Since yarrow is a member of the Asteraceae family, anyone with allergies to other plants in that family (e.g., marigolds, ragweed, daisies) has a higher risk of having an allergic reaction to yarrow. Yarrow contains thujone, which is responsible for some of its antibacterial properties, but also runs the risk of neurotoxicity when consumed (at best estimate) in doses greater than 3–7 mg of thujone per day.[1][2][3] More clinical evidence is required to better understand the safety of consuming thujone-containing products. While skin rashes are the most frequently reported adverse response to yarrow (and are believed to be due to guaianolides), the majority of the few clinical studies have excluded participants who might experience herb-drug interactions, which would reduce the number of reported adverse reactions.[2]
What are yarrow’s main drawbacks?
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•Last Updated: May 16, 2025
Yarrow may cause allergic reactions in individuals sensitive to plants in the Asteraceae family (e.g., marigolds, ragweed, daisies) and can lead to neurotoxicity if consumed in high doses due to its thujone content. Additionally, skin rashes are a common adverse response, but clinical studies often exclude people at risk for herb-drug interactions, which means that adverse effects are potentially underreported.