Herb & supplement monograph

Canadian Fleabane Drug Interactions, Uses, Safety & More

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

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

But these pages have grown well beyond that into a full monograph — what Canadian Fleabane 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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Canadian Fleabane 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 Canadian Fleabane drug interaction appears low for most people, since the only documented concern is theoretical. None of the listed interactions are rated major, and every one of them traces back to a single lab-based finding rather than studies in people.

Interactions deserving the most attention

The one group worth real attention is anticoagulant and antiplatelet drugs, which include blood thinners such as warfarin, aspirin, clopidogrel, and heparin. Lab research shows Canadian Fleabane can make blood platelets less sticky, so in theory it could add to the effect of these medicines and raise bleeding risk. Because blood thinners work within a narrow margin, we treat even a theoretical additive effect with respect, especially for anyone whose clotting is closely monitored.

What the rest of the list means

Although the list of interacting medications looks long, it comes almost entirely from that single blood-thinning concern applied across many drugs. The effect has only been seen in lab studies, not in people, so most of these combinations may never cause a real problem. A long list here reflects caution, not proven harm.

Check your medications against Canadian Fleabane

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

Interaction report

Drugs that interact with Canadian Fleabane

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

2,830 drugs
AbciximabReoPro› AbrocitinibCibinqo› AcenocoumarolSintrom› Acetaminophen, AspirinGemnisyn› Acetaminophen, Aspirin, CaffeineExcedrin, Excedrin Extra Strength, Excedrin Migraine› Acetaminophen, IbuprofenCombogesic› Acetylsalicylic AcidEntrophen› Alteplase, TpaActilyse, Activase› Aluminum Hydroxide, Aspirin, Codeine Phosphate, Magnesium HydroxideAscriptin Codeine #2› Aluminum Hydroxide, Aspirin, Magnesium HydroxideAscriptin› Anacaulase-bcdbNexoBrid› AnagrelideAgrylin› AnisindioneMiradon› Antithrombin IiiThrombate III› ApixabanEliquis› ArgatrobanArgatroban› AspirinAngettes 75, ASA, Asaphen, Aspirin, Caprin, Cartia +8 more› Aspirin, Aluminum Hydroxide, Codeine Phosphate, Magnesium HydroxideAscriptin Codeine #3› Aspirin, ButalbitalAxotal› Aspirin, Butalbital, CaffeineFiorinal› Aspirin, Butalbital, Caffeine, Codeine PhosphateFiorinal w/ Codeine› Aspirin, Butalbital, Caffeine, PhenacetinMarnal› Aspirin, CaffeineAnacin› Aspirin, Caffeine, Codeine PhosphateAnacin w/ Codeine› Aspirin, Caffeine, Dihydrocodeine BitartrateSynalgos DC› Aspirin, Caffeine, Dover's PwdAcedoval, Dovacet› Aspirin, Caffeine, HydrocodoneDamason-P› Aspirin, Caffeine, Isobutylallylbarbituric Acid, PhenacetinLanorinal› Aspirin, Caffeine, OrphenadrineInvagesic, Invagesic Forte, Norgesic, Norgesic Forte, Orphengesic, Orphengesic Forte› Aspirin, Caffeine, Phenacetin, PropoxypheneMargesic Comp. 65›
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 Canadian Fleabane 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 Canadian Fleabane affects

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

All 1 drug category Canadian Fleabane interacts with
Anticoagulant/antiplatelet Drugs
Anticoagulant/Antiplatelet Drugs

Theoretically, Canadian fleabane might cause additive effects and side effects when used with anticoagulant or antiplatelet drugs. Canadian fleabane has been shown to inhibit platelet aggregation in vitro.
Some anticoagulant/antiplatelet drugs include aspirin, clopidogrel (Plavix), dalteparin (Fragmin), enoxaparin (Lovenox), heparin, ticlopidine (Ticlid), warfarin (Coumadin), and others.

Likelihood Possible Evidence D
Monograph

Canadian Fleabane: Uses, Safety & Side Effects

Medically reviewed by · Reviewed June 2026 ·
The bottom line

Canadian Fleabane is a common North American weed used in traditional medicine for diarrhea, minor bleeding, and urinary issues, but high-quality human studies are lacking. Because its safety has not been well studied, it is best to talk with your pharmacist or doctor before using it, and to avoid it during pregnancy and breastfeeding.

Scientific name
Erigeron canadensis
Family
Asteraceae
Part used
Aerial parts (leaves, stems, flowers) and the essential oil
Common forms
Tea, tincture, dried herb, liquid extract, essential oil
People commonly use it for
  • Diarrhea
  • Minor bleeding
  • Urinary complaints
  • Digestive upset
  • Sore throat and inflammation

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

Safety at a glance
OverallUse caution

Used traditionally, but human safety data are limited so use cautiously.

PregnancyInsufficient reliable information

Insufficient reliable information is available; avoid using.

