Phytotherapy · Migraine & Allergy Research · Asteraceae

Butterbur

Petasites hybridus (L.) Gaertn. (Asteraceae) — a plant of European stream banks whose rhizome extract, stripped of its toxic pyrrolizidine alkaloids, is studied for migraine prevention and allergic rhinitis. Its petasins are the active compounds, and the unprocessed plant is a genuine liver hazard.

15 Primary Refs
12 Properties
Rhizome Parts Used
✦ Researched
Last Updated October 30, 2026
Primary Source Wikiphyto · NCBI PubMed · LiverTox
Family Asteraceae
Wetland Herb · Giant-Leaved

Botanical Overview

At flowering, butterbur stands 20 to 50 cm tall, with brown-bracted flower heads and reddish tubular flowers that smell faintly of vanilla. After flowering it grows to about 1 m, with very large heart-shaped basal leaves, toothed, hairy underneath, on a foul-smelling stalk. It grows on stream banks and in wet, marshy ground.

Flowering Height20–50 cm
Basal LeavesHeart-shaped, up to 1 m wide
FlowersReddish, vanilla-scented
HabitatStream banks, wet ground
Taxonomic Classification

Taxonomy & Identification

Latin Name
Petasites hybridus (L.) Gaertn. (synonyms Petasites officinalis Moench and Petasites vulgaris L.)
Family
Asteraceae
Common Names
Butterbur, Pétasite
Parts Used
Rhizome, preferably fresh
Regulatory Status
French Pharmacopoeia, list B
Ethnobotany & Traditional Use

History & Tradition

The genus name comes from the Greek petasos, a broad-brimmed felt hat, for the plant's huge leaves. Those leaves were used to wrap butter, which gave butterbur its English name.

European herbalists relied on it for centuries: in the Middle Ages against plague and fever, and in the 17th century for cough, asthma and skin wounds. Its traditional uses rest mainly on its antispasmodic action.

Modern research turned to a standardized root extract, with placebo-controlled trials in migraine prevention and a head-to-head trial in hay fever. 5239

⚠ Alkaloid-Free Extracts Only

The raw plant contains liver-toxic pyrrolizidine alkaloids. Only extracts processed to remove them are appropriate for use. 15

Timeline

The Hat Plant

Etymology

Named from the Greek petasos, a wide felt hat, for its giant leaves.

Plague & Fever Remedy

Middle Ages

Used in Europe against plague and fever.

Cough, Asthma & Wounds

17th Century

Prescribed for cough, asthma and skin wounds.

Migraine Trials & Safety Review

2000 – 2022

Migraine trials, TRPA1 findings and a safety review of the extract. 7

The Key Compounds

Petasins & Isopetasin — Deep Dive

The eremophilane sesquiterpene esters behind butterbur's activity, and the alkaloids that must be removed.

🧪

Petasine & Neopetasine

Angelic-acid esters of petasol. Petasin is the best-known compound of the root, and the extract is standardized to it. 1

🎯

Isopetasin

The antimigraine component of butterbur. It activates TRPA1 channels on pain-sensing nerves and then desensitizes them. 6

🧬

S-Petasines

The S-methylacrylic acid esters: S-petasine, neo-S-petasine and iso-S-petasine, alongside fukinone and bakkenolide.

☠️

Pyrrolizidine Alkaloids

Senecionine, integerrimine and senkirkine occur in traces, but they are hepatotoxic and genotoxic, and are removed from medicinal extracts. 15

Pharmaceutical Preparations

Parts Used & Available Forms

The rhizome is used, and only as a standardized extract free of pyrrolizidine alkaloids.

Rhizome

The underground stem, preferably fresh; root extracts are favored.

Rhizome

Standardized Extract

Rhizome extract standardized to petasin and isopetasin, with the pyrrolizidine alkaloids removed.

Standardized Extract

PA-Free Extract

Extracts must contain less than 1 microgram of pyrrolizidine alkaloids per daily dose.

Alkaloid-Free

Mother Tincture

Teinture-mère of the whole plant, for which root extracts are preferred.

Liquid Extract

Clinical Dosimetry

Dosages

Butterbur is taken as an alkaloid-free standardized extract, twice a day with meals.

