Butterbur

Metadata

Approved Indications

Commission E (Germany)

• Commission E originally approved Petasites for supportive therapy of acute spastic pain of the urinary tract and adjunctive treatment of migraine
• However, the product was subsequently withdrawn from the German market in 2009 due to hepatotoxicity concerns

ESCOP

• No current ESCOP monograph for migraine indication

EMA/HMPC

• The HMPC has not issued a positive monograph for Petasites
• Concerns over PA content and hepatotoxicity have prevented formal EU-level traditional use or well-established use classification

AAN (American Academy of Neurology)

• In 2012, the AAN evidence-based guideline update classified Petasites (butterbur) as Level A (established as effective) for migraine prevention based on two Class 1 RCTs
• This was the highest recommendation level given to any complementary treatment for migraine
• The AAN subsequently retired these guidelines citing safety concerns and the need for updated review
• The Level A recommendation is no longer active

Agreement/Disagreement Analysis

A remarkable case of regulatory reversal: butterbur went from Commission E approval and AAN Level A to market withdrawal and guideline retirement. The efficacy evidence has not been disputed — the issue is entirely about the safety signal from PA contamination and potential hepatotoxicity.

Conditions Treated

Migraine Prophylaxis (Primary Indication)

• Prevention of episodic migraine in adults
• Reduction of attack frequency, severity, and duration

Allergic Rhinitis (Secondary Indication)

• Several trials comparing butterbur to cetirizine (fexofenadine equivalent)
• ZE 339 extract (standardized for petasins) studied for hay fever
• Some evidence of comparable efficacy to second-generation antihistamines
• [NEEDS-RESEARCH] Less extensively studied than migraine indication

Historical Uses

• Spastic pain of urinary tract (original Commission E indication)
• Spasmodic cough (traditional)
• Pain and spasm of GI tract (traditional)

Mechanism of Action

Key Active Compounds

• Petasin and isopetasin: Sesquiterpene esters; primary active compounds
  • Petasin content in Petadolex: standardized to minimum 7.5 mg per 50 mg capsule
• Pyrrolizidine alkaloids (PAs): TOXIC components naturally present in the plant
  • Senecionine, integerrimine, senkirkine and related PAs
  • Must be removed during manufacturing (Petadolex is certified PA-free)

Migraine Prophylaxis Mechanism

• CGRP signaling blockade: Petasin blocks calcitonin gene-related peptide (CGRP) signaling — the same target as the new monoclonal antibody migraine drugs (erenumab, galcanezumab, etc.)
• Calcium channel modulation: Petasin modulates voltage-dependent calcium channels
• Spasmolytic activity: Relaxes vascular smooth muscle
• Anti-inflammatory: Inhibits leukotriene synthesis and COX-2 activity
• 5-HT receptor effects: Modulation of serotonin pathways

Allergic Rhinitis Mechanism

• Leukotriene inhibition (similar to montelukast mechanism)
• Histamine release inhibition
• Anti-inflammatory effects in nasal mucosa

Clinical Evidence Summary

Pivotal Migraine Trial 1 (Grossman & Schmidramsl, 2000)

• Design: Randomized, double-blind, placebo-controlled
• n = 60 migraine patients
• Petadolex 50 mg twice daily vs. placebo for 12 weeks
• Result: Migraine attack frequency decreased by up to 60% from baseline
• Reduction was statistically significant vs. placebo
• Published: Phytomedicine

Pivotal Migraine Trial 2 (Lipton et al., 2004)

• Design: Three-arm, parallel-group, randomized, double-blind, placebo-controlled
• n = 245 migraine patients
• Arms: Petadolex 75 mg BID (150 mg/day) vs. Petadolex 50 mg BID (100 mg/day) vs. placebo BID
• Duration: 4 months
• Primary outcome: Proportion with >=50% reduction in attack frequency
  • 150 mg/day: 68% (responder rate)
  • 100 mg/day: 56%
  • Placebo: 49%
• 150 mg dose was statistically significant vs. placebo
• AAN classified as Class 1 evidence
• Published: Neurology (2004) PMID: 15623680

AAN Guideline Classification (2012)

• Both trials evaluated as Class 1 evidence
• Level A recommendation: “Petasites (butterbur) is established as effective for migraine prevention (based on 2 Class I studies)”
• This was the only Level A herbal recommendation in the AAN migraine guidelines
• Guidelines subsequently retired (circa 2015-2016) due to safety concerns

Allergic Rhinitis Trials

• Schapowal (2002): RCT comparing butterbur (ZE 339, 4 tablets/day) vs. cetirizine 10 mg in seasonal allergic rhinitis
  • Non-inferior to cetirizine for symptom relief
  • Less sedating than cetirizine
• Additional comparative trials with fexofenadine
• [UNCERTAIN] Whether efficacy is comparable to second-generation antihistamines requires more data

The Safety Controversy

Pyrrolizidine Alkaloids (PAs)

• All Petasites species naturally contain PAs, which are hepatotoxic, genotoxic, and potentially carcinogenic
• PAs cause hepatic veno-occlusive disease (sinusoidal obstruction syndrome)
• Petadolex manufacturing process was designed to remove PAs to below detectable levels
• The product was certified as “PA-free” by independent testing

