Tansy.
A bitter aromatic roadside herb carrying thujone and parthenolide-type lactones. Traditional use was as a bitter and as an insect-deterring strewing herb.
- Category
- Herb
What Tansy is, and what it does.
- Does it work
- Suits people exploring traditional bitter herbs in small supervised amounts. Not for use in pregnancy, and not a plant to pick and dose yourself.
- How much to take
- No dose figure is on record, and thujone content swings widely plant to plant, so a weight of herb tells you little. This is a question for a practitioner.
- Time to feel it
- Nobody has published a time course in people. The bitterness registers on the tongue at once. Nothing else here has a measured timeline.
- The first dose
- Day one is a bitter, camphor-like taste and little else on record. Handling the fresh plant can bring on a rash in people sensitive to the daisy family.
- With regular use
- No study has followed weeks of daily use in people. Regulators cap thujone in food and drink, which is why continuous use is not how this herb is handled.
- How well tolerated
- Thujone blocks a brain chloride channel at high exposure, and the plant is contraindicated in pregnancy. Daisy-family allergy is common. Check with a clinician.
- How it feels
- Sharply bitter and camphorous. Beyond the taste, nobody has published what a person experiences from it.
- The overlooked benefit
- Chemotype beats species name here. Some plants are low in thujone and led by camphor or borneol, so a chemical assay tells you far more than the label does.
The proof, claim by claim.
These words describe the research, not the molecule's worth. Research strength is how much work stands behind one claim, and it is never a product score.
- traditional use as a bitter aromatic herbNarrative review
- thujone content and its regulated limits in food and drinkNarrative review
- sesquiterpene lactone content and contact allergy potentialNarrative review
- insect and nematode deterrence by the whole plantIn vitro study
- chemotype variation in essential oil compositionNarrative review
Why these belong in the same formula. Each row says what the basis is, from settled biochemistry through to a trial that measured the pair.
Tansy essential oil is dominated by thujone in most European chemotypes, and thujone blocks the GABA-A chloride channel rather than opening it. That puts it in direct opposition to anything working through GABA-A signalling. At sufficient exposure this loss of inhibitory tone is what drives thujone's seizure risk, which is the reason thujone content is legally capped in food and drink.
Valerian constituents act to enhance GABAergic tone while thujone opposes it. Combining them means one botanical is working against the other at the same target. Beyond the wasted effort, the combination masks the early sedation cues that would otherwise flag excessive thujone exposure.
Tansy is loaded with sesquiterpene lactones, notably parthenolide-type compounds, which are the classic Asteraceae contact allergens. Stacking it with another Asteraceae botanical adds to the same sensitiser load. Anyone who reacts to ragweed, chrysanthemum or arnica should approach tansy with the same caution.
Tanacetum parthenium and Tanacetum vulgare are close botanical relatives and both carry parthenolide-class lactones, which is exactly why they get confused on labels and in wild harvest. They are not interchangeable: common tansy carries substantial thujone that feverfew does not. A product naming only Tanacetum without the species should be regarded as unidentified.
Both botanicals irritate gastric mucosa through different routes, salicylate in willow and volatile ketones plus lactones in tansy. Combining them raises the chance of nausea and upper gut discomfort. The interaction is on tolerability, not on any shared therapeutic target.
Alpha-thujone is cleared mainly by cytochrome P450 hydroxylation, principally CYP2A6 with contributions from other isoforms, and the parent compound is the more active species. Anything altering that clearance shifts exposure to the parent. Silymarin has modest effects on several P450 isoforms in laboratory systems, so the direction in a person is not predictable. This is a reason for caution rather than a recommendation either way.
Nothing specific on file for Tansy. Match the label to the daily amount above, and tell your doctor what you take.
Not medical advice. Show the label to your pharmacist.What Tansy actually does.
It shuts down the brain's main brake system, which is why high doses cause seizures.
Your liver breaks it down fast, and how fast decides how much reaches the brain.
Regulators put a hard ceiling on this compound in anything you drink.
The same compounds that give it activity are the ones that cause skin reactions in sensitive people.
Where Tansy comes from.
It is a yellow button-flowered roadside weed that carries a compound called thujone. How much varies wildly plant to plant, and thujone is the reason regulators cap it in food. Not for use in pregnancy, and not something to self-dose from a wild-picked plant.
Made from a plant. What ends up in the capsule tracks the harvest, so batch testing and a stated marker matter more here than with a made molecule.
A perennial Asteraceae herb native to Eurasia and widely naturalised in North America, where it is listed as a noxious weed in several states
Aerial parts are either shade dried for herb use or distilled fresh to capture the volatile ketone fraction
Steam distillation yields the thujone-rich essential oil. Aqueous or hydroethanolic extraction pulls the flavonoid and lactone fraction instead
Because chemotype variation is severalfold, responsible material is assayed for alpha and beta thujone rather than assumed from species identity
Supplied as loose herb, essential oil, or a freeze-dried extract
The forms it comes in.
The essence, in one line each.
- In vitro shoot culture of Tanacetum vulgare produced tissue with a defined secondary metabolite profile, offering a controlled route to standardised plant material.In vitro study. Devrnja N et al., 2021 (Protoplasma). PMID 33244630 ↗
- Lyophilised Tanacetum vulgare extract was formulated into intraruminal bolus and granule forms and evaluated in a veterinary delivery context.Animal study. Vanaga A et al., 2025 (Veterinary World). PMID 40926855 ↗
These are the studies our verdict leans on, chosen from the 2 we read for Tansy. The full linked list is below.
FDA Disclaimer: These statements have not been evaluated by the Food and Drug Administration. This information is for educational purposes only and is not intended to diagnose, treat, cure, or prevent any disease. Consult your healthcare provider before starting any supplement regimen.