Recently, a fellow oiler and friend of mine reached out to me and asked me about the uses for fleabane essential oil. I had to admit, I did not know much about the secondary metabolites of horseweed and its applications. So, I did what I usually do as a naturopathic essential oils doctor. I started a website and journal search to learn more.

Below is the information I gathered about this interesting essential oil.

A Plant of Many Names

Canadian Fleabane (Erigeron canadensis, Conzya canadensis) is a member of the Asteraceae family. It has many common names including Horseweed, Eastern Daisy Fleabane, Canadian fleabane, Fleabane daisy, colt’s tail, butter weed, fireweed, blood-stanch, cow’s tail, bitter weed, flea wort, sweet scabious, morning widow, and frostweed. Even more interesting, this plant has two taxonomic names, with Conzya canadensis being its homotypic synonym. (source, source)

The Center for Agriculture and Bioscience International (CABI) described why this plant is dually classified by name as follows:

The species was first described by Linnaeus as Erigeron canadensis in 1753, and transferred to the genus Conyza in 1943 by Cronquist. C. canadensis is a clearly defined species and is not nomenclaturally confused with any other related species, unlike several others within the genus (see datasheets on C. bonariensis and C. sumatrensis). It is, however, still widely referred to by its older name, Erigeron canadensis. Thebauld and Abbott (1995) noted that C. canadensis was the only diploid species of five invasive European species tested, and was more closely related to the genus Erigeron than the other taxa. This supports a hypothesis that C. canadensis is older in evolutionary terms.

I discovered quickly that being aware of all its namesakes was quite important when trying to find reference articles on the oil

The Compounds Found in Fleabane

Fleabane is native to North America, but it is now common in South America and Europe. There are several different species of Erigeron, (source, source, source, source, source, source, source) which, along with its chemotype and location, would impact which constituents are found in the plant and oil. (source, source, source)

Medicinal Plants of South Asia, reiterates this concept in their summary chapter on Horseweed:

Horseweed (Conyza canadensis L.) belongs to the Asteraceae family, and its genus is Conyza, which contains about 60 species that are annual herbaceous plants widely distributed in subtropical and tropical regions of the globe. This plant contains essential oil, triterpenoids, phenolic acids, sphingolipids, acetylenes, and steroids. The chemical composition and yield of essential oil extracted from this plant depends upon the part of the plant used for oil extraction, origin, and ontogenesis phase.

That being understood, the main compounds reported in Conzya canadensis are flavonoids, bitters, tannins and gallic acids, and its volatile oils (including limonene, terpineol, and linalool). Most sources list limonene as the main constituent among various chemotypes. (source, source, source, source, source, source, source)

A 2012 article in Scientific World Journal states, “The essential oil of juvenile and mature herbs collected in Washington State (USA) was previously analyzed by Hrutfiord et al.; twenty-five constituents, including monoterpenes, sesquiterpenes, and acetylenes were identified, and the predominance of limonene (67.25%) was confirmed.”

Proposed and Traditional Uses

According to an online herbal encyclopedia of fleabane, the native uses for this plant were vast. They included support for the respiratory, urinary, gastrointestinal, and musculoskeletal systems. One traditional use led to an interesting story behind how it came upon its common name:

Native American tribes, including the Mesquakies, powdered the flowers to make a snuff that, when sniffed, caused sneezing that would break up a head cold or catarrh. The Lakotas made a tea from the entire plant to treat children with sore mouths and adults who had difficulty urinating. Other uses included teas for rheumatism, lameness, and stomach disorders. The blossoms were also mixed with brains, gall, and spleen of a buffalo, and then rubbed on the hide to bleach it in the tanning process. The Navajo used fleabane in lotions for body pain and headaches. The Cheyenne used the whole plant in boiling water to inhale the vapors. It was also boiled to make steam for sweat lodges and burned to create a smoke that warded off insects. It was also used to clear intestinal parasites and, hence, the common name.

The Natural Medicine Database reports similar modern indications:

Orally, Canadian fleabane is used for bronchitis, diarrhea, menorrhagia, and cancer. It is also used for granuloma annulare, sore throat, urinary tract infections (UTIs), gout, rheumatoid arthritis (RA), fever, and parasitic worms. Topically, Canadian fleabane is used to stop bleeding.

