European herb with strong evidence for migraine prevention and allergic rhinitis. Critical safety requirement: ONLY use PA-free standardized extracts (Petadolex, Ze 339). Raw herb is hepatotoxic.
Traditions: European herbalism
Used in Middle Ages for plague and fever. By the 17th century, used for cough, asthma, and skin wounds. German Commission E approved the root for urinary tract spasms. Modern use focuses on migraine prevention - not a traditional indication but emerged from clinical research in the 1990s-2000s.
Strong evidence for migraine prophylaxis and allergic rhinitis using PA-free standardized extracts. Migraine: 48% reduction in attack frequency with 75mg BID in 245-patient trial. Allergic rhinitis: comparable efficacy to cetirizine without sedation. Mechanism includes CGRP antagonism (same pathway as modern migraine drugs) and inflammatory mediator suppression. Critical: 33% of commercial products contained hepatotoxic PAs in one review. Only use verified PA-free products.
245 patients, 4 months: 75mg BID produced 48% reduction in attacks vs 26% placebo (p=0.0012). 68% achieved ≥50% reduction.
125 patients: Ze 339 extract showed comparable efficacy to cetirizine, with fewer sedative effects.
CRITICAL: Only PA-free CO₂ extracts (Petadolex for migraine, Ze 339 for allergic rhinitis). Standardized to petasin content. Never use crude herb, teas, or tinctures - they contain hepatotoxic pyrrolizidine alkaloids (PAs).
Butterbur has strong clinical evidence for two specific conditions - when using the right products:
Migraine prophylaxis: In a 245-patient trial over 4 months, 75mg twice daily reduced migraine frequency by 48% compared to 26% with placebo [1]. You’re likely to see results - 68% of people achieved at least a 50% reduction in attacks [1]. A smaller 60-patient trial found a 60% reduction compared to baseline [2]. The effect builds over months, not days.
Allergic rhinitis: In 125 people with hay fever, butterbur extract worked as well as cetirizine (Zyrtec) but without the drowsiness [3]. In a postmarketing study of 580 people, 90% reported symptom improvement after 2 weeks [4]. You may notice less congestion and sneezing within 5-7 days [5]. The extract reduces specific inflammatory markers - histamine dropped 65%, leukotrienes dropped 42-49% in one trial [5].
How it works: Butterbur blocks CGRP (calcitonin gene-related peptide) signaling - the same pathway targeted by modern migraine medications like Aimovig and Emgality [6]. It also dampens pain signals through TRP ion channels and suppresses multiple inflammatory mediators [5,6].
The evidence is specific to standardized extracts - Petadolex (root extract) for migraine, Ze 339 (leaf extract) for allergic rhinitis. These are CO₂ extracts standardized to petasin content and verified PA-free.
Butterbur is native to Europe and has the largest leaves of any indigenous European plant - up to 3 feet across. The name likely comes from using these large leaves to wrap butter.
In the Middle Ages, Europeans used it for plague and fever. By the 17th century, the documented uses shifted to cough, asthma, and treating skin wounds. The German Commission E (Germany’s regulatory body for herbal medicine) approved the root for urinary tract spasms, especially with kidney stones.
Interestingly, migraine prevention - now the most evidence-based use - is NOT a traditional indication. This emerged from clinical research in the 1990s-2000s when researchers investigated the plant’s anti-spasmodic and anti-inflammatory properties.
Traditional European preparations included teas, poultices, and various crude herb preparations. Modern understanding of pyrrolizidine alkaloid toxicity has made these traditional preparations obsolete and unsafe - historical practitioners were unaware these compounds caused liver damage.
For migraine prevention:
Start with Petadolex or equivalent PA-free root extract standardized to at least 7.5mg petasins per dose. Take 75mg twice daily (morning and evening) with food. The 150mg/day dose has the strongest evidence - a lower 100mg/day dose showed only 36% reduction and wasn’t statistically better than placebo [1,7].
Plan for a 4-month trial. This isn’t a quick fix. Some people notice fewer migraines after 1-2 months, but the full effect builds over 12-16 weeks. Track your migraine frequency in a diary - you’re looking for at least a 50% reduction in attacks, and using less acute medication (triptans, NSAIDs).