Read the full pregnancy detail
BreastfeedingInsufficient reliable information

Insufficient reliable information is 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

Canadian Fleabane (Erigeron canadensis, also classified by some as Conyza canadensis) is a tall, weedy plant in the daisy family. It is native to North America but now grows as a common weed in fields, roadsides, and disturbed ground across many parts of the world.

The above-ground parts of the plant have been used in folk and traditional medicine for a long time. People have made teas, tinctures, and extracts from the leaves and flowers, and an essential oil can be steam-distilled from the plant. Traditionally it was used for digestive complaints, diarrhea, and minor bleeding.

Uses & effectiveness

Canadian Fleabane has a long history of traditional use, but there is very little modern, high-quality human research to confirm that it works for any health condition. Most of what we know comes from traditional practice, laboratory tests, and a small number of animal studies.

People have commonly used it for:

  • Diarrhea and digestive upset — a traditional use, but not proven in well-designed human studies.
  • Minor bleeding — historically applied or taken to help slow bleeding, with little scientific support.
  • Urinary complaints — used as a folk remedy, again without strong evidence.
  • Sore throat and inflammation — based on traditional use rather than proven benefit.

Overall, the evidence is considered weak or insufficient. You should not rely on Canadian Fleabane in place of proven treatments for any medical condition.

How it works

The plant and its essential oil contain compounds such as flavonoids, terpenes (including limonene), tannins, and small amounts of essential oils. In laboratory studies, some of these compounds show antioxidant, anti-inflammatory, or antimicrobial activity.

The tannins in the plant may help explain its traditional use for diarrhea, since tannins can have a drying, astringent effect on tissues. However, these proposed mechanisms come mostly from test-tube and animal research. We do not have good evidence showing how, or whether, these effects translate into real benefits in people.

Safety & precautions

Canadian Fleabane has been consumed traditionally, but its safety has not been carefully studied in modern clinical trials. Because of this, it should be used with caution.

People with allergies to plants in the daisy/aster family (such as ragweed, marigolds, daisies, and chrysanthemums) may react to Canadian Fleabane and should avoid it. The essential oil is concentrated and should never be swallowed unless directed by a qualified professional.

Pregnancy and breastfeeding: There is not enough reliable safety information for these situations, so it is best to avoid Canadian Fleabane if you are pregnant or breastfeeding. Children, older adults, and people with chronic illness or kidney problems should also speak with a healthcare professional first.

Side effects

Because Canadian Fleabane has not been well studied, its full side effect profile is not known. Reported or possible effects include allergic reactions (skin rash, itching, or breathing problems), especially in people sensitive to daisy-family plants.

The essential oil and concentrated extracts may irritate the skin, mouth, or stomach. Stop using it and seek medical care if you notice signs of an allergic reaction, such as swelling, hives, or difficulty breathing.

Dosing

There is no established, science-based standard dose for Canadian Fleabane. Traditional preparations such as teas and tinctures vary widely in strength, and product labels differ from brand to brand.

If you choose to use a commercial product, follow the directions on the label and do not exceed them. The essential oil is very concentrated and is not meant to be taken by mouth without professional guidance. Always check with your pharmacist or doctor before starting Canadian Fleabane, especially if you take other medicines or have a health condition.

Pregnancy & Breastfeeding

Canadian Fleabane & Pregnancy

Insufficient reliable information

Insufficient reliable information is available; avoid using.

Canadian Fleabane & Breastfeeding

Insufficient reliable information

Insufficient reliable information is 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 references that drive our Canadian Fleabane 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. Saluk-Juszczak J, Olas B, Pawlaczyk I, Gancarz R, Wachowicz B. Effects of the extract from Conyza canadensis on human blood platelet aggregation. Gen Physiol Biophys 2007;26(2):150-2.
  2. Olas B, Saluk-Juszczak J, Pawlaczyk I, et al. Antioxidant and antiaggregatory effects of an extract from Conyza canadensis on blood platelets in vitro. Platelets 2006;17(6):354-60.
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

Pharmacist Counseling Corner

Canadian Fleabane: Common Questions

Does Canadian Fleabane interact with prescription medications?
Yes. We list 122 medications with a known interaction with Canadian Fleabane. Use the checker above to see how Canadian Fleabane interacts with a specific drug.
How are Canadian Fleabane 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 Canadian Fleabane 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 Canadian Fleabane 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 Canadian Fleabane used for?
It has been used in traditional medicine for diarrhea, digestive upset, minor bleeding, and urinary complaints. These uses are based on tradition, and strong human evidence to support them is lacking.
Is Canadian Fleabane safe to take?
It has been used traditionally, but its safety has not been well studied in modern research. Use it cautiously, avoid the concentrated essential oil by mouth, and check with your pharmacist or doctor first.
Can I use Canadian Fleabane during pregnancy or breastfeeding?
No. There is not enough safety information, so it is best to avoid it while pregnant or breastfeeding.
Who should avoid Canadian Fleabane?
People allergic to daisy-family plants like ragweed, marigolds, or chrysanthemums may react to it and should avoid it. Children, pregnant or breastfeeding people, and those with chronic illness should talk with a healthcare professional first.

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

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