Butterbur Benefits

Butterbur (Petasites hybridus, family Asteraceae) is the most awkward herb on this website, and it is worth understanding exactly why. Most herbal remedies fail on the evidence: the trials are tiny, unblinded, or absent. Butterbur is the opposite. It has genuine randomised, placebo-controlled trials for two common conditions — migraine prevention and allergic rhinitis — and for a few years it held the highest possible efficacy rating from a mainstream neurology guideline. Then the rating was pulled. Not because a new trial failed, but because the raw plant contains pyrrolizidine alkaloids that poison the liver and cause cancer, and nobody could be confident that the products on the shelf were reliably free of them.

These four articles hold both halves of that story at once. If you want the short version: the efficacy data are real, the safety problem is real, and the only version of this herb that anyone should even discuss is a certified pyrrolizidine-alkaloid-free, standardised extract — never the raw root, never a leaf tea, never a home tincture, never in pregnancy or breastfeeding, and not for children.

Table of Contents

1. Deep-Dive Articles
2. What “Butterbur” Means in a Trial
3. The Evidence Map
4. Petasin and Isopetasin: One Mechanism, Two Uses
5. The Level A Rating and Its Withdrawal
6. The Red Lines
7. Key Research Papers
8. External Resources
9. Connections

Deep-Dive Articles

Four articles, in the order that makes sense to read them. The first two are what butterbur can do. The second two are what butterbur can do to you, and how to tell whether a product is even worth considering. Please do not read the first pair without the second.

What “Butterbur” Means in a Trial

This distinction decides whether any research on this page applies to a bottle in your hand, so it comes first.

Butterbur is a large-leaved perennial of wet ground — riverbanks, ditches, damp meadows — across Europe and western Asia. The leaves are enormous, and before refrigeration they were used to wrap butter, which is where the name comes from. Herbalists once called it “pestilence wort” and used it for plague, fever, cough and spasm. None of that folklore is what modern research is about. Traditional use is history, not evidence.

Every positive trial cited across these four articles used a manufactured, standardised root or rhizome extract in which the pyrrolizidine alkaloids had been deliberately stripped out and the active sesquiterpenes concentrated and measured. Two named preparations account for essentially the entire literature:

• Petadolex — a carbon-dioxide extract of the rhizome, standardised to petasins, used in the migraine trials at 50 mg or 75 mg twice daily.
• Ze 339 (Tesalin) — a different standardised extract developed for allergic rhinitis, dosed as tablets standardised to their petasine content and taken three or four times a day during the pollen season.

A bag of dried butterbur root, a wildcrafted leaf tea, a homemade tincture, or a capsule that says only “butterbur extract” with no alkaloid testing and no petasin figure is not the same substance. It has never been tested for efficacy and it has an unknown alkaloid load. There is no safe way to prepare the raw plant at home, and no amount of careful brewing removes pyrrolizidine alkaloids.

The Evidence Map

An honest summary of where butterbur stands, use by use.

Petasin and Isopetasin: One Mechanism, Two Uses

It is fair to ask why one plant would help both a headache disorder and hay fever. The answer is that the two active compounds have two separate actions, one of which fits each condition.

The molecules credited with butterbur’s effects are sesquiterpene esters — chiefly petasin and its isomer isopetasin, along with oxopetasin. A good extract is labelled by its petasin content, which is why “standardised to petasins” is a meaningful phrase and “10:1 extract” is not. Two mechanisms have laboratory support:

1. Inhibition of leukotriene synthesis. Leukotrienes are inflammatory messengers that drive the swelling, mucus and congestion of an allergic reaction — the same pathway targeted by drugs such as montelukast. Laboratory work on human inflammatory cells found that petasin accounted for much of a butterbur extract’s ability to suppress leukotriene production. This is the plausible route to the hay-fever effect.
2. Calcium-channel blockade. S-petasin inhibited L-type calcium current in a neuronal cell line — the same class of channel that prescription calcium-channel blockers act on. Restricting calcium entry relaxes vascular and smooth muscle and dampens neuronal excitability, which is a credible, though unproven, route to migraine prevention.

Both findings are cell-culture work, and the calcium-channel study used a compound from a related species, Petasites formosanus, in a neuroblastoma–glioma hybrid line. A mechanism that works in a dish is a hypothesis, not a result. The reason anyone considers butterbur at all is the clinical trials, not the pharmacology.

One further point of chemistry matters for safety: petasins and pyrrolizidine alkaloids are entirely different molecules. The petasins are the useful ones. The alkaloids are the dangerous ones. The entire purpose of the manufacturing process is to keep the first group and remove the second — which means the quality of the manufacturing is the safety of the product.

The Level A Rating and Its Withdrawal

In 2012 the American Academy of Neurology and the American Headache Society published a guideline on non-drug and complementary treatments for episodic migraine prevention. Petasites was rated Level A — established as effective. It was the only botanical to reach the top tier, sitting alongside several prescription drugs.

