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.
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.
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.
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.
What is the typical dose of Butterbur?
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.
Is Butterbur safe? Any cautions or side effects?
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.
How many studies support Butterbur?
NutriDex cites 8 sources for Butterbur, graded "Moderate".
Cite this page
APA
Peh, D. (2026). Butterbur (Petasites hybridus): Benefits, Dosage, Side Effects & Evidence. NutriDex — The Supplement Research Compendium. Retrieved 16 Sept 2026, from https://nutridex.info/s/butterbur
BibTeX
@misc{nutridex_butterbur,
author = {Peh, Daryl},
title = {Butterbur (Petasites hybridus): Benefits, Dosage, Side Effects \& Evidence},
year = {2026},
howpublished = {NutriDex --- The Supplement Research Compendium},
url = {https://nutridex.info/s/butterbur},
note = {Reviewed by Dr Daryl Peh, MBBS Singapore, MMed FM. Accessed 2026-09-16}
}
For medical claims, citing the underlying primary studies linked above is preferred. NutriDex is an educational reference, not medical advice.