Is Mugwort Toxic? The Nuance of Herbal Safety

The reason why students of herbal medicine feel like traditional folk knowledge and science are pitted against each other, is because they are, but not perhaps in the way you think. 

When you decontextualize plant medicine, passing on knowledge becomes like a game of telephone. And when hyper-focus on specific aspects of an herb without a holistic framework of knowledge or embodied understanding to balance it, like we so love to do in our modern western biomedical pharmacological approach to medicine, you lose the ability to see the plant for what it actually is: a relational being. This is the reason why there is such a vast array of opinions and contradictory data when it comes to herbs in terms of what is safe and effective. I hear it all the time from beginner students– how do you sort through the riff-raff?

Mugwort (Artemisia vulgaris) is trending on social media at the moment. A conversation around has been circulating recently over a post warning not to trust anyone “casually” recommending mugwort. While nuanced conversation around safety of herbal medicines and accountability amongst practitioners is never a bad thing, these types of over-sensationalized claims dance the line of fear-mongering. This can be a death-knell to ethnobotanical knowledge and cultural continuity. A great many plants, especially over the past few centuries, have fallen out of use due to fear or loss of practical knowledge, and that is very difficult to regain once it’s been lost. Pokeweed, bittersweet nightshade, lobelia ephedra, sassafras, calamus, and comfrey, just to name a few, are examples of plants that most modern practitioners won’t (or legally can’t) work with for this reason. So many of our herbal medicines (and our foods) exist on a spectrum of toxicity that require nuanced understanding and approach to be safe. 

Yes, some herbs are safer than others. Some herbs have high toxicity concerns, and require more care and a higher level of expertise to work with. But broad brushing herbs and trying to fit them into neat boxes never gets us very far. If budding herbalists spent their time learning their materia medica by digging into the underlying principles of herbalism needed to develop deep, embodied relationships with the herbs, and then taking their time to actually forge those relationships, there would be a lot less hype and hysteria. It is the difference between a phrase being passed down the game of telephone and the handing down of a tangible item to be directly observed; each individual has a unique perspective and reaction to the item, leaving room in the margins for relational interpretation, not blatant misinformation.

Mugwort has some specific safety information that people should know before working with it, yes, but it is an herb that has long been used in food as well as medicine. It is a safe, effective remedy when applied correctly with respect for the plant and the individuals receiving its medicine. Artemisia vulgaris has a long history of medicinal and culinary use across Europe and Asia for at least the past two thousand years. In East Asian medicine, the dried leaves are widely used in moxibustion, where burning mugwort is applied near acupuncture points to warm meridians and improve circulation. In Japan, where Japanese mugwort (Artemisia princeps) is known as yomogi, it is incorporated into seasonal foods such as herbal rice cakes and spring dishes, reflecting a long tradition of integrating medicinal plants into cuisine. In Vietnamese culture, mugwort (ngải cứu) is a common household herb used both medicinally and culinarily. It is frequently cooked with eggs in dishes such as mugwort omelets to support digestion, circulation, and postpartum recovery. In European folk traditions, mugwort has historically been associated with digestive bitters, protective rituals, and seasonal celebrations, when it was worn in garlands or used in ceremonial fires. Each of these culturally specific practices varied in their season demonstrate that plant use is shaped by local ecological knowledge, culinary traditions, and ritual meaning, not only pharmacology. In these traditions, harvest timing reflected practical knowledge of plant chemistry and physiological action; young, spring or early summer leaves were preferred for culinary use due to the tenderness of the leaves and their less better flavor. 

The primary safety concern associated with mugwort relates to thujone, a monoterpene that acts as a GABA-A receptor antagonist and can produce neurotoxic effects at high doses. However, toxicity risk depends strongly on a number of factors, especially on dose and preparation method. Concentrated preparations and/or inappropriate use, for example ingestion of the essential oil, can produce seizures in some individuals, and this risk if higher in children. It is contraindicated in pregnancy due to its emmenagogue (uterine stimulating) effects, and with certain medications, primarily due to its inhibitory effect on CYP1A2 and CYP2C9 liver enzymes.

Thujone concentration increases throughout the season, especially after flowering. Thujone has a bitter flavor. Conversely, the sesquiterpene β-caryophyllene, which has a sharp, peppery profile, is more concentrated in young growth and then declines as the plant matures. These are only two of the phytoconstituents out of the dozens known to exist in the plant, but they illustrate the immense amount of information direct, organoleptic observation impart. Mature mugwort, higher in thujone, has a higher antimicrobial activity and is a stronger circulatory stimulant making it appropriate medicinally for specific applications, such as topical use. Young mugwort is safer toxicologically and can be consumed in food-quanities, with constituents like the β-caryophyllene imparting healing qualities like inflammation and immune modulation, pain relief, and strong antioxidant action. If you understand plants as dynamic, living beings in the context of their environment, it comes as no surprise that mugwort is richer in antioxidant constituents when it’s younger, because the plant needs those antioxidants to protect against intense early-stage environmental and metabolic stresses. This is the kind of knowledge that makes you more effective as an herbalist, but also builds up a better immunity to false claims and half-baked hysteria. 