That rating no longer stands. The published guideline now carries a [RETIRED] label, and in 2015 the Academy moved to make clinicians and patients aware of the hepatotoxicity concern surrounding butterbur products. The accurate way to describe what happened is this:

• The efficacy evidence did not change. No new trial overturned the earlier results.
• What changed was the weight given to liver safety and product-quality uncertainty — reports of liver injury in people taking commercial butterbur, regulatory action abroad, and the fact that in the United States nobody verifies before sale that a given bottle is actually alkaloid-free.
• A guideline that says “this works” is useless if it cannot also say “and this specific bottle is safe.” That is the gap that retired the recommendation.

This is not a story about herbal medicine being dismissed. It is a story about a herb that earned a mainstream endorsement on merit and then lost it on manufacturing. Both halves are true, and you deserve to hear both before deciding anything.

The Red Lines

These apply across all four articles and are not negotiable.

• Never the raw herb. No wild-harvested root or leaf, no homemade tea, no homemade tincture, no bulk powder of unknown origin. Raw butterbur contains hepatotoxic and carcinogenic pyrrolizidine alkaloids.
• Never in pregnancy or breastfeeding. Pyrrolizidine alkaloids cross the placenta and enter breast milk, and infant liver injury from PA-containing herbal tea has been documented.
• Not for children. The paediatric efficacy data are weak, and a growing liver has the most to lose.
• Not with liver disease, heavy alcohol use, or alongside other medicines and supplements that stress the liver.
• Caution with Asteraceae allergy. Butterbur is in the same botanical family as ragweed, chrysanthemum, marigold, daisy, chamomile, echinacea and feverfew. Cross-reactive allergic responses are possible — and ragweed allergy is exactly what sends people looking for hay-fever remedies in the first place.
• Only a certified PA-free, standardised product, from a manufacturer that will produce a certificate of analysis, for a limited period, with liver enzymes checked before and during use. If you cannot verify the alkaloid testing, do not take it.
• Stop immediately and seek care for yellowing of the skin or eyes, dark urine, pale stools, persistent nausea, right-upper-abdominal pain or unexplained fatigue.

And a final, honest framing: for both of butterbur’s indications there are alternatives with comparable evidence and cleaner safety records — magnesium, riboflavin and coenzyme Q10 for migraine; intranasal corticosteroids, saline rinses and non-sedating antihistamines for hay fever. Butterbur is not a first choice for most people. It is a considered, supervised, second or third choice for someone who has already tried the safer options.

Key Research Papers

Every identifier below was checked live against the NCBI PubMed database before it was published here: title, first author, journal and year all had to match. Findings are labelled as human trial, laboratory or case report, and negative results are reported as negative.

Migraine prevention — the randomised trials

1. Lipton RB, Göbel H, Einhäupl KM, Wilks K, Mauskop A. Petasites hybridus root (butterbur) is an effective preventive treatment for migraine. Neurology. 2004;63(12):2240–2244. Human randomised trial, 245 participants; 75 mg twice daily reduced attack frequency about 48% versus 26% on placebo. The 50 mg dose did not separate convincingly from placebo.
2. Grossmann M, Schmidramsl H. An extract of Petasites hybridus is effective in the prophylaxis of migraine. International Journal of Clinical Pharmacology and Therapeutics. 2000;38(9):430–435. The first placebo-controlled trial, at 50 mg twice daily over 12 weeks.
3. Diener HC, Rahlfs VW, Danesch U. The first placebo-controlled trial of a special butterbur root extract for the prevention of migraine: reanalysis of efficacy criteria. European Neurology. 2004;51(2):89–97. A reanalysis of the same 2000 dataset using different endpoints — not an independent second trial.
4. Agosti R, Duke RK, Chrubasik JE, Chrubasik S. Effectiveness of Petasites hybridus preparations in the prophylaxis of migraine: a systematic review. Phytomedicine. 2006;13(9–10):743–746. Concluded the randomised evidence supported butterbur, while noting all of it used the same proprietary extract.

Guidelines, reviews and safety reassessment

1. Holland S, Silberstein SD, Freitag F, Dodick DW, Argoff C, Ashman E. Evidence-based guideline update: NSAIDs and other complementary treatments for episodic migraine prevention in adults. Neurology. 2012;78(17):1346–1353. The guideline that rated butterbur Level A — now carrying a [RETIRED] designation.
2. Sutherland A, Sweet BV. Butterbur: an alternative therapy for migraine prevention. American Journal of Health-System Pharmacy. 2010;67(9):705–711. A pharmacy review weighing efficacy against the alkaloid problem.
3. Borlak J, Diener HC, Kleeberg-Hartmann J, Messlinger K, Silberstein S. Petasites for migraine prevention: new data on mode of action, pharmacology and safety. A narrative review. Frontiers in Neurology. 2022;13:864689. A narrative review arguing the liver signal is weaker than assumed; read it alongside the regulatory actions, not instead of them.

