbeat, and for nervous tension.

How it works

Bugleweed contains compounds such as lithospermic acid and other plant acids (phenolic compounds), along with flavonoids. Laboratory and animal research suggests these substances may interfere with thyroid hormone activity—for example, by reducing the production or conversion of thyroid hormones and possibly affecting the thyroid-stimulating hormone (TSH) signal.

Some research also suggests bugleweed may lower levels of the hormone prolactin, which is part of why it has been used for breast pain and why it is a concern during breastfeeding.

It is important to know that these mechanisms are mostly based on lab and animal studies. How strongly bugleweed affects hormones in the human body is not well established.

Effectiveness

Does Bugleweed work?

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

Evidence overview · 3 uses evaluated
3 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 Bugleweed, current evidence isn’t strong enough to rate any specific use. The conditions it has been studied for are listed below.

Also studied for 3 conditions — evidence insufficient to rate
Insufficient Reliable Evidence To Rate Hyperthyroidism
Rating & evidence shown verbatim from Natural Medicines

It is unclear if oral bugleweed is beneficial in patients with hyperthyroidism.

Insufficient Reliable Evidence To Rate Insomnia
Rating & evidence shown verbatim from Natural Medicines

Although there is interest in using oral bugleweed for insomnia, there is insufficient reliable information about the clinical effects of bugleweed for this purpose.

Insufficient Reliable Evidence To Rate Premenstrual syndrome (PMS)
Rating & evidence shown verbatim from Natural Medicines

Although there is interest in using oral bugleweed for PMS, there is insufficient reliable information about the clinical effects of bugleweed for this purpose.

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

Because bugleweed may lower thyroid hormone levels, people with underactive thyroid (hypothyroidism) or an enlarged thyroid should avoid it. People taking thyroid medication or who have any thyroid condition should only use it with a doctor's supervision.

Stopping bugleweed suddenly after regular use has been reported to potentially worsen thyroid symptoms, so changes should be made carefully with a provider's help. Anyone scheduled for thyroid testing should tell their doctor, as it may affect results.

Pregnancy: Avoid bugleweed during pregnancy. There is not enough safety information, and its possible hormonal effects make it unsafe. Breastfeeding: Avoid bugleweed while nursing, since it may reduce prolactin and lower milk supply.

Side effects

When used in usual amounts, bugleweed is generally well tolerated by most people, but good safety data are limited. Possible side effects include changes in thyroid function, which could lead to symptoms of an underactive thyroid (tiredness, weight gain, or feeling cold) if taken too long or in high amounts.

Other reported effects may include an enlarged thyroid (goiter) with long-term use and worsening of symptoms if stopped abruptly. Stomach upset is also possible. Stop using it and contact your healthcare provider if you notice unusual symptoms.

Dosing

There is no well-established standardized dose for bugleweed. It is most often taken as a tea, tincture, or liquid extract, and the strength of these products can vary a lot.

Because doses are not standardized and the herb can affect thyroid function, the safest approach is to follow the directions on the product label and to talk with a pharmacist or doctor before starting. Do not exceed the recommended amount, and do not use it long-term without medical supervision.

Pregnancy & Breastfeeding

Bugleweed & Pregnancy

Likely Unsafe

When used orally. Bugleweed has anti-gonadotropic and anti-thyrotropic activity; avoid using.

  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.
  2. Brinker F. Herb Contraindications and Drug Interactions. 2nd ed. Sandy, OR: Eclectic Medical Publications, 1998.
  3. Schulz V, Hansel R, Tyler VE. Rational Phytotherapy: A Physician's Guide to Herbal Medicine. Terry C. Telger, transl. 3rd ed. Berlin, GER: Springer, 1998.

Bugleweed & Breastfeeding

Possibly Unsafe

When used orally because it might have anti-prolactin activity; avoid using.

  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.
  2. Brinker F. Herb Contraindications and Drug Interactions. 2nd ed. Sandy, OR: Eclectic Medical Publications, 1998.
  3. Schulz V, Hansel R, Tyler VE. Rational Phytotherapy: A Physician's Guide to Herbal Medicine. Terry C. Telger, transl. 3rd ed. Berlin, GER: Springer, 1998.
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 Bugleweed 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. Blumenthal M, ed. The Complete German Commission E Monographs: Therapeutic Guide to Herbal Medicines. Trans. S. Klein. Boston, MA: American Botanical Council, 1998.
  2. Schulz V, Hansel R, Tyler VE. Rational Phytotherapy: A Physician's Guide to Herbal Medicine. Terry C. Telger, transl. 3rd ed. Berlin, GER: Springer, 1998.
  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. Brinker F. Herb Contraindications and Drug Interactions. 2nd ed. Sandy, OR: Eclectic Medical Publications, 1998.
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 Bugleweed

17 brands in our database make a supplement containing Bugleweed.