For allergic rhinitis:
Use Ze 339 or equivalent PA-free leaf extract standardized to 8mg petasines per tablet. Take 1 tablet 3-4 times daily during allergy season. You may notice improvement within 5-7 days - less runny nose, congestion, and sneezing [5].
Start at the beginning of your allergy season or when symptoms begin. Some people use 3-4 tablets daily for severe symptoms, then drop to 1-2 tablets as maintenance once symptoms improve. Duration is typically 2 weeks but can continue throughout the season.
For migraine:
For allergic rhinitis:
Safety monitoring: Get baseline liver function tests (AST, ALT, ALP, bilirubin) before starting. Repeat at 4-6 weeks and 3 months. Stop immediately and contact your doctor if you notice yellowing skin or eyes, dark urine, light-colored stools, or severe fatigue - these are liver warning signs.
Consider butterbur if:
Avoid butterbur if:
This is THE most important section for butterbur. Product quality determines both safety and efficacy.
The pyrrolizidine alkaloid (PA) problem: Raw butterbur contains compounds called pyrrolizidine alkaloids that damage the liver. The WHO database has 40 cases of liver toxicity from butterbur, including 2 people who needed liver transplants [8]. In one review, 7 of 21 commercial butterbur products (33%) contained PAs - including some claiming to be “PA-free” [8].
PA-free products are safe: Petadolex, the most studied extract, has 2.3 million patient-months of use with ZERO cases of liver damage in the USA and Canada [8]. When products are properly made with CO₂ extraction and verified PA-free, they have excellent safety - the main side effect is mild burping (3.8-7.4% in trials) [1,4,9].
What to verify before buying:
Red flags - do not use:
The American Academy of Neurology stopped recommending butterbur in 2015 due to liver toxicity concerns [10] - this decision was made during a period when PA contamination was a major issue. The evidence shows PA-free products are safe, but the contamination problem is real. Only use products where you can verify PA-free status with documentation.
Butterbur has strong evidence for migraine prevention and seasonal allergies, with clear mechanisms of action validated by modern research. A 4-month trial with 75mg twice daily may cut your migraines in half. For hay fever, taking 24-32mg petasines daily may work as well as antihistamines without the drowsiness.
But quality is non-negotiable. This isn’t a situation where “any butterbur will do” - 33% of products failed safety testing in one review. Only use pharmaceutical-grade, CO₂-extracted, PA-free products (Petadolex for migraine, Ze 339 for allergies) with verified certificates of analysis. Never use crude herb, teas, or tinctures. Get baseline liver tests and monitor during treatment.
When used properly with verified products, butterbur is a well-studied botanical with clinical trial evidence comparable to many pharmaceuticals. When used improperly with contaminated or crude products, it can cause liver failure. The difference is in the extraction method and quality verification - not the plant itself.
Duration: Migraine: 4 months minimum - effects build over time. Allergic rhinitis: 2 weeks typical, improvements often visible by 5-7 days.
What to notice:
**Timing**: Migraine - take morning and evening with food. Allergic rhinitis - spread throughout day (3-4 times). **Monitoring**: Get baseline liver tests before starting, repeat at 4-6 weeks and 3 months. **Duration limits**: Evidence supports safety up to 16 weeks. Longer-term use not well-studied. **Quality matters**: 33% of commercial products contained PAs in one review - verify PA-free status with certificate of analysis.
Generally considered: caution
Contraindications:
**The PA problem**: Raw butterbur contains pyrrolizidine alkaloids (PAs) that cause liver damage. WHO database has 40 cases of hepatotoxicity, 2 liver transplants - likely from contaminated products. 7 of 21 commercial products (33%) contained PAs in one review. **PA-free products have excellent safety**: Petadolex had 2.3 million patient-months of use with ZERO liver damage cases in USA/Canada. **Common side effects**: 3.8-7.4% get mild GI issues (burping). Two cases of reversible liver enzyme elevations with Petadolex (non-serious). **Red flags**: Any product claiming to be 'natural' or 'traditional' without PA-free certification and third-party testing should not be used.