In the Medicinal Plants of South Asia, the authors further reiterate a variety of applications:

It has also been recommended for bladder disorders. It cures colon trouble, summer complaint, and cholera. It is also beneficial in kidney gravel, diabetes, hemorrhages, fevers, cystitis, nosebleeds, tuberculosis, bronchitis, coughs, and dropsy.

Finally, a monograph from the Eclectic School of Medicine summarizes herbal experts’ experience with the plant for:

Respiratory, cough with mucous discharge, Digestion, Diarrhea, Lack of appetite, Kidneys and Bladder problems, menstrual problems, postpartum bleeding, capillary or passive hemorrhage.

Studies on Fleabane Essential Oil

I wasn’t able find clinical research evidence for Canadian fleabane oil. Even the Natural Medicine Database was sparse. There was a lot more information for the whole plant extracts; however, for its anti-inflammatory, anti-coagulant, and antioxidant effects. (source, source, source, source) Interesting, I also found this plant had several publications with results on testing its resistance to the pesticide glyphosate. There were various effects on its resiliency. (source, source)

Below are what properties of fleabane oil I did find in the peer-reviewed articles.

Antifungal: In one in vitro study, a Hungarian version of fleabane was used to assess the antibacterial and antifungal properties of the oil. The results indicated antifungal properties, but no action against the bacteria strains.

Insect Repellent: The essential oil was found to have larvicidal and insecticidal activity against mosquitos. Interesting larvicidal activity, as measured by assays, was correlated with limonene content.

As you can see, the studies are sparse. Still, it doesn’t mean that we can’t infer more about this oil based on its compounds.

Looking at the Compounds

As reported in the literature, Canadian fleabane most likely has some antifungal and anti-pest properties. This makes sense based on its linalool, limonene, and terpineol content. Although we know that an oil is much more than the sum of its parts and has synergy, we can also make some assumptions on other effects based on its chemical profile.

As Robert Tisserand wrote in his post regarding the functional group theory (FGT) of oils:

Marco Valussi, Andrea Cont, Joy Bowles and I spent two years writing a comprehensive explanation for why FGT is not a useful tool to learn or predict essential oil properties. Instead, we propose an approach that more accurately reflects the science and that is, in the end, simpler. Studying the properties of constituents can be extremely useful, but these should be studied individually, rather than in (functional) groups. Abandoning FGT does not mean the therapeutic activities of a constituent need to change, so long as they are based on evidence of effect, and not on assumption.

Canadian fleabane has high content and percentage of limonene. This compound has been shown to have many benefits including supporting immune, metabolic, digestive, and cellular health. Canadian fleabane also contains a very intriguing mix of sesquiterpenes and monoterpenes, which have neuroprotective and additional immune-enhancing properties.


In my opinion, Canadian fleabane would be a good option to try adding to your outdoor oils sprays to keep bugs and critters in their place. Based on its traditional uses and array of compounds, this oil most likely will benefit overall resilience and vitality, mood, and respiratory, nervous, and cellular functions.

I am interested in hearing your experience with fleabane.

Mental Health Resources

*If you are experiencing a mental health crisis and/or are suicidal, please seek professional mental health support:

  • The National Suicide Prevention Lifeline (U.S.) — Call 1-800-273-TALK (8255)
  • Crisis Text Line — Text HOME to 741741 to connect with a crisis counselor
  • Lifeline Crisis Chat — Chat online with a specialist who can provide emotional support, crisis intervention and suicide prevention services at


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Disclaimer: This material is for information purposes only and is not intended to diagnose, treat, or prescribe for any illness. You should check with your doctor regarding implementing any new strategies into your wellness regime. These statements have not been evaluated by the FDA. (Affiliation link.)

According to experts and the World Health Organization (WHO), there is no approved standard of care treatment, cure, or preventative for COVID-19. Supportive measures and containment are in full force as a result. Please see the CDC website and your state’s website for more information and updates. They also state when to contact your physician related to symptoms and travel history, exposures. Please read my more detailed article on this subject here.

This information is applicable ONLY for therapeutic quality essential oils. This information DOES NOT apply to essential oils that have not been tested for purity and standardized constituents. There is no quality control in the United States, and oils labeled as “100% pure” need only to contain 5% of the actual oil. The rest of the bottle can be filled with fillers and sometimes toxic ingredients that can irritate the skin. The studies are not based solely on a specific brand of an essential oil, unless stated. Please read the full study for more information.

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