Butterbur
A migraine-prophylaxis herb whose defining fact is not its efficacy data but its chemistry. The raw plant contains hepatotoxic pyrrolizidine alkaloids, the commercial extracts are defined by having those removed, and the best-known branded product was withdrawn in Germany after hepatobiliary adverse events. Everything about buying this comes down to whether the removal was done and documented.
Butterbur quick facts
| Suggested dose | The migraine literature used 50–75 mg of standardized rhizome extract twice daily. Nothing here should be run without knowing the pyrrolizidine alkaloid specification. |
| How often | Twice daily, as a defined course rather than an indefinite habit |
| Who it's for | People with frequent migraine who have discussed prophylaxis with a clinician and want the herbal option, with liver monitoring. |
The certificate of analysis is the thing being bought. An extract that does not state a pyrrolizidine alkaloid limit is not a gentler version of one that does — it is an unmeasured version. Never use a home tea or tincture of the raw plant. If it is used at all, it is used with a clinician, with liver enzymes checked before and during, and stopped at once for jaundice, dark urine, right upper quadrant pain or unexplained fatigue. Hepatobiliary adverse events are why the leading branded extract was withdrawn in Germany, and that history is the most important fact about this herb. Asteraceae cross-reactivity applies for anyone with ragweed or chrysanthemum allergy.
How Butterbur actually works
The active constituents are the sesquiterpene esters petasin and isopetasin. In trigeminal afferent preparations they reduce evoked calcitonin gene-related peptide release, with the pharmacology pointing at inhibition of TRPA1 and TRPV1 channels on those neurons — the same CGRP pathway that the modern monoclonal antibodies and gepants target from the other end. Separate work supports calcium-channel blockade and inhibition of leukotriene synthesis, which is the more likely route for the allergic rhinitis effect of the leaf extracts. Sitting alongside all of this in the raw plant are pyrrolizidine alkaloids, which are not incidental impurities but plant constituents; they are bioactivated by hepatic CYP3A4 into pyrrolic esters that alkylate proteins and DNA and produce hepatic sinusoidal obstruction syndrome. Every commercial extract is defined by the removal of those alkaloids, which makes the specification, not the botanical name, the product.
Where to get Butterbur
Find Butterbur on iHerb →The evidence for Butterbur
Graded by what exists behind each claim.
✅ Clinically validated
- Petasin and isopetasin, the active sesquiterpene esters, reduce calcitonin gene-related peptide release from trigeminal afferents in a way consistent with inhibition of TRPA1 and TRPV1 channels — a mechanism in the same pathway the modern anti-CGRP migraine drugs target.
- A leaf extract standardized as Ze 339 has been trialed for allergic rhinitis with reported efficacy and safety, which is a separate indication from the rhizome extracts used for migraine.
- Case series of hepatobiliary events during migraine therapy with a Petasites hybridus extract are documented in the clinical literature and are the reason the regulatory position changed.
📊 Correlative data
- The plant is invasive enough in European waterways that its pyrrolizidine alkaloids have been measured contaminating stream and groundwater — an environmental finding, and a blunt reminder that the toxin is not a manufacturing artifact but the plant itself.
🧪 Theoretical / extrapolated benefits
- Calcium-channel blockade and leukotriene inhibition are both proposed as additional contributions to the anti-migraine and anti-allergic effects. They are mechanistically plausible and neither is established as the operative one in people.
How to read these tiers: they say how much human evidence exists, not how well something works — and ✗ flags harm, never a disappointing trial. How the evidence tiers work →
What Butterbur actually does
The actives are petasin and isopetasin, sesquiterpene esters of petasol, and their target is a pathway modern migraine drugs attack from the other end. In trigeminal afferent preparations both reduce evoked calcitonin gene-related peptide release, with pharmacology pointing at inhibition of TRPA1 and TRPV1 channels on those neurons Kleeberg-Hartmann 2021. CGRP release from trigeminal terminals is the event the monoclonal antibodies and gepants were designed to prevent; this is a plant doing something in the same pathway, at a different point, with far less precision.