Form Dose Frequency Context Notes
Standardized Rhizome Extract 50–100 mg (7.5–15 mg petasin) Twice daily, with meals General use Pyrrolizidine alkaloids must stay below 1 microgram per daily dose.
Alkaloid-Free Root Extract 50–75 mg Twice daily, with meals Migraine prevention Taken for 4 to 6 months. 235
Phytochemistry

Composition

Sesquiterpene esters carry the pharmacology, and traces of toxic alkaloids set the safety limits.

Rhizome — Sesquiterpenes

Sesquiterpene Alcohol EstersEsters of petasol, isopetasol and neopetasol (eremophilane type)
Major
Angelic-Acid EstersPetasine, neopetasine and isopetasine 16
Present
S-Methylacrylic EstersNeo-S-petasine, S-petasine and iso-S-petasine
Present
Other EstersEsters of 3-methylcrotonic, methacrylic and isobutyric acids
Present
LactonesFukinone and bakkenolide (fukinanolide)
Present

Other Constituents

Essential OilDodecanal, which gives the plant its odor
Present
FlavonoidsIsoquercitroside, astragaloside and quercetol
Present
MucilagesPresent in the rhizome
Present
TanninsPresent in the rhizome
Present
Pyrrolizidine AlkaloidsTraces of senecionine, integerrimine and senkirkine; hepatotoxic 15
Toxic

Plant Properties — Pharmacodynamics

Twelve pharmacodynamic properties define butterbur, centered on pain pathways, leukotrienes and one serious safety hazard.

12 Properties Antimigraine Antiallergic Clinical Trials
💥

Antispasmodic

Relaxes smooth muscle, and the effect is stronger than that of papaverine.

🔥

Anti-Inflammatory

Probably inhibits leukotriene synthesis and both COX-1 and COX-2. 1

🧠

Antimigraine

A special root extract at 50 to 75 mg twice daily reduced migraine in trials. 235

🎯

Nociceptor Desensitization

Isopetasin activates TRPA1 on peptidergic nociceptors and then desensitizes them. 6

⚡

CGRP & Enzyme Inhibition

The extract blocks cyclooxygenases, lipoxygenases and phospholipase A2, acts on TRPA1 and TRPV1, and lowers CGRP release from meningeal nerves. 7

🫃

Gastroprotective

Inhibits vasoconstrictive leukotrienes without affecting cyclooxygenase; isopetasin shows this activity and petasin does not. 8

🤧

Antiallergic

Petasins block leukotriene synthesis by leukocytes. 91014

🫁

Mucolytic

Helps loosen bronchial secretions in cough and hoarseness.

💧

Diuretic & Sudorific

Increases urine output and sweating.

😌

Analgesic & Sedative

Soothes pain and tension in functional neurodystonia.

🧒

Pediatric Migraine Prevention

An open study with a special root extract covered children and adolescents. 4

☠️

Alkaloid Hepatotoxicity

Pyrrolizidine alkaloids damage the liver and act through genotoxic mechanisms. 15

Clinical Applications

Clinical Indications

Butterbur extract is studied mainly for migraine prevention and allergic rhinitis, with a long traditional use for spasms.

🧠
Migraine Prevention
Primary Indication
  • Adults: placebo-controlled trials of a special root extract at 50 to 75 mg twice daily. 235
  • Children & Adolescents: reported in an open study with a special root extract. 4
  • Reviews: a systematic review, a review of phytomedicines in migraine and a 2012 American Academy of Neurology guideline (since retired) covered butterbur. 111213
🤧
Allergic Rhinitis
Clinical Indication
  • Versus Cetirizine: a randomized trial in seasonal allergic rhinitis. 9
  • Anti-Inflammatory Activity: an extract showed activity in allergic rhinitis, and petasins were studied in allergic disease. 1014
  • Respiratory Tradition: cough, hoarseness and bronchial asthma.
💥
Smooth Muscle Spasm
Traditional Indication
  • Urinary Tract: spasms with kidney or bladder stones.
  • Digestive Tract: gastrointestinal spasms.
  • Dysmenorrhea: painful periods.
🩹
Skin & Wounds
Traditional Indication
  • Topical Use: a traditional remedy for wounds and skin disorders.
  • Safety: unprocessed plant material carries the alkaloid hazard.
Pharmacodynamics

Mode of Action

Butterbur's petasins act on pain-sensing nerves and on leukotriene pathways.

