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Moderate evidenceBrain & cognition

Butterbur

Butterbur root extract at 75 mg twice daily cut migraine frequency by 48% versus 26% for placebo in a well-designed 245-patient trial, making it one of the better-evidenced herbal preventives. The problem is safety: unpurified butterbur is hepatotoxic, and the American Academy of Neurology withdrew its recommendation over liver injury reports.

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What the science says

  • Migraine prevention Moderate evidence

    In a three-arm randomised trial of 245 migraine patients, Petasites extract 75 mg twice daily reduced attack frequency by 48% over 4 months versus 26% on placebo (p = 0.0012), with 68% versus 49% of patients achieving a 50% or greater reduction. The 50 mg twice-daily arm did not separate from placebo, so dose matters.

  • Guideline status was withdrawn on safety, not efficacy Moderate evidence

    The 2012 AAN and American Headache Society guideline update graded butterbur Level A (established efficacy) for episodic migraine prevention. The AAN subsequently retired that recommendation because of hepatotoxicity concerns — the efficacy data were never refuted, but the risk-benefit calculation changed.

  • Allergic rhinitis Limited evidence

    Several small trials suggest butterbur extract relieves nasal symptoms comparably to cetirizine or fexofenadine without sedation, but the studies are small, short and largely funded by a single manufacturer.

Dosage & safety

Studied dose50-75 mg twice daily of a standardised, certified pyrrolizidine-alkaloid-free root extract (petasin/isopetasin standardised, the Petadolex-type preparation). 75 mg twice daily is the dose with proven efficacy. Preventive trials ran 3-4 months.
SafetySafety dominates this entry. Raw butterbur contains pyrrolizidine alkaloids that are hepatotoxic and carcinogenic — only certified PA-free extracts should ever be used. Even with PA-free products, more than 40 cases of liver injury including liver failure have been reported; products were withdrawn in Germany and the UK and sales are restricted in several European countries. Do not use in liver disease, pregnancy, breastfeeding or children. Cross-reactive allergy is possible in people sensitive to ragweed, marigolds, daisies and chrysanthemums (Asteraceae family). The commonest mild side effect is burping. If used at all, use only a certified PA-free product under medical supervision with periodic liver enzyme monitoring.

How to take it

TimingTwice daily; timing within the day does not matter, and preventive trials ran 3-4 months.
With food?With food, which reduces the burping that is the commonest complaint.
Worth knowingOnly a certified pyrrolizidine-alkaloid-free extract is ever acceptable, and even then get baseline liver enzymes before starting and periodic checks after.

Interactions

With medications

  • hepatotoxic drugs (methotrexate, isoniazid, some antifungals, high-dose paracetamol)

    Over 40 cases of liver injury including liver failure have been reported with butterbur, so the risks compound. do not combine; have liver enzymes monitored if you use it at all

With other supplements

  • kava, green tea extract, black cohosh and other liver-stressing botanicals

    Additive risk of drug-induced liver injury. do not stack hepatotoxic botanicals

Well-established interactions only — this is not a complete list. Always tell your doctor and pharmacist what you take.

Frequently asked questions

Does butterbur prevent migraines?

Butterbur has moderate evidence: in a trial of 245 patients, 75 mg twice daily cut migraine frequency by 48% versus 26% on placebo. The 50 mg twice-daily dose did not beat placebo.

Is butterbur safe for the liver?

Butterbur carries a real liver risk: raw butterbur contains hepatotoxic pyrrolizidine alkaloids, and even with PA-free products more than 40 cases of liver injury, including liver failure, have been reported. Use only a certified PA-free extract, under medical supervision with liver enzyme monitoring.

Why was butterbur removed from migraine guidelines?

The AAN graded butterbur as established for migraine prevention in 2012, then retired the recommendation because of liver toxicity concerns. The efficacy data were never refuted — the risk-benefit balance changed.

Who should not take butterbur?

Do not use butterbur in liver disease, pregnancy, breastfeeding or children, or alongside other liver-stressing drugs or botanicals such as kava or black cohosh. People allergic to ragweed, marigolds or daisies may also react to butterbur.

Scientific references

Where to buy

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