Two further mechanisms are proposed and neither is established. Calcium-channel blockade in vascular smooth muscle is the older explanation, and inhibition of leukotriene synthesis is the more plausible route for the antiallergic effect of the leaf extracts Borlak 2022 Merk 2025. The rhizome extracts used for migraine and the leaf extracts used for rhinitis are different preparations with different constituent profiles, and conflating them is a common error.
Sitting in the same plant is the reason this page exists. Petasites hybridus contains pyrrolizidine alkaloids — senecionine and its relatives — which are not contaminants but constituents. They are not themselves toxic. Hepatic CYP3A4 oxidizes them to dehydro-pyrrolizidine esters, which are electrophilic pyrrolic alkylating agents that bind proteins and DNA in the sinusoidal endothelium. The result is hepatic sinusoidal obstruction syndrome, and the alkaloids are also genotoxic Seremet 2018.
So the pharmacology is bioactivation in the liver of a molecule that is inert until the liver acts on it, which is why the toxicity is dose-cumulative rather than acute, why it targets the liver specifically, and why the commercial answer is removal at manufacture rather than a dose limit at the label.
That the alkaloids belong to the plant and not to the process is demonstrable outside pharmacology entirely. Where butterbur has become invasive along European waterways, its pyrrolizidine alkaloids have been measured contaminating stream and seepage water in groundwater wells Kisielius 2020.
Cell, rodent, human — and where it stops
In neurons. Petasin and isopetasin reduce CGRP release from trigeminal afferents, with the channel pharmacology characterized Kleeberg-Hartmann 2021. That is a mechanistic result in a preparation, at concentrations chosen by the experimenter.
In invertebrate toxicology models, plant extracts containing pyrrolizidine alkaloids show measurable toxicity, which is how comparative screening of PA-containing preparations is done Seremet 2018.
In people, on the allergic indication. The leaf extract Ze 339 has been trialed for allergic rhinitis with reported efficacy and safety Merk 2025. This is a distinct product from the rhizome extracts and its evidence does not transfer to migraine, or its safety record to them.
In people, on the migraine indication, and this is where the chain breaks in an unusual place. The clinical case for Petasites in migraine prophylaxis has been reviewed with its mode of action, pharmacology and safety together Borlak 2022 — and the obstacle to transfer is not the trials. It is that hepatobiliary adverse events during migraine therapy with a Petasites hybridus extract were documented Anderson 2019, and the leading branded product was withdrawn in Germany. The efficacy question and the availability question came apart.
What that leaves a reader with is specific. The trials that supported this were run on one manufacturer's controlled, PA-depleted extract. What is on a shelf today is a different manufacturer's extract, and the evidence transfers only as far as the specification does.
Butterbur — which form, and does it matter
On this page the certificate of analysis is the product, and that is not a figure of speech. Every commercial butterbur extract is defined by what has been taken out. A supercritical carbon dioxide extraction leaves pyrrolizidine alkaloids behind because they are polar and CO2 is not; an ethanolic extract carries them across unless a separate removal step is performed.
An extract that states no pyrrolizidine alkaloid limit is not a gentler product than one that does. It is an unmeasured one. European regulators set daily PA exposure limits in the low micrograms for herbal products; a specification stating parts per billion is a claim somebody has tested, and its absence is not neutral information Kisielius 2020 Seremet 2018.
Rhizome and leaf are different products. The migraine literature is on root and rhizome extracts standardized to petasin and isopetasin, typically 7.5 mg per 50 mg capsule. The antiallergic literature is on the leaf extract Ze 339 Merk 2025. Buying one for the other's indication is buying a different plant part.
Exposure arithmetic. The migraine trials ran 50 to 75 mg of standardized extract twice daily for three to four months, so total exposure across a course is on the order of 9 to 18 g of extract. Pyrrolizidine toxicity is cumulative and idiosyncratic in onset rather than dose-threshold in the ordinary sense Anderson 2019, which is why the relevant number is the total taken over months and not the capsule.
A home tea or tincture of the raw plant is the unpurified form, and the unpurified form is the toxic one. There is no domestic process that removes pyrrolizidine alkaloids.
What would have to be true, and how you would know it was not
The efficacy prediction is a headache diary, and it needs a baseline written down before the first capsule. Migraine days per month, counted for 4 weeks before starting and for 12 weeks after. Prophylaxis in this literature is judged at three months Borlak 2022; a fortnight tells nobody anything, and migraine frequency regresses to the mean so strongly that starting after a bad month guarantees an apparent improvement.