In addition to understanding the dynamics of the phytochemical make-up of the plant throughout its growth, we also can look at the solubility and bioavailability of its various constituents in different extraction and application methods. Thujone is virtually insoluble in water. So while it's possible there may be trace amounts of thujone in a traditionally-prepared tea, the safety profile for this type of application is entirely different than that of say, a tincture, because thujone is quite alcohol soluble. The very nature of herbalism makes it difficult to make broad statements like “mugwort is toxic” because, in what context are we discussing the plant? Young fresh leaves or mature leaves and seeds? Wet climate, dry climate, harvested after a drought? Harvested in the heat of the day or early morning? Dried leaves, a smoke, a tincture– what abv? A tea–what ratio, water temperature, and how long was it brewed? An essential oil–what dilution? A salve, a steam? I could go on. Some of these nuances will make insignificant differences in terms of safety profile, while others are so significant you might as well be talking about a whole other plant. And on that note, are we even discussing the same mugwort? Because there are 500 Artemisia species and at least a dozen species within the Artemisia genus that are referred to as and applied similarly to “mugwort.” 

Generalization can make our lives easier, and there are general patterns we can learn to recognize and apply practically. But relying on shortcuts and existing in a conceptual abstraction untethered from practical validation is a sure-fire way to dunning-kruger your way into the limelight, and nobody wants that. 

This decontextualization is a product of disconnect. It’s what happens when we fashion medicine into “substance” instead of a relationship. We focus only on the herb as a set of chemicals… but not even all of them chemicals, just “active constituents,” out of the hundreds or thousands that make up the plant and even worse, we treat those select constituents as those they each exist in a vacuum within the plant, as opposed to the complex, damn-near-magical synergistic relationship they form together to create a greater whole. Additionally, another layer of relationship we erase, we pretend that all plants of the same species are identical, as if clones produced in a controlled environment, as opposed to the diverse and highly variable individuals that grow and develop in response to their environment. The act of acknowledging plants as sovereign living beings is as much scientific as it is spiritual. And then, of course, we frequently fail to address the fact that once these herbs interface with our own bodies, a metabolic synergy creates yet another layer of relationship, which is difficult to study in a controlled environment, both for logistical and ethical reasons. En vivo studies of herbs are hard to come by, so frequently substituted are studies on rats or monkeys or brine shrimp.

Traditional knowledge is scientific knowledge. That means that, for the most part, folk knowledge comes from science. That science, though generally not performed in a lab, relies on the observation of effects of a process over many generations. Of course, there are exceptions. There are superstitions, anecdotes, isolated experiences, and just general misinformation, that get perpetuated in old wives tales or legends that are passed along without adequate fact checking or peer review. This is evident enough in modern herbalism, where ridiculous and non-factual details about plants get passed along from person to person until a few too many people accept it as truth. This kind of thing is more common in decontextualized, disembodied cultures where information gets freely among many without the direct application of those concepts (what some refer to as “airmchair herbalism”). In the modern era of high speed internet, social media, and AI, this effect is amplified and accelerated.

Scientific knowledge is also, of course, scientific, but it is not faultless. There are many, many ways a scientific study on herbal medicine can go wrong. The most frequent places all stem from a lack of understanding of foundational principles of herbal medicine; improper application, dose, duration, etc. for the intended use. The other issue is of the plant matter itself; quality, variability amongst plant part, season, or growth phase, and extraction form all can play a huge role in the outcome of the study, and are frequently entirely overlooked or not well understood. So you can have a study, protected from all the whims and misgivings of folk knowledge by a strict, scientific framework, that is completely useless in any facet except to create rifts in the media and confuse consumers and beginner herbalists, simply because the studies are not formulated with real-world herbal insight. 

So are traditional knowledge and scientific study irreconcilable? On the contrary, they rely on each other to make sense and to be applicable on a practical level. A good scientific study acknowledges both historical and modern ethnobotanical context and ecological context. It acknowledges the plant as something beyond the sum of its parts, in relationship with its environment on every level, in every phase of its journey from harvest to ingestion. Is there information to glean from studies that fail to do this? Often, yes. But we can’t base whole opinions, much less policy, on this type of research. And similarly, when we rely on folk knowledge, we need to carefully examine it and determine its validity. This can be more challenging than verifying modern science, primarily due to the incomprehensible scale of erasure of traditional and indigenous knowledge and practices. It is also due in part to our over-intellectualization and cultural disconnect with knowledge-ways beyond euro-centric methods. There is an understanding of the plants that will never be quantitatively measured, and that comes from… you guessed it, relationship.