Hepatotoxicity Reports

• Regulatory agencies (BfArM in Germany, EMA) received reports of liver injury in patients taking butterbur products
• Reports included elevated liver enzymes and, in rare cases, clinical hepatitis
• RUCAM (Roussel Uclaf Causality Assessment Method) analysis of these cases found:
  • No probable relationship between Petadolex and serious liver injury
  • Two cases of non-serious, reversible liver enzyme elevations rated as “probably related”
• In preclinical studies, bile duct hyperplasia was observed only at supratherapeutic doses (45-90 fold the maximum clinical dose)
• Liver function tests in primary human hepatocytes showed no hepatotoxicity at therapeutic concentrations

Regulatory Actions

The Debate

• Proponents argue: The PA-free Petadolex product is safe; the liver injury reports involved other butterbur products that may have contained PAs; RUCAM analysis found no probable causation; ~4 decades of clinical use support safety
• Critics argue: Even PA-free products may cause liver injury through unknown mechanisms; the regulatory precautionary principle justifies withdrawal; reporting of liver injury was likely incomplete
• Diener et al. (2018) published a detailed safety review concluding that the safety profile of Petadolex is acceptable, with emphasis on the liver: no clinically relevant hepatotoxicity was demonstrated in clinical trials, preclinical studies, or independent causality assessments

European vs. US/Anglophone Consensus

The irony: Butterbur was developed in Germany, had the strongest clinical evidence of any herbal migraine treatment, was approved in Germany first, and was then withdrawn from Germany — while remaining available in the US market as a supplement.

Safety Profile

Contraindications

• Liver disease: Do not use in patients with pre-existing hepatic impairment
• Pregnancy and lactation: Contraindicated (insufficient safety data; PA concerns)
• Children: Insufficient data; not recommended in children under 12
• Allergy to Asteraceae (Compositae): Cross-reactivity possible

Drug Interactions

• No well-documented pharmacokinetic interactions
• Theoretical: CYP3A4 substrates (petasin may be metabolized by CYP3A4)
• Caution with other hepatotoxic drugs

Side Effects

• Common: Burping/eructation (most frequently reported; related to the softgel formulation)
• Uncommon: Mild GI symptoms (nausea, flatulence, diarrhea)
• Rare: Headache, fatigue, itchy eyes
• Very rare: Elevated liver enzymes (disputed causality); clinical hepatitis (case reports)

Pregnancy/Lactation

• Contraindicated due to insufficient safety data and residual PA concerns
• No human pregnancy data available

Critical Safety Guidance

• ONLY use products certified PA-free (below detection limit of <0.1 ppm)
• Monitor liver function if using long-term (baseline LFTs, repeat at 4-8 weeks)
• Products that are not specifically manufactured to remove PAs should NEVER be used
• Raw butterbur plant or homemade preparations are DANGEROUS

Clinical Dosage

Migraine Prophylaxis (Petadolex Protocol)

• Effective dose: 75 mg twice daily (150 mg/day total) — based on Lipton et al. (2004)
• Lower dose: 50 mg twice daily (100 mg/day) — less effective but still superior to placebo
• Formulation: Soft gelatin capsules of CO2 extract, standardized to min. 15% petasins
• Duration: Minimum 3-4 months to assess efficacy (migraine prophylaxis trials were 3-4 months)
• Onset: Improvement typically begins within 4 weeks

Allergic Rhinitis (ZE 339 Protocol)

• ZE 339 extract: Standardized for petasins
• 1 tablet 4 times daily (studies)
• Used during allergy season

Key Products

• Petadolex (Weber & Weber): The original PA-free CO2 extract; withdrawn in Germany but available elsewhere
• ZE 339 (Zeller AG): Butterbur extract for allergic rhinitis (Switzerland)
• Tesalin: Butterbur product for allergy

Sources

• Lipton et al. (2004) “Petasites hybridus root (butterbur) is an effective preventive treatment for migraine” Neurology 63(12):2240-4. PMID: 15623680
• Grossman & Schmidramsl (2000) “An extract of Petasites hybridus is effective in the prophylaxis of migraine” PMID: 11410074
• Diener et al. (2018) “Safety profile of a special butterbur extract from Petasites hybridus in migraine prevention with emphasis on the liver” Cephalalgia Reports 1:1-8
• Danesch & Rittinghausen (2003) “Safety of a patented special butterbur root extract for migraine prevention”
• AAN Evidence-Based Guideline Update (2012): NSAIDs and Other Complementary Treatments for Episodic Migraine Prevention
• Agosti et al. (2006) “Hepatobiliary Events in Migraine Therapy with Herbs — The Case of Petadolex” JCM 8(5):652
• Schapowal (2002) Butterbur vs cetirizine for allergic rhinitis, BMJ
• BfArM (German Federal Institute for Drugs and Medical Devices): Market withdrawal notice (2009)
• PMC9108977: “Petasites for Migraine Prevention: New Data on Mode of Action, Pharmacology and Safety” (2022)
• StatPearls (NCBI): Butterbur

Connections

• Stinging Nettle Herb: Alternative herbal approach to allergic rhinitis
• Ginger: Both address headache-adjacent conditions; ginger sometimes used acutely for migraine
• CGRP pathway: Butterbur’s CGRP-blocking mechanism connects it to the newest class of prescription migraine drugs (erenumab, fremanezumab, galcanezumab)
• Pyrrolizidine alkaloid safety: Relevant to other PA-containing herbs (comfrey, coltsfoot, etc.)
• Neuropsychiatric herbs module: Migraine prophylaxis overlaps with neurology-focused herbs