Butterbur

Petasites hybridus · Petadolex · Ze 339

Snapshot

Indications	Contraindications
Migraine prophylaxis¹ Allergic rhinitis² Seasonal allergic rhinitis³ Asthma (open-label data)⁴	Liver disease or dysfunction⁵ Butterbur hypersensitivity⁵ Ragweed-family plant allergy⁶ Products containing alkaloids⁶

Butterbur (Petasites hybridus) is a shrub whose root and leaf extracts are marketed as dietary supplements⁶. Its petasin constituents are thought to act through calcium channel blockade and inhibition of leukotriene and histamine activity⁵. Root extract is used for migraine prevention and leaf extract for allergic rhinitis, and asthma is a third use with open-label data only.

Root extract reduced migraine attack frequency against placebo in randomized trials, with a systematic review rating the evidence limited but positive^{1, 7–9}. Leaf extract was comparable to cetirizine and fexofenadine in allergic rhinitis, though most large trials were manufacturer-funded. A 2022 narrative review of complementary allergy therapies placed butterbur among those with the strongest evidence for allergic rhinitis¹⁰. Products are mainly root or leaf extracts in capsules or softgels; see Form comparison.

The most consequential caution is hepatic: the plant contains pyrrolizidine alkaloids, and LiverTox rates butterbur as a probable cause of clinically apparent liver injury, possibly from contaminants, including cases reported with products labeled pyrrolizidine alkaloid-free¹¹. Per the National Center for Complementary and Integrative Health, only products processed to remove these alkaloids and labeled pyrrolizidine alkaloid-free are considered, and patients are advised to talk with their health care provider before combining butterbur with medicines⁶.

Last updated October 16, 2026. Read how we make monographs.

In the full monograph

47 sources, 38 studies

When to useThe situations practitioners use it for, each with the reason and the study behind it.
SafetyWho should avoid it, who needs extra care, and the side effects reported in studies.
Protocol notesThe doses used in studies, how and when they were taken, and how the forms on the market compare.
How it worksWhat it is and how it works in the body, in plain terms.
Published studiesThe studies behind each use, popular claims checked against them, and trials still under way.
Word of mouthWhat patients and practitioners report online, kept separate from the clinical evidence.
Clinical perspectiveA closing read of where the evidence is solid, where it is thin, and what has not been studied.

Snapshot

In the full monograph

Sources