Herb & supplement monograph

Yellow Loosestrife Drug Interactions, Uses, Effectiveness, Safety & More

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

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

But these pages have grown well beyond that into a full monograph — what Yellow Loosestrife 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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Reviewed by licensed pharmacists Sourced from Natural Medicines
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Interaction report

Drugs that interact with Yellow Loosestrife

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

We don’t currently list any known drug interactions for Yellow Loosestrife. This doesn’t guarantee none exist — always confirm with your pharmacist before combining supplements with your medications.

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 Yellow Loosestrife combination — clinical detail, likelihood, evidence level, and citations.
  • Content is reviewed by licensed HelloPharmacist pharmacists — see our data sources and editorial standards.
Monograph

Yellow Loosestrife: Uses, Safety & Side Effects

Medically reviewed by · Reviewed June 2026 ·
The bottom line

Yellow loosestrife (Lysimachia vulgaris) is a traditional European herb used mostly for diarrhea, minor bleeding, and mouth or throat irritation. There is very little modern scientific evidence to confirm it works, and its safety has not been well studied, so it should be used cautiously and avoided in pregnancy and breastfeeding.

Scientific name
Lysimachia vulgaris
Family
Primulaceae
Part used
Aerial parts (leaves, stems, and flowers)
Common forms
Tea (infusion), tincture, dried herb, occasionally topical preparations
People commonly use it for
  • Diarrhea and digestive upset
  • Minor wounds and bleeding
  • Mouth and throat irritation
  • Mild gastrointestinal complaints

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

Safety at a glance
OverallLimited data

Human safety data are very limited, so use cautiously and talk to a healthcare provider first.

PregnancyInsufficient reliable information

Insufficient reliable information available; avoid using.

Read the full pregnancy detail
BreastfeedingInsufficient reliable information

Insufficient reliable information available; 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

Yellow loosestrife (Lysimachia vulgaris) is a tall, leafy plant with bright yellow flowers. It grows in damp places such as riverbanks, marshes, and ditches across Europe and parts of Asia, and it has spread to some areas of North America.

It belongs to the primrose family and should not be confused with purple loosestrife (Lythrum salicaria), which is a different plant. In traditional European folk medicine, the leaves, stems, and flowers were dried and made into teas or used on the skin.

People have long used yellow loosestrife for digestive problems like diarrhea, for stopping minor bleeding, and for soothing irritation in the mouth and throat. Today it is not a widely studied or commonly sold supplement.

How it works

Yellow loosestrife contains plant compounds such as tannins and flavonoids. Tannins are astringent, meaning they can tighten and dry tissues, which is the traditional reason the plant was used for diarrhea and minor bleeding.

Flavonoids and other compounds in many plants have antioxidant properties in laboratory tests. However, most of what is known about yellow loosestrife's possible effects comes from its chemistry and from how related plants behave, not from studies in people.

Because solid research is lacking, the exact way it might affect the body remains largely unproven.

Effectiveness

Does Yellow Loosestrife 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 Yellow Loosestrife, 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 Diarrhea
Rating & evidence shown verbatim from Natural Medicines

Although there is interest in using oral yellow loosestrife for diarrhea, there is insufficient reliable information about the clinical effects of yellow loosestrife for this condition.

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

Although there is interest in using oral yellow loosestrife for menorrhagia, there is insufficient reliable information about the clinical effects of yellow loosestrife for this condition.

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

Although there is interest in using oral yellow loosestrife for minor bleeding such as nose bleeds, there is insufficient reliable information about the clinical effects of yellow loosestrife 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

The safety of yellow loosestrife has not been well studied in modern research. Because of this, it is hard to say how safe it is, especially when used regularly or in large amounts.

Herbs high in tannins may cause stomach upset in some people, particularly when taken on an empty stomach or in strong amounts. People with existing stomach or bowel problems should be cautious.

Pregnancy and breastfeeding: There is not enough information to consider it safe. To be on the safe side, women who are pregnant or breastfeeding should avoid it.

Children, older adults, and people with chronic health conditions should talk to a pharmacist or doctor before trying it. Make sure you have correctly identified the plant, since it can be confused with other species.

Side effects

Reported side effects are not well documented because the herb has not been studied much. Based on its tannin content, possible effects include stomach upset, nausea, or constipation, especially with strong or frequent use.

As with any plant product, an allergic reaction is possible. Stop using it and seek medical care if you notice a rash, swelling, trouble breathing, or other signs of an allergy.

Dosing

There is no established standard dose for yellow loosestrife. Modern science has not determined a safe or effective amount.

If you choose to use a product, follow the directions on the label and do not exceed them. Because doses and product quality can vary widely, it is best to check with a pharmacist or doctor before starting, and to use it only for short periods.

Pregnancy & Breastfeeding

Yellow Loosestrife & Pregnancy

Insufficient reliable information

Insufficient reliable information available; avoid using.

Yellow Loosestrife & Breastfeeding

Insufficient reliable information

Insufficient reliable information available; avoid using.

DISCLAIMER: This tool is intended for informational purposes only, and should not be interpreted as specific medical advice. Patients should consult with a qualified healthcare provider before making decisions about therapies and/or health conditions.

© 2026 Therapeutic Research Center

Pregnancy & lactation ratings: Natural Medicines, Therapeutic Research Center

References & further reading

The 2 sources that drive our Yellow Loosestrife monograph — publicly available pages from reputable medical and government organizations. Every link was verified to work before publishing.

  1. Herbs at a Glance — NIH National Center for Complementary and Integrative Health Source
  2. Herbs and Supplements — MedlinePlus (U.S. National Library of Medicine) Source
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.

Pharmacist Counseling Corner

Yellow Loosestrife: Common Questions

What is Yellow Loosestrife used for, and does it work?
People use Yellow Loosestrife 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 Yellow Loosestrife interact with prescription medications?
We do not currently list any known drug interactions for Yellow Loosestrife. This does not guarantee that none exist, so always confirm with your pharmacist before combining it with your medications.
How are Yellow Loosestrife 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 Yellow Loosestrife 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 Yellow Loosestrife 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 Yellow Loosestrife used for?
It is a traditional European herb used mostly for diarrhea, minor bleeding, and irritation of the mouth and throat. These uses are based on folk practice, not strong scientific proof.
Is Yellow Loosestrife the same as purple loosestrife?
No. Yellow Loosestrife (Lysimachia vulgaris) is in the primrose family, while purple loosestrife (Lythrum salicaria) is a completely different plant. They are sometimes confused because of similar names.
Is Yellow Loosestrife safe to take?
Its safety has not been well studied in people, so it is hard to say. Use it cautiously, in small amounts, and talk to a healthcare provider first.
Can I use it during pregnancy or while breastfeeding?
No. There is not enough safety information, so it is best to avoid Yellow Loosestrife if you are pregnant or breastfeeding.

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

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