🎯

TRPA1 Activation & Desensitization

Isopetasin activates TRPA1 channels, which first excites neuropeptide-containing nociceptors and is then followed by their desensitization. 6

🧠

CGRP Release & Pain Enzymes

The extract inhibits cyclooxygenases, lipoxygenases and phospholipase A2, acts on TRPA1 and TRPV1, and reduces CGRP release from meningeal afferents during attacks. 7

🤧

Leukotriene Synthesis in Allergy

Petasins inhibit the synthesis of leukotrienes by leukocytes, which underlies the antiallergic effect. 91014

🫃

Peptido-Leukotriene Inhibition in the Gut

Isopetasin inhibits vasoconstrictive leukotrienes without touching cyclooxygenase, giving the gastroprotective effect. 8

🔥

Petasin & Inflammation

Petasin takes part in the anti-inflammatory activity of the extract, probably through leukotriene and COX inhibition. 1

Clinical Safety

Safety & Interactions

Unprocessed butterbur can injure the liver, so only alkaloid-free extracts are used, and never in pregnancy.

⚠ Genuine, Serious Risks: Liver Toxicity

Read Before Using Any Butterbur Product

  • Pyrrolizidine alkaloids: senecionine, integerrimine and senkirkine are hepatotoxic, and their carcinogenic potential is attributed to genotoxic mechanisms. 15
  • Liver injury: hepatocellular injury with jaundice appeared 2 to 12 weeks after starting butterbur products, and 2 of the cases in one review needed urgent liver transplants. 15
  • Withdrawals: several products were withdrawn in Switzerland and Germany after these reports. 15
  • What to do: stop butterbur and have liver tests if fatigue, nausea, abdominal pain or dark urine appear. Alkaloid-free preparations do not appear to cause liver injury, but processing is critical to their safety. 15
⚠️

Adverse Effects & Precautions

  • Liver Injury: reported with alkaloid-containing products. 15
  • Carcinogenic Potential: linked to the genotoxic alkaloids of the raw plant.
  • Whole-Plant Products: tinctures and teas of the unprocessed plant carry the alkaloid hazard.
  • Monitoring: liver tests are advised if symptoms of liver trouble appear.
🚫

Contraindications & Interactions

  • Pregnancy & Lactation: avoid.
  • Liver Disease: avoid in anyone with a history of hepatitis or liver disease.
  • Alkaloid Limit: less than 1 microgram of pyrrolizidine alkaloids per daily dose.
  • Regulatory Status: French Pharmacopoeia, list B.
Clinical Disclaimer: This information is for educational purposes only and is not a substitute for professional medical advice. Consult a qualified healthcare provider before using butterbur, particularly if you have liver disease, are pregnant or breastfeeding, take medicines that affect the liver, or are allergic to Asteraceae plants.
Common Questions