The safety prediction is the one that must not be skipped. ALT and AST before starting, at 6 weeks and at 12 weeks. If the PA-depletion claim on a given product is correct, these should not move. A rise with no other explanation is the prediction that this product failed its specification, and it is the reason the branded extract was withdrawn Anderson 2019. Bilirubin belongs on the same panel.
The prediction that cuts against the herb. If the CGRP mechanism Kleeberg-Hartmann 2021 is the operative one, butterbur should add little on top of a CGRP monoclonal antibody, because the pathway is already blocked downstream. Anyone stacking the two and reporting a large additional benefit is describing something the stated mechanism does not predict.
What nobody has tested yet
Nobody knows whether a fully PA-free butterbur extract retains the clinical effect. That is the central open question and it is answerable: the migraine evidence was generated on extracts made before the strictest depletion standards, and no trial has compared a modern ultra-low-PA preparation against the historical one on migraine days. Until that is done, nobody can say whether current products are safer versions of what worked or merely safer.
The idiosyncratic component of the liver injury is uncharacterized. Hepatobiliary events occurred in people taking a controlled extract Anderson 2019, which means either the depletion failed in specific batches or something other than the alkaloids was responsible. Nobody has separated those two possibilities, and they have opposite implications for whether liver monitoring is sufficient.
And the leaf extract's safety record has not been formally transferred to the rhizome products. Ze 339 has its own trial base Merk 2025; whether its manufacturing controls are representative of the category is unknown, and the category is bought as one thing.
Butterbur — its own safety story, not its category's
This is the one page in this batch where the safety section is the reason the page exists.
Pyrrolizidine alkaloids are hepatotoxic and genotoxic after CYP3A4 bioactivation, and they cause hepatic sinusoidal obstruction syndrome Seremet 2018. They are plant constituents, not contaminants — the same alkaloids have been measured leaching from invasive stands of the plant into groundwater Kisielius 2020. Everything about the commercial product is an attempt to remove them.
Hepatobiliary adverse events during migraine therapy with a Petasites hybridus extract are documented, and the leading branded extract was withdrawn from the German market Anderson 2019. That is not a theoretical risk carried forward from the raw plant; it is what happened with the purified product.
Anyone using it should have liver enzymes checked before and during, and should stop immediately for jaundice, dark urine, right upper quadrant pain, nausea or unexplained fatigue. Do not combine it with other hepatotoxic drugs, with meaningful alcohol intake, or with anything else that loads CYP3A4.
Do not use in pregnancy, in breastfeeding, or in children. Pyrrolizidine alkaloids cross the placenta and appear in breast milk.
Butterbur is an Asteraceae plant. Cross-reactive allergy with ragweed, chrysanthemum, marigold and daisy is real and is the common non-hepatic adverse effect, alongside belching, which is the characteristic complaint with the oil-based softgels.
Never use a home preparation. Tea, tincture and dried herb are the forms with no depletion step at all.
Sources read for this page
- Borlak J. Petasites for Migraine Prevention: New Data on Mode of Action, Pharmacology and Safety. A Narrative Review. Front Neurol 2022 · PMID 35585841
- Kleeberg-Hartmann J. Petasin and isopetasin reduce CGRP release from trigeminal afferents indicating an inhibitory effect on TRPA1 and TRPV1 receptor channels. J Headache Pain 2021 · PMID 33849430
- Anderson N. Hepatobiliary Events in Migraine Therapy with Herbs: The Case of Petadolex, A Petasites Hybridus Extract. J Clin Med 2019 · PMID 31083451
- Kisielius V. The invasive butterbur contaminates stream and seepage water in groundwater wells with toxic pyrrolizidine alkaloids. Sci Rep 2020 · PMID 33188248
- Merk VM. Efficacy and Safety of P. hybridus Leaf Extract Ze 339 for the Treatment of Allergic Rhinitis. Adv Respir Med 2025 · PMID 40558112
- Seremet OC. Toxicity of plant extracts containing pyrrolizidine alkaloids using alternative invertebrate models. Mol Med Rep 2018 · PMID 29620235
How you would know if it worked
The markers here are not efficacy markers, and saying so is the point. Butterbur's constraint is hepatic: pyrrolizidine alkaloids are bioactivated in the liver, hepatobiliary events are what got the leading branded extract withdrawn in Germany, and the transaminases and GGT are what decide whether a course continues. Efficacy is counted in migraine days on a calendar; these decide whether you get to keep counting.
