Butterbur Extract

📜 Historical Use

Butterbur is Petasites hybridus, a shrub that grows in Europe and parts of Asia and North America. Its common name records a piece of practical history rather than a medical one: NCCIH notes that the plant has very large leaves, that those leaves were historically used to wrap butter, and that they also served as protection from rain. The medicinal record NCCIH reports is thin and old. During the Middle Ages, butterbur root was burned in an effort to combat the plague. Between that and the present there is no continuity worth claiming, and the discontinuity is the instructive part. The uses that sell butterbur today, migraine prevention and hay fever relief, are modern ones; NCCIH describes it as marketed as a dietary supplement for migraines, allergic rhinitis and other conditions. The modern product is also chemically unlike anything a medieval user handled, because it is a fraction processed to strip out the pyrrolizidine alkaloids the raw plant contains. The most recent chapter of this history is institutional rather than folk: an endorsement for migraine prevention from the American Academy of Neurology in 2012, withdrawn again in 2015 on safety grounds.

📊 What the Research Shows

NCCIH says that several studies of butterbur for migraine and allergic rhinitis have been done in people, so there is some knowledge of its effects on those two conditions and effectively none on anything else: little research has been done on butterbur for other conditions, and no conclusions can be reached about them. For migraine, NCCIH states that a butterbur root extract may reduce the frequency of migraines in adults and children when taken orally. For hay fever it states that a butterbur leaf extract may be helpful for symptoms of allergic rhinitis when taken orally. The root and leaf distinction is not decorative; it is the difference between the two evidence bases, and product labels do not always make clear which part a capsule contains. The most important fact on this page is what happened next. The American Academy of Neurology endorsed butterbur for migraine prevention in 2012 and then withdrew that recommendation in 2015, and NCCIH attributes the withdrawal to safety concerns rather than to a reversal on efficacy. MSKCC records a similar efficacy picture with an added qualification: butterbur performed comparably to standard antihistamines for allergic rhinitis, but conflicting data show no superiority over placebo for intermittent rhinitis, and the asthma studies are limited enough that a systematic review called for more rigorous investigation before recommending it.

Take 75mg PA-free butterbur extract 2x daily during allergy season.

MUST be PA-free (pyrrolizidine alkaloids are toxic). Don't use raw plant.

⚠️ What happens if taken in excess:

Butterbur carries a liver signal serious enough that it governs everything else on this page. The plant contains pyrrolizidine alkaloids, and NCCIH states that these can damage the liver and the lungs and may cause cancer. Only butterbur products that have been processed to remove the alkaloids and are labelled or certified as PA-free should be considered for use at all. Even then the reassurance is bounded twice over. NCCIH reports that several studies, including studies of children and adolescents, found that PA-free butterbur products seem to be safe when taken by mouth for up to 16 weeks - a duration worth quoting precisely, because nothing read for this page establishes safety beyond it. And NCCIH records rare cases of liver injury associated with products that were reported to be PA-free, which means the PA-free label reduces the hazard without eliminating it. MSKCC states the contraindication plainly: do not take butterbur if you have liver disease or dysfunction, because some compounds present in it can be damaging to the liver, and do not take it if you are hypersensitive to butterbur. Reported side effects are belching, diarrhea, drowsiness, rash and stomach upset. Butterbur may also cause an allergic reaction in people who are allergic to related plants, specifically ragweed, chrysanthemums, marigolds and daisies. Products containing pyrrolizidine alkaloids should not be used during pregnancy or while breastfeeding because they may cause birth defects or liver damage, and little is known about whether PA-free products are safe then.

No source read for this page names a single drug that interacts with butterbur. The NCCIH fact sheet names no medication anywhere, and the MSKCC monograph has no herb-drug interactions section at all. That silence is reported here rather than papered over, and it should be read as an absence of study rather than as a clean record, because an interaction nobody has looked for has not been ruled out. Two concrete things can still be said. The first is a contraindication rather than an interaction, and it is the one that matters: MSKCC says butterbur should not be taken by anyone with liver disease or dysfunction, because some of its compounds can damage the liver. Anyone already taking a drug that burdens the liver falls inside the population that contraindication is about, and that is a conversation to have with a prescriber before starting rather than after. The second is that the pharmacological targets MSKCC names are not obscure ones. Petasin acts on leukotriene and histamine activity, on cyclooxygenase-2 and prostaglandin E2, and as an antagonist at L-type voltage-dependent calcium channels in vascular smooth muscle. Those are the targets of leukotriene modifiers, antihistamines, NSAIDs and calcium channel blockers respectively, but no source read here reports a study of butterbur given alongside any of them, so this page names the overlap and stops there.

1. Butterbur — National Center for Complementary and Integrative Health (NCCIH), National Institutes of Health NCCIH Herbs at a Glance (2024)[NIH ↗]
2. Butterbur — Memorial Sloan Kettering Cancer Center, Integrative Medicine MSKCC About Herbs (2023)[mskcc ↗]