Butterbur: Evidence, Trial Doses & Interactions

About Butterbur

A rhizome extract standardised to the sesquiterpenes petasin and isopetasin, used for migraine and allergic rhinitis. Raw butterbur contains pyrrolizidine alkaloids and must be processed to remove them.

Butterbur has the strongest migraine trial data of any botanical here — and its main branded extract was withdrawn from several markets after liver injury reports, some of them serious. Regulators in Germany and the UK acted on hepatotoxicity signals that appeared even with alkaloid-free preparations, so the safety question is not simply about pyrrolizidine alkaloids. Unprocessed butterbur is unequivocally hazardous.

Sold as

PA-free standardised extract, Capsule, Tablet

Standardised to

Trials used extract standardised to 7.5 mg petasins per 50 mg capsule, certified PA-free — a product without this marker may not resemble what was studied.

Also known as

Petasites, Bog rhubarb, Blatterdock

Regulation: Withdrawn or suspended in Germany, the UK and elsewhere following reports of serious liver injury. The UK medicines regulator issued a public advisory against use of unlicensed butterbur products. Any preparation not certified free of pyrrolizidine alkaloids should be considered unsafe.

What the research used

The amounts, forms and durations published trials of Butterbur actually administered.

These are the amounts published trials administered — not a recommendation, and not a dose to copy. Trial participants were screened, supervised and given a characterised preparation. What is in a retail bottle is frequently not what was studied, and the amount that suits one person is not general advice.

Studied for Migraine frequency
100–150 mg
Moderate
PA-free standardised root extract, divided doses · 15% petasins · 3–4 months
The 150 mg per day arm outperformed 100 mg in the pivotal trials, which used one branded extract now withdrawn in several countries over liver injury. That withdrawal is the most important fact about this dose.
Studied for Seasonal allergic rhinitis
32–96 mg
Limited
PA-free leaf or root extract, divided doses · 2 weeks
Trials compared it against antihistamines rather than placebo in several cases, which limits what can be concluded.

This is general information about food, not medical advice. It cannot diagnose, treat or replace guidance from a clinician who knows your history.

When it was taken

Each window says whether a trial compared it against an alternative, or whether it is convention and pharmacology. Most timing advice is the second kind.

None of the timings below were directly compared in a trial. They reflect how the research happened to dose, or what the pharmacology implies — which is not the same as a timing being better.

Split through the day
Not enough
Trials dosed it two or three times daily to maintain exposure. No timing comparison has been made.
Timing was not directly compared. This reflects convention or how the compound behaves in the body, not a trial showing this window works better.

Cognitive function

Brain & Cognitive Health

Limited evidence

Randomised trials report fewer migraine days with a standardised PA-free extract over three to four months. The finding was strong enough for headache guidelines to note it, and subsequently qualified when the extract was withdrawn in several countries over liver injury reports.

What may be going on: Petasins inhibit calcium channels and leukotriene synthesis, which has been linked to effects on cerebral vascular tone.

Limited evidence. Early human work, or mostly lab and animal research.

View the 3 sources

An extract of Petasites hybridus is effective in the prophylaxis of migraine.(opens in a new tab)
Randomised controlled trial · Alternative medicine review : a journal of clinical therapeutic · 2001 · PMID 11410074
Effectiveness of Petasites hybridus preparations in the prophylaxis of migraine: a systematic review.(opens in a new tab)
Systematic review · Phytomedicine : international journal of phytotherapy and phytopharmacology · 2006 · PMID 16987643
Petasites hybridus root (butterbur) is an effective preventive treatment for migraine.(opens in a new tab)
Randomised controlled trial · Neurology · 2004 · PMID 15623680

Deep research mode adds each paper’s own conclusion and stated limitations.

Respiratory function

Respiratory Health

Limited evidence

Some trials report reduced nasal symptoms in seasonal allergic rhinitis, in a few cases similar to an antihistamine. Trials are small, short and several lacked a placebo arm.

Limited evidence. Early human work, or mostly lab and animal research.

View the 2 sources

The butterbur extract petasin has no effect on skin test reactivity induced by different stimuli: a randomized, double-blind crossover study using histamine, codeine, methacholine, and aeroallergen solutions.(opens in a new tab)
Randomised controlled trial · Journal of investigational allergology & clinical immunology · 2006 · PMID 16784008
Treating intermittent allergic rhinitis: a prospective, randomized, placebo and antihistamine-controlled study of Butterbur extract Ze 339.(opens in a new tab)
Randomised controlled trial · Phytotherapy research : PTR · 2005 · PMID 16114089

Deep research mode adds each paper’s own conclusion and stated limitations.

Things to know

Interactions, contraindications and dose limits, most serious first. Concentrated extracts interact with medication in ways the whole plant does not, so this section carries more weight here than it does on a food page.

Worth knowing
Pyrrolizidine alkaloids cause hepatic veno-occlusive disease
Raw butterbur contains pyrrolizidine alkaloids, the same class found in comfrey, coltsfoot and borage, which cause hepatic veno-occlusive disease — irreversible blockage of small liver veins — and are carcinogenic in animals. Only preparations certified free of these alkaloids should ever be considered.
Worth knowing
Liver injury reported even with PA-free extracts
Serious hepatitis cases were reported with a certified alkaloid-free branded extract, prompting withdrawal in Germany and a regulatory advisory in the UK. Liver monitoring was recommended for anyone continuing it.
Avoid
Pregnancy, breastfeeding and children
Pyrrolizidine alkaloid exposure is especially dangerous to a developing liver. Butterbur should not be used in pregnancy, while breastfeeding, or by young children.
Allergy
Asteraceae allergy
Butterbur is a daisy-family plant, so people allergic to ragweed, marigold, chrysanthemum or chamomile may react.
Interaction
Other liver-affecting drugs
Interacts withHepatotoxic drugs, alcohol
Combining butterbur with medications that carry their own hepatotoxicity risk compounds an already documented problem.

Butterbur

What butterbur may help with

About Butterbur

What the research used

When it was taken

Split through the day

The evidence in depth

Cognitive function

Respiratory function

Things to know

Pyrrolizidine alkaloids cause hepatic veno-occlusive disease

Liver injury reported even with PA-free extracts

Pregnancy, breastfeeding and children

Asteraceae allergy

Other liver-affecting drugs

What butterbur may help with

About Butterbur

What the research used

When it was taken

🔀Split through the day

The evidence in depth

Cognitive function

Respiratory function

Things to know

Pyrrolizidine alkaloids cause hepatic veno-occlusive disease

Liver injury reported even with PA-free extracts

Pregnancy, breastfeeding and children

Asteraceae allergy

Other liver-affecting drugs

Split through the day