Product directory

Supplement products with Bugleweed

91 products in our database contain Bugleweed. Open any to see its full ingredient list and every drug interaction we check.

Intestinal Soothe & Build by Nature's Sunshine Capsule 100 Capsule(s) Off market View ingredients & interactions Thyroid Calming by Herb Pharm Liquid 4 Fluid Ounce(s) · 120 mL Off market View ingredients & interactions Thyroid Calming by Herb Pharm Liquid 4 fl. Oz. · 118.4 mL Off market View ingredients & interactions Thyroid Calming by Herb Pharm Liquid 4 fl. Oz. · 120 mL Off market View ingredients & interactions Thyroid Calming by Herb Pharm Liquid 2 fl. Oz. · 60 mL Off market View ingredients & interactions Thyroid Calming by Herb Pharm Liquid 1 fl. Oz. · 30 mL Off market View ingredients & interactions Thyroid Calming by Herb Pharm Liquid 4 fl. Oz. · 120 mL Off market View ingredients & interactions Thyroid Calming by Herb Pharm Liquid 2 fl. Oz. · 60 mL Off market View ingredients & interactions Thyroid Calming by Herb Pharm Liquid 1 fl. Oz. · 30 mL Off market View ingredients & interactions Thyroid Calming by Herb Pharm Liquid 4 fl. Oz. · 120 mL Off market View ingredients & interactions Thyroid Calming by Herb Pharm Liquid 4 fl. Oz. · 120 mL Off market View ingredients & interactions Thyroid Calming by Herb Pharm Liquid 2 fl. Oz. · 60 mL Off market View ingredients & interactions Thyroid Calming by Herb Pharm Liquid 1 fl. Oz. · 30 mL Off market View ingredients & interactions Thyroid Calming by Herb Pharm Liquid 1 fl. Oz. · 30 mL Off market View ingredients & interactions Thyroid Calming by Herb Pharm Liquid 4 fl. Oz. · 120 mL Off market View ingredients & interactions Thyroid Calming by Herb Pharm Liquid 1 fl. Oz. · 30 mL Off market View ingredients & interactions Thyroid Calming by Herb Pharm Liquid 1 Fluid Ounce(s) · 29.6 mL Off market View ingredients & interactions Thyroid Calming by Herb Pharm Liquid 1 Fluid Ounce(s) · 30 mL Off market View ingredients & interactions Thyroid Calming Compound by Herb Pharm Liquid 4 fl. Oz. · 118.4 mL Off market View ingredients & interactions
Pharmacist Counseling Corner

Bugleweed: Common Questions

What is Bugleweed used for, and does it work?
People use Bugleweed 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 Bugleweed interact with prescription medications?
Yes. We list 16 medications with a known interaction with Bugleweed. Use the checker above to see how Bugleweed interacts with a specific drug.
How are Bugleweed 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 Bugleweed 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 Bugleweed 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 Bugleweed used for?
It is mainly used in traditional herbal medicine for symptoms of a mildly overactive thyroid, such as a fast or pounding heartbeat, as well as anxiety and breast tenderness. Strong human evidence for these uses is limited.
Is Bugleweed safe to take?
For most healthy adults it is generally well tolerated in small amounts, but it can affect thyroid hormones, so it should be used cautiously and ideally under a healthcare provider's guidance—especially if you have a thyroid condition.
Can I use Bugleweed if I'm pregnant or breastfeeding?
No. Bugleweed should be avoided during pregnancy due to a lack of safety data, and avoided while breastfeeding because it may lower milk production.
Can Bugleweed replace my thyroid medication?
No. Bugleweed is not a substitute for prescribed thyroid treatment. Thyroid disorders need proper diagnosis and monitoring, so talk with your doctor before using any herb for thyroid symptoms.

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

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Products that contain Bugleweed

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See all 91 products with Bugleweed →
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