Butterbur (Petasites hybridus, Ze 339)
Standardised Ze 339 extract has American Academy of Neurology Level A evidence for migraine prevention; only PA-free preparations are safe.
Why
Butterbur (Petasites hybridus) rhizome extract has unusual evidence for a herbal product: the standardised PA-free extract Ze 339 (Petadolex) received a Level A recommendation for migraine prevention from the American Academy of Neurology in 2012. A separate body of RCTs supports the same extract for allergic rhinitis, with effects comparable to fexofenadine. The AAN later withdrew the Level A rating in 2015 over hepatotoxicity concerns: not because the efficacy evidence weakened, but because preparations on the market vary in pyrrolizidine alkaloid (PA) content.
How it works
Petasin and isopetasin inhibit leukotriene synthesis and reduce calcium influx in vascular smooth muscle, dampening the neurovascular inflammation implicated in migraine. The same mechanism reduces nasal mucosal swelling and rhinorrhoea in allergic rhinitis.
Expected onset · Migraine prevention: effect emerges over 8–12 weeks. Allergic rhinitis: 1–2 weeks.
How to take
Dosage
Ze 339 / Petadolex: 75 mg twice daily for migraine prevention. Allergic rhinitis: 50 mg three times daily.
Timing
Twice or three times daily with food
On the label
'PA-free' (or 'pyrrolizidine alkaloid-free') standardised extract: Petadolex, Ze 339, or Petaforce. Generic butterbur is potentially hepatotoxic and should not be used.
Ideal for
Adults with episodic migraine; adults with seasonal allergic rhinitis when first-line antihistamines are not tolerated.
Safety
Evidence
Lipton 2004 Neurology RCT (n=245): Petadolex 75 mg twice daily reduced migraine frequency by 48% vs 26% on placebo over 16 weeks. AAN/AHS 2012 guideline rated butterbur Level A for migraine prevention, later withdrawn in 2015 over hepatotoxicity concerns with non-PA-free products, not the efficacy data. Schapowal 2002 BMJ RCT: Ze 339 non-inferior to cetirizine for seasonal allergic rhinitis.
- Lipton et al., Neurology 2004, Petasites hybridus root (Petadolex) for migraine prevention (RCT, n=245)
- Holland et al., Neurology 2012, AAN/AHS evidence-based guideline update: pharmacologic treatment for episodic migraine prevention
- Schapowal, BMJ 2002, butterbur Ze 339 vs cetirizine for seasonal allergic rhinitis (RCT)
Where to get it
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