Supplement analysis backed by scientific evidence · PT

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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.

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  • Guideline status was withdrawn on safety, not efficacy Moderate evidence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with PA-free products, more than 40 cases of liver injury including liver failure have been reported; products were withdrawn in Germany and the UK and sales are restricted in several European countries.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.

Scientific references

Where to buy

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