Frequently Asked Questions

What is butterbur used for?
Butterbur (Petasites hybridus) rhizome extract is used for migraine prevention and for allergic rhinitis. Traditionally the plant has also been used for cough, asthma, urinary tract spasms, digestive spasms, painful periods and skin wounds.
Does butterbur prevent migraines?
A special root extract reduced migraine frequency in placebo-controlled trials, and an open study reported the same in children and adolescents. The 2012 American Academy of Neurology guideline covered butterbur among complementary treatments for episodic migraine prevention, and that guideline has since been retired.
Is butterbur safe for the liver?
Only extracts with the pyrrolizidine alkaloids removed should ever be used. These alkaloids are toxic to the liver and are linked to genotoxic effects. Cases of liver injury, some needing a liver transplant, were reported with butterbur products, and several products were withdrawn in Switzerland and Germany.
What is the usual butterbur dosage?
The usual dose is 50 to 100 mg of extract (7.5 to 15 mg of petasin) twice a day with meals. For migraine prevention, 50 to 75 mg of alkaloid-free standardized extract is taken twice daily with meals for 4 to 6 months. A daily dose should contain less than 1 microgram of pyrrolizidine alkaloids.
Does butterbur help with allergies?
A randomized trial compared butterbur with cetirizine in seasonal allergic rhinitis, and another study found anti-inflammatory activity of an extract in allergic rhinitis. Petasins inhibit the synthesis of leukotrienes by leukocytes, which is the proposed explanation.
What is petasin?
Petasin is the best-known sesquiterpene ester of butterbur, an angelic-acid ester of petasol. Together with isopetasin and neopetasin it forms the petasins, which carry the anti-inflammatory and antimigraine activity.
Can children take butterbur?
An open study with a special root extract reported on migraine prevention in children and adolescents. Because of the liver concerns, any use in children belongs under medical supervision.
Is butterbur safe in pregnancy?
No. Butterbur should be avoided during pregnancy and breastfeeding, and by anyone with a history of hepatitis or liver disease.
What does a PA-free butterbur extract mean?
It is a rhizome extract processed to remove the pyrrolizidine alkaloids, to under 1 microgram per daily dose. Preparations processed this way do not appear to cause liver injury, but processing is critical to safety, and liver tests are advised if fatigue, nausea, abdominal pain or dark urine appear.
Sources

Bibliography

↑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. Biochem Pharmacol. 2001.
PubMed: PMID 11286996 →
↑2. 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.
Abstract →
↑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. Eur Neurol. 2004.
PubMed: PMID 14752215 →
↑4. Pothmann R, Danesch U. Migraine prevention in children and adolescents: results of an open study with a special butterbur root extract. Headache. 2005.
PubMed: PMID 15836592 →
↑5. Grossmann M, Schmidramsl H. An extract of Petasites hybridus is effective in the prophylaxis of migraine. Int J Clin Pharmacol Ther. 2000.
PubMed: PMID 11020030 →
↑6. Benemei S, De Logu F, Li Puma S, et al. The anti-migraine component of butterbur extracts, isopetasin, desensitizes peptidergic nociceptors by acting on TRPA1 cation channel. Br J Pharmacol. 2017.
PubMed: PMID 28622417 →
↑7. 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. Front Neurol. 2022.
PubMed: PMID 35585841 →
↑8. Brune K, Bickel D, Peskar BA. Gastro-protective effects by extracts of Petasites hybridus: the role of inhibition of peptido-leukotriene synthesis. Planta Med. 1993.
PubMed: PMID 8302945 →
↑9. Schapowal A. Randomised controlled trial of butterbur and cetirizine for treating seasonal allergic rhinitis. BMJ. 2002;324(7330):144–146.
Full Text →
↑10. Thomet OA, Simon HU. Petasins in the treatment of allergic diseases: results of preclinical and clinical studies. Int Arch Allergy Immunol. 2002.
PubMed: PMID 12403927 →
↑11. 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.
PubMed: PMID 22529203 →
↑12. Agosti R, Duke RK, Chrubasik JE, Chrubasik S. Effectiveness of Petasites hybridus preparations in the prophylaxis of migraine: a systematic review. Phytomedicine. 2006.
PubMed: PMID 16987643 →
↑13. Rajapakse T, Davenport WJ. Phytomedicines in the treatment of migraine. CNS Drugs. 2019.
PubMed: PMID 30627973 →
↑14. Thomet OA, Schapowal A, Heinisch IV, Wiesmann UN, Simon HU. Anti-inflammatory activity of an extract of Petasites hybridus in allergic rhinitis. Int Immunopharmacol. 2002.
PubMed: PMID 12188041 →
↑15. LiverTox: Clinical and Research Information on Drug-Induced Liver Injury. Butterbur. Bethesda (MD): National Institute of Diabetes and Digestive and Kidney Diseases; 2012–. Updated 18 February 2019.
Full Text →

Additional Sources

Wichtl M, Anton R. Plantes thérapeutiques: Tradition, pratique officinale, science et thérapeutique. Cachan: Éditions Tec & Doc; 1999. p. 403.
Passeport Santé.
passeportsante.net →