- Comprehensive Metabolic Panel (CMP) Retest: Every 3–6 months on any oral compound; annually otherwise.
- GGT (Gamma-Glutamyl Transferase) Retest: 6 weeks minimum after any change, because of the 2–3 week half-life. Sooner than that and you are measuring the previous month. Every 6–12 months as routine if you drink, carry visceral fat, or run oral compounds.
Draw before you start, not after. A result with nothing to compare it to answers nothing.
Butterbur — safety & side effects
- Pyrrolizidine alkaloids are hepatotoxic and cause veno-occlusive disease of the liver. The whole commercial category exists to remove them, and the removal is a manufacturing claim you are trusting.
- Hepatobiliary adverse events led to the withdrawal of the leading branded extract in Germany. Anyone taking this should have liver enzymes checked before and during use, and should stop immediately for jaundice, dark urine, right upper quadrant pain or unexplained fatigue.
- Do not use in pregnancy, breastfeeding or in children, and not alongside other hepatotoxic drugs or meaningful alcohol intake.
- Butterbur is an Asteraceae plant. Cross-reactivity with ragweed, chrysanthemum, marigold and daisy allergy is real.
- Never use a home preparation, tea or tincture of the raw plant. Those are the unpurified form, and the unpurified form is the toxic one.
Not medical advice. If you take prescription medication or have a diagnosed condition, check this against it with a pharmacist or doctor — pharmacists are underused and free.
- When to take it, and what to take it with
- Which form actually absorbs
- Who it's worth it for
- Coach Cam's stacks and notes
- Fasted or with food, and when in the day
- Morning or night, and why that window
- Around training, or deliberately away from it
- What it must not share a window with
Everything above is free and stays free. Skool is where it becomes a plan — Butterbur in an order, with the rest of what you're running.
Unlock in Skool — $10/mo →Bloodwork to run alongside Butterbur
Baseline first, then again at 8–12 weeks.
| Marker | What it’s watching for |
|---|---|
| TSH (Thyroid-Stimulating Hormone) | Thyroid disease imitates every cognitive complaint there is |
| Vitamin B12 | Deficiency causes fog long before it causes anemia |
| Methylmalonic Acid (MMA) | Catches the deficiency a normal B12 hides |
| Ferritin | Low iron flattens cognition at levels most labs call fine |
| Vitamin D (25-Hydroxy) | Commonly low, cheap to correct, associated with mood |
The Brain Fog & Cognition panel covers these in one order — 12 markers, $233.06 with the discount applied.
Check results you already have → · All 103 markers A–Z
Butterbur — frequently asked questions
What is Butterbur?
A migraine-prophylaxis herb whose defining fact is not its efficacy data but its chemistry. The raw plant contains hepatotoxic pyrrolizidine alkaloids, the commercial extracts are defined by having those removed, and the best-known branded product was withdrawn in Germany after hepatobiliary adverse events. Everything about buying this comes down to whether the removal was done and documented.
What is the suggested dose of Butterbur?
The migraine literature used 50–75 mg of standardized rhizome extract twice daily. Nothing here should be run without knowing the pyrrolizidine alkaloid specification. This is a general reference for education only — statements have not been evaluated by the FDA and this is not medical advice.
Where can I find Butterbur dosing and the full breakdown?
The suggested dose and the full evidence — clinical, correlative and theoretical — are on this page. What's inside Skool is when to take it, which form actually absorbs, the brand worth buying and Coach Cam's stacks.
Where can I buy Butterbur?
Coach Cam sources Butterbur from vetted, top-rated brands on iHerb — use the buy link on this page.
What Butterbur is used for
Butterbur appears under 1 goal in the goal router.
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Where this goes next
The pages here are the frameworks. The protocols — the dosing, the order to correct things in, the week-by-week schedule and what to retest — are inside Skool.