Allergic rhinitis

1. Schapowal A. Randomised controlled trial of butterbur and cetirizine for treating seasonal allergic rhinitis. BMJ. 2002;324(7330):144–146. Human trial, 125 participants over two weeks; butterbur and cetirizine improved symptoms comparably, with less sedation and fatigue on butterbur. No placebo arm.
2. Schapowal A. Treating intermittent allergic rhinitis: a prospective, randomized, placebo and antihistamine-controlled study of butterbur extract Ze 339. Phytotherapy Research. 2005;19(6):530–537. Butterbur compared with fexofenadine and placebo.
3. Schapowal A. Butterbur Ze339 for the treatment of intermittent allergic rhinitis: dose-dependent efficacy in a prospective, randomized, double-blind, placebo-controlled study. Archives of Otolaryngology–Head & Neck Surgery. 2004;130(12):1381–1386. The dose-response study.
4. Guo R, Pittler MH, Ernst E. Herbal medicines for the treatment of allergic rhinitis: a systematic review. Annals of Allergy, Asthma & Immunology. 2007;99(6):483–495. An independent review placing butterbur among the better-supported herbal options while noting the narrow evidence base.

Pharmacology of petasin and isopetasin

1. Thomet OA, Wiesmann UN, Schapowal A, Bizer C, Simon HU. Role of petasin in the potential anti-inflammatory activity of a plant extract of Petasites hybridus. Biochemical Pharmacology. 2001;61(8):1041–1047. Laboratory work identifying petasin as the main anti-inflammatory constituent.
2. Thomet OA, Simon HU. Petasins in the treatment of allergic diseases: results of preclinical and clinical studies. International Archives of Allergy and Immunology. 2002;129(2):108–112.
3. Wu SN, Chen H, Lin YL. The mechanism of inhibitory actions of S-petasin, a sesquiterpene of Petasites formosanus, on L-type calcium current in NG108-15 neuronal cells. Planta Medica. 2003;69(2):118–124. Cell-culture study, and in a related species — the origin of the calcium-channel hypothesis.

Pyrrolizidine alkaloids and liver safety

1. Anderson N, Borlak J. Hepatobiliary events in migraine therapy with herbs — the case of Petadolex, a Petasites hybridus extract. Journal of Clinical Medicine. 2019;8(5). A detailed analysis of the reported liver events with the standardised migraine extract.
2. Edgar JA, Molyneux RJ, Colegate SM. Pyrrolizidine alkaloids: potential role in the etiology of cancers, pulmonary hypertension, congenital anomalies, and liver disease. Chemical Research in Toxicology. 2015;28(1):4–20.
3. Neuman MG, Cohen L, Opris M, Nanau RM, Hyunjin J. Hepatotoxicity of pyrrolizidine alkaloids. Journal of Pharmacy & Pharmaceutical Sciences. 2015;18(4):825–843.
4. Moreira R, Pereira DM, Valentão P, Andrade PB. Pyrrolizidine alkaloids: chemistry, pharmacology, toxicology and food safety. International Journal of Molecular Sciences. 2018;19(6).
5. Avula B, Wang YH, Wang M, Smillie TJ, Khan IA. Simultaneous determination of sesquiterpenes and pyrrolizidine alkaloids from the rhizomes of Petasites hybridus (L.) G.M. et Sch. and dietary supplements using UPLC-UV and HPLC-TOF-MS methods. Journal of Pharmaceutical and Biomedical Analysis. 2012;70:53–63. The analytical chemistry that makes an independent “PA-free” check possible at all.

Live PubMed Searches

1. Petasites hybridus
2. Butterbur migraine prophylaxis
3. Ze 339 allergic rhinitis
4. Petasin, isopetasin and leukotrienes
5. Pyrrolizidine alkaloid hepatotoxicity
6. Hepatic veno-occlusive disease
7. Petadolex and the liver
8. Asteraceae allergy cross-reactivity

External Resources

• LiverTox — the NIH database of drug- and herb-induced liver injury
• NCCIH — Butterbur at a Glance
• PubMed — the full Petasites hybridus literature
• PubChem — petasin compound record
• EFSA — pyrrolizidine alkaloids in food and supplements
• World Flora Online — Petasites hybridus taxonomy
• ClinicalTrials.gov — registered butterbur trials

Connections

• Butterbur — the main topic page
• Migraine Prevention
• Allergic Rhinitis and Hay Fever
• Pyrrolizidine Alkaloids and Liver Safety
• Choosing a PA-Free Product
• Feverfew — the other migraine herb, and an Asteraceae relative
• Comfrey — the other pyrrolizidine-alkaloid herb
• Stinging Nettle — a gentler hay-fever option
• Neurology
• Migraine
• Pain & Allergy
• Magnesium
• Vitamin B2 (Riboflavin)
• Quercetin
• Milk Thistle
• Liver Function Tests
• Histamine, Mast Cells & Allergy — interactive animation
• All Herbs

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