Butterbur (Petasites hybridus): Benefits, Dosage, Side Effects & Evidence

Q: What is Butterbur used for?

Butterbur is most often taken for Fewer migraine attacks, Hay-fever / allergic rhinitis relief, Non-sedating antihistamine alternative. A migraine and hay-fever herb shadowed by liver-toxicity concerns.

Q: Does Butterbur work — what does the evidence say?

Moderate evidence. Several controlled trials; effects real but modest or context-dependent. Butterbur is a perennial shrub whose root and leaf extracts are used for migraine prevention and allergic rhinitis. In randomized trials, a standardized root extract (Petadolex) at 75 mg twice daily cut migraine frequency by 48% versus 26% on placebo over four months, with 68% of patients achieving a >=50% reduction. For seasonal allergies, leaf extract (Ze 339) matched cetirizine and fexofenadine for symptom relief without the antihistamine sedation. The catch is safety: raw butterbur contains pyrrolizidine alkaloids that are hepatotoxic and potentially carcinogenic, and roughly a third of commercial products tested still contained them. Cases of cholestatic hepatitis, including two requiring liver transplant, prompted the AAN to withdraw its 2012 recommendation in 2015. Only certified PA-free, standardized extracts should be used, and even those warrant caution and periodic liver monitoring.

Q: How many studies support Butterbur?

NutriDex cites 8 sources for Butterbur, graded "Moderate".

Peh, Daryl

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Butterbur

Petasites hybridus

A migraine and hay-fever herb shadowed by liver-toxicity concerns.

Moderate evidence 🛡️Gut & Immune

✚ Updated 7 Jun 2026 · How we grade evidence

Evidence tier

Moderate

Research weight

Citations

8 verified / 8

Classification

Gut & Immune

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What the evidence says. Graded moderate: several good RCTs show real reductions in migraine frequency and hay-fever symptoms (comparable to antihistamines), but the American Academy of Neurology retracted its endorsement in 2015 over pyrrolizidine-alkaloid liver toxicity, and product quality varies widely. (Moderate evidence: Several controlled trials; effects real but modest or context-dependent.)

What is Butterbur?

Butterbur (Petasites hybridus) is a gut and immune supplement used for fewer migraine attacks. NutriDex grades the human evidence as Moderate. Butterbur is a perennial shrub whose root and leaf extracts are used for migraine prevention and allergic rhinitis. In randomized trials, a standardized root extract (Petadolex) at 75 mg twice daily cut migraine frequency by 48% versus 26% on placebo over four months, with 68% of patients achieving a >=50% reduction. For seasonal allergies, leaf extract (Ze 339) matched cetirizine and fexofenadine for symptom relief without the antihistamine sedation. The catch is safety: raw butterbur contains pyrrolizidine alkaloids that are hepatotoxic and potentially carcinogenic, and roughly a third of commercial products tested still contained them. Cases of cholestatic hepatitis, including two requiring liver transplant, prompted the AAN to withdraw its 2012 recommendation in 2015. Only certified PA-free, standardized extracts should be used, and even those warrant caution and periodic liver monitoring.

Purported Benefits

✓Fewer migraine attacks

✓Hay-fever / allergic rhinitis relief

✓Non-sedating antihistamine alternative

Evidence by outcome

The same supplement can be well-proven for one use and unproven for another — here is the human evidence graded outcome by outcome.

Outcome	Evidence	Effect	Studies
Migraine prevention (frequency)Standardized root extract cut attack frequency ~48% vs 26% placebo; AAN Level A later retracted over hepatotoxicity, not efficacy.	Moderate	↑ benefit · moderate	3
Allergic rhinitis / hay-fever reliefLeaf extract Ze 339 matched cetirizine and fexofenadine in RCTs; consistent symptom benefit.	Moderate	↑ benefit · moderate	3
Non-sedating vs antihistaminesComparable efficacy to cetirizine/fexofenadine without the sedation reported by antihistamine users.	Moderate	↑ benefit · moderate	2

Dosing & Compounds

Typical Dose

For migraine, 50–75 mg of a PA-free root extract (e.g. Petadolex) twice daily; for allergic rhinitis, a standardized leaf extract (Ze 339) one tablet 3–4x daily. Use only certified PA-free products.

Active Compounds

PetasinIsopetasinSesquiterpene esters

Safety & Cautions

Raw butterbur contains pyrrolizidine alkaloids (PAs) that are hepatotoxic and potentially carcinogenic; only certified PA-free, standardized extracts should ever be used, and even these have been linked to cases of cholestatic hepatitis (two requiring liver transplant). Avoid in pregnancy, breastfeeding, and liver disease, and stop immediately for jaundice, nausea, dark urine, or abdominal pain. Being a ragweed-family (Asteraceae) plant, it can trigger allergy in sensitive people, and it may add to the effects of liver-stressing drugs; periodic liver-function monitoring is prudent. Educational only — always check with your doctor or pharmacist before combining Butterbur with any medicine.

Key Studies

Systematic review Braunwalder et al. 2025 ✓ PubMed

A systematic review of 14 clinical studies in seasonal allergic rhinitis identified Petasites hybridus (butterbur) as the most-studied herb, with consistent beneficial effects on immunological parameters, subjective nasal symptoms, and nasal airflow (qualitative synthesis; no pooled effect size).

Systematic review Agosti 2006 ✓ PubMed

Systematic review of 2 RCTs (293 patients) found moderate evidence for the higher 150 mg/day dose of Petadolex in migraine prophylaxis.

RCT Lipton 2004 ✓ PubMed

Petadolex 75 mg bid cut migraine frequency 48% vs 26% placebo over 4 months (p=0.0012); 68% achieved >=50% reduction (n=245).

RCT Grossmann 2000 ✓ PubMed

Petasites root extract 50 mg bid for 12 weeks reduced migraine attack frequency up to 60% vs baseline, significant over placebo (n=60).

RCT Schapowal 2002 ✓ PubMed

Butterbur (Ze 339) was as effective as cetirizine for seasonal allergic rhinitis but without the sedation reported by two-thirds of cetirizine patients (n=125).

RCT Schapowal 2005 ✓ PubMed

Butterbur Ze 339 (one tablet 3x daily) was comparably efficacious to fexofenadine and superior to placebo for intermittent allergic rhinitis (n=330).

Safety LiverTox 2018 ✓ Full text

Likelihood score C; 10 cases of cholestatic hepatitis linked to butterbur, 2 needing liver transplant; PA-free extracts not implicated.

Review Holland 2012 (AAN/AHS) ✓ Source

Evidence-based guideline rated Petasites Level A for episodic migraine prevention; recommendation later retracted in 2015 over hepatotoxicity concerns.

NutriDex

Butterbur

What is Butterbur?

Purported Benefits

Evidence by outcome

Dosing & Compounds

Safety & Cautions

Key Studies

Common questions about Butterbur

What is Butterbur used for?

Does Butterbur work — what does the evidence say?

What is the typical dose of Butterbur?

Is Butterbur safe? Any cautions or side effects?

How many studies support Butterbur?